Hello everyone,
I am very new to solar/wind and trying to plan a proper system for my own needs. This is for a total off-grid system to run a small house, but filled with lots of electricals.
I have been researching this for months on places like YouTube, these forums and other places. I am now familiar with several basics, but have a very long way to go.
My main problem is trying to figure out the best type of setup to meet all my needs, but a solid configuration continues to elude me.
I just purchased a Midnite Solar 6 string combiner and plan to split the load for two controllers. I have CSUN 305 Poly panels (I bought a pallet, so have many, many extras I will not need, but got a nice price buy buying bulk). I have 16 Trojan T105 RE's broken into two banks of 8 wired at 24 volts. I am having a problem finding proper controllers to get, seeing many different ones on places like Amazon, but due to the high watt panels, I can't seem to find a proper controller, nor how many panels would be optimal for my needs.
I also have two 600 watt wind generators (one for each bank), mainly as back-up and for the night breezes to help keep the battery banks charged at all times. On a side note, can I use this MidNite combiner box with the wind generators, coming off from the DC side on the wind controllers to feed the batteries?
I'm located just south of San Diego, CA, so have a really good amount of sun year around and temperatures extremely mild and constant year around, so weather is not a factor here.
My electricals are all new and Energy Star where possible. I run 1 large refrigerator about 25 CF and a smaller refrigerator at 10 CF, then a large stand-up freezer at 23 CF. All new and Energy Star. I will also be running a in-line water pump on the property, along with a Jacuzzi motor for a whirlpool tub. The water heater and stove.oven are propane and no "heater" style appliances used, except for the occasional microwave (1,100 watts) and a toaster. These will be my main draws. I have other electronics, such as flat screen TV's, stereo receivers, etc. but those are not used a lot. I have two laptops which one runs 24/7 and the other used randomly, but typically not more than 8 hours a week.
My goal is finding the optimum configuration for my needs and location.
Thanks in advance for any help and if I missed any details, please feel free to ask.
SouthPacific
Hi SP, welcome to the Forum.
The most successful battery-based power systems begin with a clear knowledge of the LOADs that the system needs to supply, and when these loads will occur.
Will this be an off-grid system, or connected to the Grid?
It seems that you might well be starting in the middle, or the end of a process, and trying to work backward.
Would suggest that you STOP buying any more hardware, and concentrate on your loads, and then do several paper designs to make certain that the system will work on paper, before buying any more neat things.
Batteries need to be charged, even while sitting waiting for the rest of the system to come together ... are you doing this now, and how?
Parallel strings of batteries can often cause trouble, with that number of batteries, you might really want to consider a 48 Volt system.
And, if you will be off-grid, with your three refer units, a 48 V system is probably best. 48 V systems make better use of a Charge Controller's (CC's) output current -- the same output current yields twice the power on 48 V vs a 24 V system.
Here is a Link to another Forum, which has a broad range of topics, and has fairly good participation, as does this site:
http://forum.solar-electric.com/
Just to try to get this started, FWIW, Vic
Hello Vic,
Thank you for the reply.
Yes, you are correct, I have been buying way too much for my use .. but learning a lot. :P
I know I should have done the load test months ago, but just put on the Kill-A-Watt on the line now and will see what 24 hours of regular use gives me. I just want to make sure at special times, I have the juice to throw a party or just play my music for a few hours at a time. And that will consist of a couple of 800 watt receivers with 4-400 watt subs, etc. which I know will be a drain, but again, will be maybe once or twice a month. The majority of the time it will be the basics.
Yes, this will be a total off-grid system. That is why I added the two wind turbines to hopefully catch some juice at night as well. I have read that by keeping the battery banks fully charged as much as possible, they will provide many years of good service if maintained well.
I have done everything I can think of to cut usage, but still have my favorite toys (like the music and Jacuzzi bathtub). I have all LED lighting, most only using 6-8 watts per light and making sure the appliances are as efficient as I could get.
So I will report back in about 24 hours with the watt usage and we can go from there.
Thanks again and hope you are having a wonderful Thanksgiving holiday with family and friends. :)
SouthPacific
Hello SouthPacific,
Regarding the MNPV6 Combiner and the wind turbines, the Combiner, generally would not be used as a connection point for a turbine, in most systems.
If you live in a very windy location, a turbine might be able to contribute some power to your system. There are a number of turbines that have very optimistic specifications on power output. Hope that your turbines are among the ones that have honest specs. Often turbines need to be mounted fairly high off of the ground to get clean air.
AND, as before, how is it that you are charging the batteries that you already have?
Batteries that sit, off of charge, still have a self-discharge, and will Sulfate after a month, or so.
Regarding your PV modules and CCs, the design approach would depend on what will be your system voltage, and some other details.
More later, Vic
You are going to need a backup generator for the times that there is no solar, and you can use the jacuzzi to keep it exercised The pumps & heaters will quickly drain even a large battery bank.
Quote from: Vic on November 26, 2016, 12:15:26 AM
Hello SouthPacific,
Regarding the MNPV6 Combiner and the wind turbines, the Combiner, generally would not be used as a connection point for a turbine, in most systems.
If you live in a very windy location, a turbine might be able to contribute some power to your system. There are a number of turbines that have very optimistic specifications on power output. Hope that your turbines are among the ones that have honest specs. Often turbines need to be mounted fairly high off of the ground to get clean air.
AND, as before, how is it that you are charging the batteries that you already have?
Batteries that sit, off of charge, still have a self-discharge, and will Sulfate after a month, or so.
Regarding your PV modules and CCs, the design approach would depend on what will be your system voltage, and some other details.
More later, Vic
Hi Vic,
Thanks again for the reply. I'll try to make sure I read and answer all questions and my apologies for missing some already.
First, I am very much a beginner here, so most of my lines of thought come from research on YouTube and many other sources, then a bit of general electrical knowledge from regular style house wiring (still not an expert, but have done regular style panels in many homes).
On the wind generators, I got those in an attempt to compensate for electrical power during night time ours to help charge the batteries even at night when we have some wind. So my line of thought (and only thought) was to hook the DC side of the wind controller to the combiner panel to minimize wiring issues. I understand that the "ratings" on these are not going to be very accurate and given it is wind generated will vary greatly.
