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General Category => System Design and Layout => Topic started by: UpNorthMan on December 11, 2017, 09:27:18 PM

Title: Layout of a new 800w system
Post by: UpNorthMan on December 11, 2017, 09:27:18 PM
Hello Everyone,
I’m relatively new to solar power system and could use any wisdom you are willing to share. We are building a 800w 24v system for our off grid cabin in northern MN. I have purchased 8-100w Renogy mono panels and a Midnite Kid with temp sensor. As I understand, I should hook up in a 2, 4 (S, P) configuration to keep the temp down on the CC. I can also configure the panels in a 4, 2 configuration. I also am not opposed to buying one more panel to get a 3, 3 configurations if it makes more sense. The temp range is 105 F to -45 F or colder. It is not unheard of being colder than -50 F in the morning right after sunup. This is actual temp not wind-chill.  The panels will be mounted on a south facing wall with manual adjustments for angle. Shade is not a problem except for the end of the day or in the middle of the winter when the sun is low in the sky. My eventual plans are to use the load feature to heat the batteries in the winter months and a heat sink hot water heater system. If I use the 2,4 configuration, I understand my leads need to be the same length and will be 30-40 feet long. I want to keep my combiner box inside the cabin. My loads consist of 1 c-pap, .8amp 120v fridge, and the remainder is lights and radio. I’m planning on having 2- 210AHR 12V batteries. The Renogy panels have the following specs:  max power 100W  Voc 22.5V Vmp 18.9V Imp 5.29A Isc 5.75A
The Kid sizing chart is ok with both 2, 4 and 4, 2 configurations. I have the following questions:
1)   What panel configuration would be best?
2)   Is a SPD required? If so what size?
3)   Is this type of system required to be grounded?
4)   I’m looking at buying a pure sine inverter. Does a modern inverter use 100% input wattage under 10% load, or does a inverter only use required load watts plus conversion loss? I like to have a 2000W inverter for other misc loads that may happen.
5)   Is there anything that I missed that you would recommend?  I know fuses, correct wire size, and disconnect switches are required.
Thanks in advance,
Ed
Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on December 11, 2017, 10:44:50 PM
The general rule of thumb when planning out the series / parallel combination of panels is to try and keep the PV voltage closer to the battery voltage if possible because then the controller is more efficient and won't get as hot. But if you need the higher PV voltage because the  run from PV to cabin is long and you need higher voltage to reduce wire size , then that is a design consideration.

The other main consideration to how many panels you can put in series is the VOC during those very cold nights.
The Kid string sizing calculator should show you all the various options and what will work with the Kid.

Why do you want the combiner to be inside far away from the panels ? That kind of defeats some of the benefit of the combiner because you can run one pair of larger gauge wires for lower voltage drop back to the cabin instead of the 4 or 6 you seem to be wanting to do ?

Consider getting a Midnight Mini DC disconnect box . It will make wiring your Kid and inverter a lot easier and has breaker for inverter and spaces for the  PV , Bat , and DC load breakers as well. If you ever think of upgrading to something like the Classic for more PV ( and much better monitoring ) then it would be easy to swap out controllers. The Mini DC box also has spot to put the shunt with the Whizbang .  So if you get the MiniDC box you will have to know ahead of time which inverter you would get so you order the one with the right size breaker for the inverter.

yes you usually ground your system - all to the same ground rod so the potential is the same on all of them.  You will have to look up grounding . On my system I have ground wire coming from combiner box to ground rod and the controller , inverter cases and AC neutral are all grounded to it . It is a rather confusing topic in some ways so read up !

You can get the Midnite SPD  - one for the PV side and you can put one on the AC inverter side . You don't really need them but they are extra protection in case you ever get surges from nearby lighting strikes. If you look them up you will see the voltage ratings and you can use any one with the voltage rating for you system.

Consider getting an inverter with built in charger so you can hook a generator on it and charge your batteries. That is an essential part of the system in Minnesota and a lot of other places too. Otherwise you will have a short life time on your batteries. Ideally for long lifetime of batteries you only want to drain them 20 or 30% and they will last much longer. That doesn't sound like a lot of battery capacity for running a fridge in the winter if you are planning on doing that . So when your batteries get discharged by 30% if it isn't sunny out charge them with the generator. 

yes  your inverter will draw some power even when there is no load - depends on which inverter you get - specs should show no load current draw.  And then a modern inverter should be 80 to 90% efficient depending on the size of the inverter and the size of the load. Most inverter companies will show those efficiency graphs in their literature .