Luckily, my area of the world is extremely predictable the huge amount of time. I live just south of San Diego CA on the Mexico side of the border (I can see downtown San Diego from here) and I live on a hillside about 1/3 mile away from the waters edge, so the ocean keeps things extremely temperate all year around. Typical winter is high of about 70 and low of about 50 with very few exceptions. Summer, high of 80 and low of 60 with very few exceptions. Lots of sun the huge majority of time (hence the solar) and not a lot of wind, typical breezey days of 7-12 mph, making the wind generator not great, but at least something to possibly compensate over night hours.
I have built good towers for the wind generators. They are up about 40 ft with perfectly clear clean wind when it is blowing
As to the battery banks, I purchased the batteries about 5 months ago and have custom wired them for now at 12 volt banks and keep them charged with the land power and 12 volt chargers. I understand this is important not to let them just sit, so I put a charger on them about once a week to 10 days, which the banks then meter out around 87% and I make sure the banks get fully charged each time to keep them active. I just transferred one bank over to the 24 volt configuration and have begun testing the solar panels and wind generation on that bank. That is why I started researching on the controllers. I have some 12/24 volt 30 amp basic controllers, then tried another "cheap" MPPT 60 amp controller, only to find it was not an real MPPT and a POS. :P Then I found the MidNite solar site and began using the calculator tools and seeing the real stats for the panels I have (they are CSUN 305's) and now trying to find proper controllers to run these panels and the best configuration for my setup.
I did finally get a true base reading on my usage. The Kill-O-Watt meter for 24 hours sits at 7.1 kw for 24 hours. This is an average style day with only the very basics running. When I say basics, it is the usual things that will be running in the 24 hour period. This does NOT include things like the Jacuzzi motor or other extras like stereo receivers, powered subs,etc. But it does include the two refrigerators, freezer, laptops, TV, etc. (typical things used everyday).
To summarize again, I have 16 of the Trojan T105 RE's. I have them custom length cabled with 2/0 wire and proper copper lugs (I got the good crimping tool, knowing I would have to do lots of connections) with most battery to battery connections being the same length with almost all under 1 ft each. Also, I configured distance from solar panels to controller to a minimum, which is 30 feet max and controller to battery bank around 6-8 feet. So I have tried to think of all the best configurations to maximize the efficiency of the entire system. The run from the wind generators to the controllers is less than 100' using 10 gauge wire and 10 gauge wire from controller to batteries in under a 10' run.
My plans were to use 2 banks of 8 batteries in series/parallel combinations using 24 volt settings and inverters. Using one bank to run all the small items and the other for the big items, like the refrigerators. But I am totally open to any and all suggestions/recommendations...that's why I am here..I need expert advise. :)
So based on this information, what would you suggest? Or if you need more information, please let me know in detail and I will answer any questions and provide all the specific information I can.
Thanks again!
SouthPacific
Quote from: mike90045 on November 26, 2016, 02:45:56 AM
You are going to need a backup generator for the times that there is no solar, and you can use the jacuzzi to keep it exercised The pumps & heaters will quickly drain even a large battery bank.
Hello Mike,
Thanks very much for the reply.
Based on my battery bank sizes and configurations, would the Jacuzzi motor run a bank down when used for say 30 minutes? I understand that such things as electric heating elements take huge amounts of usage, so I have tried to stay away from any of those. My stove/oven and water heater are propane. Also, I am learning with the wind generators, I have seen things on YouTube regarding "dump loads" for those. I would like to get your opinion on an idea I had. Instead of getting a dump load resistor, getting a water heating element as the "dump load" drop-off which would activate the heating element and could be used for additional hot water supply??? Is this something that would work?
Again, thanks for the reply and any and all suggestions/recommendations is greatly appreciated. :)
SouthPacific
A wind turbine dump load, must be an ultra-reliable "Must Function" sort of load. It has to be rated to absorb the full hurricane power the wind turbine can output, and when that happens, I'd have it trigger an alarm so you can throw a rope net into the turbine and tie it down at a full stop. Spinning un-restained, they self-destruct. There are several terrifying videos on youtube of wind turbines, on fire, spinning to death, throwing blades enormous distances as they grenade themselves. You don't want to be that person.
A water heater tank of some hundred gallons, with NO thermostat could be used, as long as the element does not boil dry.
"Every month on average 10 wind turbines are destroyed"
http://notrickszone.com/2014/07/28/engineering-magazine-underestimated-danger-every-month-ten-wind-turbines-destroyed-by-fire/
"Only one conclusion can be drawn on the wind turbine concept: the contraptions are impractical. It’s tantamount to using 500 laborers to do the job of a single Caterpillar excavator."
Quote from: mike90045 on November 26, 2016, 11:39:35 PM
A wind turbine dump load, must be an ultra-reliable "Must Function" sort of load. It has to be rated to absorb the full hurricane power the wind turbine can output, and when that happens, I'd have it trigger an alarm so you can throw a rope net into the turbine and tie it down at a full stop. Spinning un-restained, they self-destruct. There are several terrifying videos on youtube of wind turbines, on fire, spinning to death, throwing blades enormous distances as they grenade themselves. You don't want to be that person.
A water heater tank of some hundred gallons, with NO thermostat could be used, as long as the element does not boil dry.
"Every month on average 10 wind turbines are destroyed"
http://notrickszone.com/2014/07/28/engineering-magazine-underestimated-danger-every-month-ten-wind-turbines-destroyed-by-fire/
"Only one conclusion can be drawn on the wind turbine concept: the contraptions are impractical. It’s tantamount to using 500 laborers to do the job of a single Caterpillar excavator."
Hello Mike,
Thanks again for the reply and the article. I read the article and the comments on it. The wind portion is very small and was only seen as a night-time style backup solution to produce some power to the battery banks when the solar is not running. The cost is very minimal, at less than $400 per unit setup (about $240 per wind generator w/controller and then $87 for a 100' 10 gauge 3 wire industrial style extension cord as the wire run and then the misc. parts). These are not large turbines, with the blade spans being only around 5' diameter. I also took into consideration the area wind speeds, which are not a lot here. I can't remember the exacts, but I think the average wind speed for my location is around 8-12 mph. We just had a storm system pass through yesterday afternoon and had gusts to maybe 20 mph here at the coast. So I certainly understand the many factors that can play in this arena. Luckily, I am in a location where weather factors are extremely stable .. that's why I chose here to live. Especially the temperature factors, with typical year around temps only vary about 10 degrees. Typical winter temps (like now) sit around high of about 70 and low about 50 with few exceptions and summer highs about 80 and low around 60 with few exceptions. Not only is it very predictable for things like solar and wind, its very easy on an old body. :)
Wind was the only thing I could find as an alternative for night time power generation. Would you have any other recommendations?
Also, you had mentioned a backup generator, which I do have. I fire it up about once a month for about 30 minutes, just to keep it running. I have had it about 2+ years now and it still fires up by the second or third pull. its only a small 3500 watt unit and portable. I got it on sale for about $180. But you had mentioned using it for the Jacuzzi motor. I have not fired up the Jacuzzi motor on the battery banks yet, but wondered if you knew what kind of draw I can expect on this portion, since you had brought that up?
I'm still wondering the best style setup, having the two main battery banks (right now two sets of 8 Trojan T105 RE's) and was thinking of having one bank for the big items, like refrigerators/freezer, water pump (which is a small 1/2 hp but have a pressure tank in-line as well to reduce usage and don't run much, a typical shower per day and plan the occasional Jacuzzi bath) and the other bank for all the small things, like TV, stereo, LED lighting, etc.
Your thoughts? :)
Thanks again,
SouthPacific
First, what is the inverter you are using ? Can it supply the large loads like the jacuzzi and it's heaters, and your water pumps ?
The more sophisticated inverters can also double as battery chargers. Some can even assist a generator if the loads are too much for the programmed size of the generator.
Battery banks. Generally, hook-up and use all the batteries, all the time. Trying to "reserve" some only increases the wear and tear on the others.
Alternative charging. There is wind, hydro and solar thermal. Not much else unless you build a steam engine and generator for it to spin. if your winds are generally under 20mph, there's not much energy there to bother to harvest.
Quote from: mike90045 on November 27, 2016, 03:45:51 PM
First, what is the inverter you are using ? Can it supply the large loads like the jacuzzi and it's heaters, and your water pumps ?
The more sophisticated inverters can also double as battery chargers. Some can even assist a generator if the loads are too much for the programmed size of the generator.
Battery banks. Generally, hook-up and use all the batteries, all the time. Trying to "reserve" some only increases the wear and tear on the others.
Alternative charging. There is wind, hydro and solar thermal. Not much else unless you build a steam engine and generator for it to spin. if your winds are generally under 20mph, there's not much energy there to bother to harvest.
Hello Mike,
Thanks again for the replies.
I have two inverters at present, both identical. 24v 3500/7000 units. My two battery banks are 24 volt (one in use, other about to be hooked in) with 8 Trojan T105 Re's in each. Wired with 2/0 copper, proper lugs and custom cut lengths almost all under 12" long. The 8 batteries are in 24 volt series with a single parallel setup, giving more amp hours. Both banks will be in constant use. My plan was to have all the light loads on one bank (TV's, laptops, LED lights, etc., plus the quick heavier loads, like the microwave (which is rarely used and when used only a few minutes at a time). The second bank I planned to dedicate for the constant heavy loads, like the refrigerators/freezer, water pump (a single 1/2 hp pump that does not get much work). So both banks will be in constant use. I also have 4 12 volt gel batteries I plan to use as a very light load extra, with a small controller and a single panel as a very small 12 volt setup with a 12 volt inverter I have had for a year or so, but all in perfect shape.
And just a note, the Jacuzzi I have is a tub, not a big multi-person unit. Its a 3'x5' tub, with, I think, a 1 hp motor. It does have 10 jets however, which I really like over the standard 4-6 jets. So you may have been thinking of one of the big units. I know that can be a huge factor in draw.
Yes, the wind is not much here. The turbines I have are "rated" (which we know those can be very far off) for peak efficiency at 12 mph and claim 600 watts peak), so I figure is I can get 400 watts during the night, its better than nothing. No hydro for here as well.
Your thoughts from here? :)
Thanks again,
SouthPacific
It looks like there is not really much advice anyone can give you as you are already comitted to two 24volt battery banks and each is multiple parallel battery strings, you have invested in 24volt inverters and you have decided on loads applied to each 'system'.
I agree with Vic's previous comments and advice.
If doing this design again then 48V single battery bank, single string of cells, would have been the best solution, bigger 48v inverter and Midnite 150 MPPT controller pluse epanel and solar combiners
Also one 1Kw wind turbine.
So since you have decided on your basic configuration the only useful advice I can think of is to use Midnite Classics for each battery bank, with WBjr battery current monitor. Each of the turbines should be direct wired to the DC distribution on Epanel but before the WBjr so that the current provided by the turbine can be monitored. The turbines are so small that you are unlikely to need any load diversion or Clipper hardware. They are still useful for those bad weather but windy days to get something into each battery bank.
I see they are 3phase output AC turbines so forget their controllers, just wire via a 3 pole shutdown switch then 40 amp 3phase rectifier then rectifier DC outputs to Epanel DC in terminals (where Classics connect to). I think MN have a turbine shutdown switch.
Using the Local App you should be able to monitor what is happening on each system, or better still use Graham's app on an Android tablet.
dgd
Quote from: dgd on November 27, 2016, 10:33:20 PM
It looks like there is not really much advice anyone can give you as you are already comitted to two 24volt battery banks and each is multiple parallel battery strings, you have invested in 24volt inverters and you have decided on loads applied to each 'system'.
I agree with Vic's previous comments and advice.
If doing this design again then 48V single battery bank, single string of cells, would have been the best solution, bigger 48v inverter and Midnite 150 MPPT controller pluse epanel and solar combiners
Also one 1Kw wind turbine.
So since you have decided on your basic configuration the only useful advice I can think of is to use Midnite Classics for each battery bank, with WBjr battery current monitor. Each of the turbines should be direct wired to the DC distribution on Epanel but before the WBjr so that the current provided by the turbine can be monitored. The turbines are so small that you are unlikely to need any load diversion or Clipper hardware. They are still useful for those bad weather but windy days to get something into each battery bank.
I see they are 3phase output AC turbines so forget their controllers, just wire via a 3 pole shutdown switch then 40 amp 3phase rectifier then rectifier DC outputs to Epanel DC in terminals (where Classics connect to). I think MN have a turbine shutdown switch.
Using the Local App you should be able to monitor what is happening on each system, or better still use Graham's app on an Android tablet.
dgd
Hello dgd,
Thanks very much for the reply. :)
Honestly, I'm not truly committed to much. That's why I am here. Even though I have the equipment, I can change things out without much problem. Luckily I have the resources to simply buy something else. When I started all this, I picked up the batteries first, finding what was a good local deal on the Trojans. Now, after much more research, I wish I would have gone with the larger battery configuration of the same line, but figure I can still get decent use out of what I already have for several years.
All the extras I have I can easily re-sell locally, because there are a lot of people nearby with little to no power. I already have people interested in the extra panels and I will actually be making a profit there, since I bought a full pallet (24) and got a good price at only .52/watt.
I have an array of 12v and 24v inverters and controllers as well, so getting rid of those for what I paid for them is not a big concern.
So I am basically still open for change and finding out the best design for the solar setup. The wind situation is not a priority, since I got those very cheap and those are nothing more than a night time solution to get even a little power during the night, with the main concern of keeping the battery banks in the best condition possible.
Luckily, we have a huge amount of sun here. Very little rain and very temperate climate year around, so that takes care of many factors most people have to consider.
I have designed my solar array on a tilt style platform. I live on a pretty steep incline, with the sun coming over the hill in the am. I can make the solar platform almost flat to begin catching the morning sun, then tilt from flat to the west (towards the ocean) to maximize the direct line of the sun, even down to sunset. It will also pitch at the north end to better track the sun within the seasons. I am hoping between a good MPPT controller and the use of direct angle to the sun, I can maximize the power (again, just a thought, I am an extreme novice here). So this is more of a "science project" for me, but appreciate and encourage all the suggestions/advise from those like you who know a LOT more about all this than I. :)
One question would be is if I go to a 48v setup, will two banks of 8 T105 RE's be sufficient to run everything I have listed? Or should I run the 16 I have now as a 48v in series with a single parrele between those and get another bank of the larger Trojans as my second bank? Or is there a better storage array that is still cost effective?
Thanks again!
SouthPacific
SouthPacific;
Not to jump on you but after seeing your post that nothing is set in stone hardware wise and drawing from personal experience:
Just go 48 volts to start and you will not regret it! The old, often cited, reasons to not go to 48 volts are no longer valid.
Stay away from batteries in parallel if at all possible. Many reasons for this but mostly connection resistance and hard to keep them in balance.
Use one battery bank unless you have very good reasons to use multiple banks like distance from point of use or something like that.
Maybe sit down and do some calculations on your needs. A Kill-a-watt can help if used wisely, especially on things like refrigerators / freezers that run intermittently. Use the nameplate rating on appliances and hours of use to come up with your consumption on items you know your use hours like TV, music & computers.
Careful design considerations will make the difference between a sweet system that does what you need and expensive paperweights in your yard and basement.
My best advice is to slow down and ease into things rather than go fast and loose.
Just my opinions, apparently shared by some in this thread.
Tom
Instead of doing a lot of playing with the panel angles and direction, I suggest you research 'Virtual Arrays'
Here is an example:
http://kb1uas.com/mnsforum/index.php?topic=2321.msg21910#msg21910
or do a more global search. then you can use some of those extra PV's
Quote from: TomW on November 29, 2016, 09:15:13 AM
SouthPacific;
Not to jump on you but after seeing your post that nothing is set in stone hardware wise and drawing from personal experience:
Just go 48 volts to start and you will not regret it! The old, often cited, reasons to not go to 48 volts are no longer valid.
Stay away from batteries in parallel if at all possible. Many reasons for this but mostly connection resistance and hard to keep them in balance.
Use one battery bank unless you have very good reasons to use multiple banks like distance from point of use or something like that.
Maybe sit down and do some calculations on your needs. A Kill-a-watt can help if used wisely, especially on things like refrigerators / freezers that run intermittently. Use the nameplate rating on appliances and hours of use to come up with your consumption on items you know your use hours like TV, music & computers.
Careful design considerations will make the difference between a sweet system that does what you need and expensive paperweights in your yard and basement.
My best advice is to slow down and ease into things rather than go fast and loose.
Just my opinions, apparently shared by some in this thread.
Tom
Hello Tom,
Thanks for the reply. :)
I had placed a Kill-O-Watt meter on my line and I use a base of 7.1 kw in 24 hours. This includes all my basics, including 2 refrigerators and a stand up freezer. I ran my typical things during that time, like TV, lights, etc. this does NOT include things like running the Jacuzzi tub (it is an actual bathtub, not a big multi person unit) or my music equipment (which when ran can take up some juice, because a single receiver can be 800 watts and add in dual subs at 400 watts each can be like running a big microwave for an hour or two).
So that is where my needs get a little more complicated. My base things are no problem. It's when I want to run all my "extras", I want enough juice to run those at any given time as well.
You mentioned not using parallels, but with my battery banks, I have a total of 16 Trojan T105 RE's, which placing 8 in series will give me a single 48v bank. Would you recommend I then run a single parallel between those to keep it all at the 48v? Or simply make two banks? And with such banks, will my 2/0 cabling work or will I need larger than that?
Thanks again,
SouthPacific
Not sure how others would do it but I would parallel pairs of batteries and then put those pairs in series rather than 2 strings attached at both ends. If that makes sense? Using the shortest connections possible everywhere but especially between the parallel pairs.
This would make it much easier to isolate imbalances in battery capacity. I think.
Anyway those are my thoughts on that
Tom
Quote from: Westbranch on November 29, 2016, 12:29:33 PM
Instead of doing a lot of playing with the panel angles and direction, I suggest you research 'Virtual Arrays'
Here is an example:
http://kb1uas.com/mnsforum/index.php?topic=2321.msg21910#msg21910
or do a more global search. then you can use some of those extra PV's
Hello Westbranch,
Thanks for the reply. :)
My design for this portion is really very simple. I'm located on a pretty steep hillside, with absolutely no sun obstructions (except for the hill itself in morning sun). But typically we still get the direct sun pretty early and have a clear shot of sun all the way into the ocean. So, my thought was to build a solar platform that simply follows the roof-line and roof pitch. I have drawn up a very rough sketch to try to show the design and attached it here.
The implementation of such a platform is very basic and simple. A flat platform for only 8 panels. The platform will be able to be flat in the am hours, then tilt/pitch using only 3-4 extension rods and follow the existing roof pitch until it stops. Then reset at night back to flat for the am again.
Since I have not put the top on the actual building yet, I can make the pitch conducive for the best solar angle as well. And with only 8 panels, it should not be too tough. There will also be a single pitch point on the north end that will be manually set for seasonal pitch.
Does this look do-able without much trouble?
Thanks,
SouthPacific
Quote from: TomW on November 29, 2016, 01:07:26 PM
Not sure how others would do it but I would parallel pairs of batteries and then put those pairs in series rather than 2 strings attached at both ends. If that makes sense? Using the shortest connections possible everywhere but especially between the parallel pairs.
This would make it much easier to isolate imbalances in battery capacity. I think.
Anyway those are my thoughts on that
Tom
Hello Tom,
Thanks again for the reply.
I'm a little confused on your answer here. You say to parallel batteries, then series? Not sure what you mean on that.
The area I have the battery banks is limited, in which 8 fit perfectly in each "bay", so if I were to go 48 volt, the connection between the two banks would be about 4 feet. The current configuration, I have custom made 2/0 cabling, almost all less than 12" long, most all probably 8" or so, just enough to go from battery to battery. I knew I was going to have a lot of cabling, so I bought the actual raw cable, lugs and special big cable crimping tool, since I knew I was going to be doing a lot of this and wanted to keep the shortest distances of cable in the strings.
Attached is the configuration I found for one total bank at 48 volt, which is all series with the single parallel.
Thanks again,
SouthPacific
I can't really explain better.
If you have 8 6 volt cells just find a new home for your 24 volt inverter and be smart and go to 48 volts if your panels and controllers can get there, of course.
In case you don't know this those batteries have the same energy capacity in 24 volt configuration or 48 volts. You will not lose or gain any capacity going 48 volts. 48 volts will be a more sane approach to using 8 6 volt units.
Do not make the mistake of designing around a "cheap" component that creates higher costs to actually use said component. Been there, done that and it can be a major headache and false economy.
I really don't care one way or the other but you seem to have decided on a path and I don't think I have energy or time to convince you to put it in neutral and think over the options with a view to long term success.
Don't take my word for it, look at the rest of the replies.
My only interest is seeing folks have success in their projects with a minimum of grief.
Tom
Quote from: SouthPacific on November 29, 2016, 02:15:46 PM
Quote from: TomW on November 29, 2016, 01:07:26 PM
Not sure how others would do it but I would parallel pairs of batteries and then put those pairs in series rather than 2 strings attached at both ends. If that makes sense? Using the shortest connections possible everywhere but especially between the parallel pairs.
This would make it much easier to isolate imbalances in battery capacity. I think.
Anyway those are my thoughts on that
Tom
Hello Tom,
Thanks again for the reply.
I'm a little confused on your answer here. You say to parallel batteries, then series? Not sure what you mean on that.
The area I have the battery banks is limited, in which 8 fit perfectly in each "bay", so if I were to go 48 volt, the connection between the two banks would be about 4 feet. The current configuration, I have custom made 2/0 cabling, almost all less than 12" long, most all probably 8" or so, just enough to go from battery to battery. I knew I was going to have a lot of cabling, so I bought the actual raw cable, lugs and special big cable crimping tool, since I knew I was going to be doing a lot of this and wanted to keep the shortest distances of cable in the strings.
Attached is the configuration I found for one total bank at 48 volt, which is all series with the single parallel.
Thanks again,
SouthPacific
Only a little time, just now.
1. Of course, you will want a 48 V system.
2. The 48 V battery config for two strings of batteries is fine. Two strings = not good, but that is what you have now. Single string of batts is much easier to manage, and works better.
3. The four foot separation twix the two strings is NOT good.
4. You will want to have quite a bit more space for batteries for your future configuration.
5. Sevenish kWh consumption is quite a lot for an off grid system.
6. Strings of four of those PVs puts you in the territory of a Classic 200. How about considering strings of three of your existing PVs? Probably would be three strings of three, instead of two strings of four. You would need that Combiner/breakers with three or more strings.
7. YES, sell the 24 V stuff, and maybe those batteries, too ...
And so on. FWIW, Vic
Quote from: TomW on November 29, 2016, 02:54:01 PM
I can't really explain better.
If you have 8 6 volt cells just find a new home for your 24 volt inverter and be smart and go to 48 volts if your panels and controllers can get there, of course.
In case you don't know this those batteries have the same energy capacity in 24 volt configuration or 48 volts. You will not lose or gain any capacity going 48 volts. 48 volts will be a more sane approach to using 8 6 volt units.
Do not make the mistake of designing around a "cheap" component that creates higher costs to actually use said component. Been there, done that and it can be a major headache and false economy.
I really don't care one way or the other but you seem to have decided on a path and I don't think I have energy or time to convince you to put it in neutral and think over the options with a view to long term success.
Don't take my word for it, look at the rest of the replies.
My only interest is seeing folks have success in their projects with a minimum of grief.
Tom
Hello Tom,
Thanks again for the reply. I'm not sure what made you think I have a "path" selected, but I can assure you I don't at this point and any and all advise is greatly appreciated. :)
So you are saying my best route would be going 48v, but run 2 banks (8 X 6v batteries) and not parallel the two 48v banks?
My panels are the CSUN 305's and have many extras, so I can place into any style of configuration. It's the controller that I am most confused about to make the most efficient setup in that regard. Being a higher powered panel, finding the right controller is very important. And I'm not looking to go go "cheap", but do want to find the best value for the long haul.
Thanks again,
SouthPacific
Quote from: Vic on November 29, 2016, 03:50:38 PM
Only a little time, just now.
1. Of course, you will want a 48 V system.
2. The 48 V battery config for two strings of batteries is fine. Two strings = not good, but that is what you have now. Single string of batts is much easier to manage, and works better.
3. The four foot separation twix the two strings is NOT good.
4. You will want to have quite a bit more space for batteries for your future configuration.
5. Sevenish kWh consumption is quite a lot for an off grid system.
6. Strings of four of those PVs puts you in the territory of a Classic 200. How about considering strings of three of your existing PVs? Probably would be three strings of three, instead of two strings of four. You would need that Combiner/breakers with three or more strings.
7. YES, sell the 24 V stuff, and maybe those batteries, too ...
And so on. FWIW, Vic
Hello Vic,
Thanks again for the reply. :)
Ok, so 48v it is. :) But I am a little unclear on your statement on the strings. I'm using 2 bays, each holding 8 of the 6v Trojans, so when I series those it makes the 48v bank. The parallel cabling going between the 2 48v banks I could get as short as about 2 feet with a little wall drilling. You also mentioned "The 48 V battery config for two strings of batteries is fine. Two strings = not good, but that is what you have now". Is there another configuration for a 48v system? I have read about people using forklift batteries that are 2v cells.
I had never really checked into the typical loads of an off-grid system, but at 7.1 kw per 24/day, that will put the 30 day load around 215 kw per month. When I checked a typical usage chart for housing, a 1 bedroom 750 sq ft apartment typically ran about 700-800 kw per month (more if using ac and such). What does a typical off-grid system use for a house? I am running 2 refrigerators and a large stand-up freezer, all being new and Energy Star, but most everything else is minimal. 1 TV and 2 laptops, router, etc and some LED lights the huge majority of the time.
Now going with the 48 volt setup, what would you recommend as to how many panels in what configuration (I have the CSUN 305's) and going into the combiner box and what would be the best controller(s) to run? And for what I am wanting to run (since you said my usage for an off-grid system is high), should I had more storage..and if so, what would be the best configuration to use here?
Thanks again,
SouthPacific
SP, I just read all of today's posts right now and there is some confusion between all of us.... not sure but I think it is because we need to see a list that clearly tells us of all the bits you have and what you intend to buy...
The best place to put it is in you sig line. Please?
As to the PVs I am saying use some (3 or 6) PV's FIXED in the AM position and similarly for the PM< FIXED. Don't muck around with changing the direction daily, it's a PITA. Though you could have an adjustable option for different seasons... or if you have > 3 days with poor solar insolation.
WHY Virtual Arrays?
You say you have extra PV's handy, use them and orient them to optimize for the winter period as that is your critical time for making sure the batteries are fully charged...
In the summer you will have more input than you probably need, I sure do...
The battery layout you show is designed for ONE Charge Controller, not 2 as you state at the start of this thread. It is called 8S 2P, 8 in series with 2 parallel strings (of 8 )
One of the issues is that those Trojans are not very high in Ah rating, relatively... look at my and others sig lines and you will see battery ratings above 500Ah and in 2 volt cells. I have 900 Ah cells and that amount might work for you if you have 2 batteries on separate controllers feeding separate circuits... or a single battery of ~2000Ah , depends if your loads are less than that (1000 Ah ) per day. Remember that you should not go below 50% State of Charge for the health of your battery...
hth
Quote from: Westbranch on November 29, 2016, 07:39:07 PM
SP, I just read all of today's posts right now and there is some confusion between all of us.... not sure but I think it is because we need to see a list that clearly tells us of all the bits you have and what you intend to buy...
The best place to put it is in you sig line. Please?
As to the PVs I am saying use some (3 or 6) PV's FIXED in the AM position and similarly for the PM< FIXED. Don't muck around with changing the direction daily, it's a PITA. Though you could have an adjustable option for different seasons... or if you have > 3 days with poor solar insolation.
WHY Virtual Arrays?
You say you have extra PV's handy, use them and orient them to optimize for the winter period as that is your critical time for making sure the batteries are fully charged...
In the summer you will have more input than you probably need, I sure do...
The battery layout you show is designed for ONE Charge Controller, not 2 as you state at the start of this thread. It is called 8S 2P, 8 in series with 2 parallel strings (of 8 )
One of the issues is that those Trojans are not very high in Ah rating, relatively... look at my and others sig lines and you will see battery ratings above 500Ah and in 2 volt cells. I have 900 Ah cells and that amount might work for you if you have 2 batteries on separate controllers feeding separate circuits... or a single battery of ~2000Ah , depends if your loads are less than that (1000 Ah ) per day. Remember that you should not go below 50% State of Charge for the health of your battery...
hth
Hello Westbranch,
Thanks again for the reply and I apologize for any/all confusion I have made in the thread. I new at both PV and on-line threads/forums..I don't even know how to setup a tag line.
What I have learned so far here is going with a definite 48 volt setup. So that portion is now set.
I'm a bit confused now even on my battery selection. When doing a lot of research on places like YouTube, almost everyone was talking about going 6 volt batteries and Trojans were highly rated by many, hence my selection on which batteries I started with. I did see a few people refer to using forklift batteries with the 2 volt cells, but those were people using old batteries and them reviving them, etc., so I was not real impressed with those. I do wish I had gotten the larger Trojans than these smaller T105 RE's. It seems I might as well sell them with all the other equipment for people here who have much smaller power needs.
Vic has mentioned that my power usage of 7.1 kw in a 24 hour time frame was pretty high for an off-grid system. So I am now wondering what I need to fit my needs. From other things I had read, it did not appear my usage to be even that of a standard small apartment, which averages around 700-800 kw per month and my base is around 215 kw .. so I thought I was doing ok, considering that is including 2 refrigerators and a large freezer (all new and Energy Star). This, however, is only my base and NOT running my "extras" like stereo system w/powered subs, Jacuzzi bath tub (its not a multi person style unit), etc. the 215 kw per month is strictly baseline with all my common things I use everyday.
So the only thing now for sure will be the solar panels themselves, which are the CSUN 305 Poly's.
To clarify my goal, is to build a system that is totally off-grid and properly run everything I want to run. With such a fluctuation in power needs at different times, would designing a system with 2 battery banks be a good configuration, with 1 bank dedicated to run the "everyday" baseline items and a second bank to compensate and run the "extras", like the Jacuzzi bath tub, and music equipment, which these items would only be used maybe once a week at most (this is just me thinking out loud, so any suggestions/recommendations are very welcome).
And if changing batteries, what would be the best design for my application?
Again, basically everything is open. The only for sure item is the panels themselves. I can reconfigure everything else, even the panels, but I think the panels should work fine (if I am wrong on that, please let me know)
Most of the equipment I currently have is now off the list, since I am going to the 48v setup. I do have the combiner box, which I think I can still utilize and all the solar panel wiring I have should be good (I have the 10 gauge MC4 connections, with multiple tails, up to 4 to 1) and that's about it for now.
Thanks again,
SouthPacific
here is the crux of your problem...
To clarify my goal, is to build a system that is totally off-grid and properly run everything I want to run
The first part of you statement is achievable but with limitations...
The objective, in RED, is the issue... you have outlined such high daily consumption levels, 7.1 KwHr NOT Kw, the time portion is important otherwise it is like saying I bought a 7 Kw generator and you left off the part where it burns fuel to make power...over time...
We use ~ 1.5Kwhr per day at the lake and live a comfortable life as we burn wood for heat and don't have a big 100W per channel stereo (it is still hooked to the grid in town) or a Jacuzzi for example...
and it took months to pare down what we would LIKE to what we NEED... then you start adding a bit at a time to the analysis (spreadsheet) and evaluate the impact of the additional power needed. You not only need to look at the loads in total but also the loads over time during the day and night. If 2 or 3 large loads are running simultaneously it has implications that may not matter if, say, your inverter is capable of 20Kw vs having a 2Kw inverter...and you have the storage to support it... or manual intervention is to be used to prevent killer surges occurring...
This is an exercise in self control and honesty.
If you have unlimited resources you still have to start somewhere and take a first small step... NO?
Batteries:
Most of us here have started with a SACRIFICIAL set of batteries.
WHY? Because 99% of first time solar users Will KILL their first set or 2 in short order.
Killing occurs eg, when one uses too much power at once by going to, say, 10% SoC
or NOT replacing the usage asap, ie no PV for 4 days and not running the generator on day 1...
You have to do this project systematically, start with the essential core and then do another iteration with more loads... repeat as necessary
hth
Quote from: SouthPacific on November 29, 2016, 06:02:10 PM
Quote from: Vic on November 29, 2016, 03:50:38 PM
Only a little time, just now.
1. Of course, you will want a 48 V system.
2. The 48 V battery config for two strings of batteries is fine. Two strings = not good, but that is what you have now. Single string of batts is much easier to manage, and works better.
3. The four foot separation twix the two strings is NOT good.
4. You will want to have quite a bit more space for batteries for your future configuration.
5. Sevenish kWh consumption is quite a lot for an off grid system.
6. Strings of four of those PVs puts you in the territory of a Classic 200. How about considering strings of three of your existing PVs? Probably would be three strings of three, instead of two strings of four. You would need that Combiner/breakers with three or more strings.
7. YES, sell the 24 V stuff, and maybe those batteries, too ...
And so on. FWIW, Vic
Hello Vic,
Thanks again for the reply. :)
Ok, so 48v it is. :) But I am a little unclear on your statement on the strings. I'm using 2 bays, each holding 8 of the 6v Trojans, so when I series those it makes the 48v bank. The parallel cabling going between the 2 48v banks I could get as short as about 2 feet with a little wall drilling. You also mentioned "The 48 V battery config for two strings of batteries is fine. Two strings = not good, but that is what you have now". Is there another configuration for a 48v system? I have read about people using forklift batteries that are 2v cells.
I had never really checked into the typical loads of an off-grid system, but at 7.1 kw per 24/day, that will put the 30 day load around 215 kw per month. When I checked a typical usage chart for housing, a 1 bedroom 750 sq ft apartment typically ran about 700-800 kw per month (more if using ac and such). What does a typical off-grid system use for a house? I am running 2 refrigerators and a large stand-up freezer, all being new and Energy Star, but most everything else is minimal. 1 TV and 2 laptops, router, etc and some LED lights the huge majority of the time.
Now going with the 48 volt setup, what would you recommend as to how many panels in what configuration (I have the CSUN 305's) and going into the combiner box and what would be the best controller(s) to run? And for what I am wanting to run (since you said my usage for an off-grid system is high), should I had more storage..and if so, what would be the best configuration to use here?
Thanks again,
SouthPacific
SP,
If you must run two parallel strings of batteries for a 48 V system, then the diagram that you noted, should be fine. Long jumpers (read that you needed to use four foot jumpers to connect each half of the battery together) ... that is quite long.
Off grid systems, that rely on batteries, usually need to be designed with as much energy conservation as possible. 7 kWh/day is quite a lot of consumption. This has little to do with national averages for grid-powered systems.
What time of day that the energy needs to be supplies is an important piece of information. Power supplied only from your PV array is much better than energy that needs to be supplied only batteries. Having a relatively large PV array will help with this ...
Later, Vic
Quote from: Westbranch on November 29, 2016, 09:03:45 PM
here is the crux of your problem...
To clarify my goal, is to build a system that is totally off-grid and properly run everything I want to run
The first part of you statement is achievable but with limitations...
The objective, in RED, is the issue... you have outlined such high daily consumption levels, 7.1 KwHr NOT Kw, the time portion is important otherwise it is like saying I bought a 7 Kw generator and you left off the part where it burns fuel to make power...over time...
We use ~ 1.5Kwhr per day at the lake and live a comfortable life as we burn wood for heat and don't have a big 100W per channel stereo (it is still hooked to the grid in town) or a Jacuzzi for example...
and it took months to pare down what we would LIKE to what we NEED... then you start adding a bit at a time to the analysis (spreadsheet) and evaluate the impact of the additional power needed. You not only need to look at the loads in total but also the loads over time during the day and night. If 2 or 3 large loads are running simultaneously it has implications that may not matter if, say, your inverter is capable of 20Kw vs having a 2Kw inverter...and you have the storage to support it... or manual intervention is to be used to prevent killer surges occurring...
This is an exercise in self control and honesty.
If you have unlimited resources you still have to start somewhere and take a first small step... NO?
Batteries:
Most of us here have started with a SACRIFICIAL set of batteries.
WHY? Because 99% of first time solar users Will KILL their first set or 2 in short order.
Killing occurs eg, when one uses too much power at once by going to, say, 10% SoC
or NOT replacing the usage asap, ie no PV for 4 days and not running the generator on day 1...
You have to do this project systematically, start with the essential core and then do another iteration with more loads... repeat as necessary
hth
Hello Westbranch,
Again thank you for your reply and patience with my lack of both knowledge and proper terminology.
When I referred to the Kill-O-Watt number, I simply looked at the watt meter and it read 7.1 kw at the end of the 24 hour test period, with only the basic equipment being metered in the line. Can you clarify this setting? Is that 7.1 kw use or 7.1 kw HOUR use? I know that can be a big factor just by my lack of proper reading and terminology. When I ran the test, it was a full like test that included the 2 refrigerators, the big freezer, then my single TV, two laptops, router and a few LED lights. So I am unclear of that exact spec.
That is why my line of thinking (just thinking out loud and I could be totally wrong) was to run two banks. The 1st being for just the normal baseline everyday loads I know will be 24/7 and pretty constant as to total load. Then use the 2nd bank as the "run the extras" like the music and Jacuzzi bathtub, etc. with all these things being rarely used, maybe once per week at most and most likely much less often. However they can be big draws. This way I will know what to expect from the 1st bank, being constant and much more predictable and the 2nd bank..well who knows until it is actually in use. And I understand any battery bank should never be drained more than 50%, because that will destroy your bank very quickly.
I hope this brings a little more clarity.
Thanks again,
SouthPacific
Quote from: Vic on November 29, 2016, 09:50:40 PM
SP,
If you must run two parallel strings of batteries for a 48 V system, then the diagram that you noted, should be fine. Long jumpers (read that you needed to use four foot jumpers to connect each half of the battery together) ... that is quite long.
Off grid systems, that rely on batteries, usually need to be designed with as much energy conservation as possible. 7 kWh/day is quite a lot of consumption. This has little to do with national averages for grid-powered systems.
What time of day that the energy needs to be supplies is an important piece of information. Power supplied only from your PV array is much better than energy that needs to be supplied only batteries. Having a relatively large PV array will help with this ...
Later, Vic
Helli Vic,
So basically, if I run a larger solar array and use these major draw items (like the Jacuzzi bathtub and the music items) during say daylight and even peak solar times is much better, because I will be running from the PV array and not off the batteries? So then use more panels and use those items during the daylight hours and this will save me greatly on the battery usage aspect?
Thanks again for the clarity.
SouthPacific.
getting dark here... yes the term must have the hour included.. like I go 150 miles on my Mcycle vs I go 150 Mpg...
you are getting there and as Vic says '' then the diagram that you noted, should be fine. ''
It can work for you but you need to be aware of the limitations...
And Vic also gave a different look at the timing of loads... and ''opportunity loads'' can be used to make use of power that otherwise would be ''lost'' as once your bank is nearly full, the CC will be throttling back on how much (Amps and/or Volts) is pushed into the bank... more later....
sleep on it... there is a lot to Solar 101 !
SP
Looks like your getting lots of good advice here.
Definitely go 48v and invest in the largest batteries you can get to have just a single string of cells making the 48v. From you dicussion on loads it would mot seem that a single string of L16 would not be sufficient. Something like 800ah cells would be nicer, if FLA types or 300/400ah if LifePO4 types
I also would not be in any hurry to sell off the spare PVs you have. The way things tend to work in this business is that spare PVs don't stay spare for long.
Dgd
First something slightly off topic but still important:
I often see folks use KW and KWH interchangeably. I see it in this thread, as well.
That is just plain wrong and very confusing.
I saw a good analogy the other day that I want to pass on.
KW is like the speedometer on a vehicle.
KWH is like the odometer on the vehicle.
The units are the same but they mean very different things.
now, back to your project, SouthPacific:
This thread has gotten fairly long and with so many included quotes I get lost. I will just hit the high spots here:
48 volts is definitely they best commonly available voltage for an off grid system with batteries.
A true hard core off grid system will use 2 volt cells in a single series string. This eliminates the parallel strings issue.
I used to be an advocate of tracking arrays (follow the sun). I no longer am an advocate of tracking. Simply put, it is a pain in the backside to do unless it is automated. If it is automated it is another point of failure with moving parts. Plus solar modules have gotten so cheap that you can easily put in a lot more modules than you think you need if you were tracking. And, probably for less money.
Facing smaller arrays in different directions can boost output by working around your shade issues. Basically get as many modules in full sun as much as possible. This can mean throwing out commonly held "rules of thumb" like solar panels need face south (north in the other hemisphere). Solar panels need to face the sun as much as possible. Some locations might require panels facing East,West or both if multiple arrays are used. In these cases each array should be on its own charge controller.
For big loads you may need to bite the bullet and use a fuel powered generator. That way, you are never going to be backed into a energy deficit corner choice of either no power or a battery killing over discharge as you can fire up the generator.
As stated earlier your big Jacuzzi load is pretty impractical for running from batteries.
Just from here.
Tom
Hello everyone,
Instead of trying to do all the quotes from all the recent replies, I wanted to first thank everyone for the replies and all the great information.
I'm re-evaluating the entire system at this point. I do understand that 48 volt is the definite configuration I will be building and the panels I have (CSUN 305's) should be good from that standpoint.
I am now looking at the battery bank system and found the Trojan L16RE-2V. I wanted everyone's opinion on these. In research I understand that flooded batteries are about to be a thing of the past and more efficient energy storage is coming into play. So I would also like your opinions on this matter. Should I begin to plan around the old flooded battery style or continue looking into the newer alternatives?
I think this will be a good foundation point in the design from here.
Also, the 7.1 on the Kill-O-Watt is KWH and not KW, just to clarify that. Is that still considered a lot on an off-grid system?
Your thoughts? :)
On a side note, I'll be a little less available on the forum this week. I began playing back in the market the first part of October and have some nice plays in the works, so a lot of research and watching is going into that atm. Made just over 37% in the month of October playing some oil ETF's and picked up FNMA just before the election at $1.65 .. it closed today at $4.49 and looking to continue a hard climb. So some good easy money to be made right now. :) Have to make the money for all this new PV setup.
Thanks again!
SP
So I just read this entire thread and gotta wonder.... Did you ever build the system... Or did the idea get scrapped? I was really wanting to find out if u ever found a big enough battery bank to handle such large loads.