You asked a lot of questions - this is my summary answer !
Larry

Title: Re: Layout of a new 800w system
Post by: UpNorthMan on December 12, 2017, 04:14:24 PM
Thanks Larry! I appreciate the input! I'll try to explain some more of my thoughts.
In the winter, I plan on using mother nature for a fridge. A cooler in the porch has worked well in the past. It's been more of a concern of stuff freezing than anything else.
As far as the configuration, the 2,4 with all the extra accessories to do it right would cost an extra 500 $. I'm not trying to be cheap, but I could use that money elsewhere. I believe that the 4,2 configuration could be done with a inline fuse and a standard connector. Please correct me if I'm wrong.
If the CC runs warm, but not hot, I wouldn't be afraid to run a pancake fan on it. If it is likely going to run hot, then the extra money will be worth it.
I want to have the combiner box inside so I don't have to worry about anyone messing with the system. The cabin is located in the woods and vandalism or mischief has been a problem for a couple of the distant neighbors.
For the near future, this will be a weekend cabin, and the occasional week long stay.
I hope this helps with the discription of the direction I'm going with the system.
Ed
Title: Re: Layout of a new 800w system
Post by: Vic on December 12, 2017, 04:58:28 PM
Hi  U N M,

The PV String configuration can also be dictated by the exact battery that will be used on the system.

With your mention of a 210 Ah 12 V battery,  perhaps you might be thinking of using a 4D AGM.   AGM batteries do not require high Absorb or "EQ" voltages.   This can mean that the KID (or other MPPT Charge Controllers (CCs),   will be able to find a generally effective Max Power Point voltage, which would maximize power production from the PVs under most any set of conditions.  Some AGM batteries  need only a fairly narrow range of charge voltages verses changes in battery temperature.

If you are planning on using Flooded Lead Acid (FLA) batteries,  it would be quite possible that strings of 2 PVs in series would not provide the CC sufficient headroom to produce optimum power output.

Exactly what brand and model number of battery are you planning to use?

Thanks,    Vic
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on December 12, 2017, 06:54:48 PM
Hello Vic,
The actual battery I was looking at was Trojan J185H-AC  12V 225 AH Battery
This would be 225 Ah not 210 as my original post.
The specs per cell are
absorption 2.35-2.45v
float 2.2V
equalize 2.58v

The specs for series (24v)
absorption 28.2-29.4v
float 26.4V
equalize 30.96v

I haven't looked to hard to find a local distributor, but one 10 hrs away has some at a reasonable price. I live 45 miles NW of Brainerd MN.
I haven't made up my mind if these are the ones I am getting. Price and quality seem to be what I'm looking for. I am open to suggestions, but these are what I'm leaning towards.

Ed
Title: Re: Layout of a new 800w system
Post by: Vic on December 13, 2017, 08:19:57 PM
Hi Ed,   Thanks for the added info on the batteries you are considering for the system.

In looking at this Data Sheet:
http://www.trojanbattery.com/pdf/datasheets/J185HAC_Trojan_Data_Sheets.pdf

The  Absorb voltage is very close to what you mentioned,   but the EQ voltage is 32.4 V.   The EQ voltage (Veq)  is high,  which can mean several things  ...   It might not be possible to EQ your batteries with common,  inexpensive Inverters,  perhaps ever,   and,   with cool/cold batteries  EQing batteries,   even with the "best" inverters might not be possible.

Also,  you will need to look at the  MNKID String Sizer results,  particularly for warm/hot weather.   In warmer weather,  it might not be possible to reach even Absorb voltage (Vabs) with strings of two PVs,   let alone,   when trying to EQ.

It is customary to design string configurations with a minimum  Vmp string voltage of about 30% greater than highest battery charge voltage that the system will ever see.   Generally for FLA batteries,   this would be EQing cool/cold batteries.

For cool batteries,   charge voltages need to increase,   and for warm ones,  the opposite is true.   Your proposed Trojan batteries need this Temperature Compensation of Charge voltages needs to be compensated (by that KID Battery Temp Sensor  --  BTS) at  -5mV per battery cell,  per degree C for temperatures below about 27 C,   and above 27C,  by reducing charge voltages by that factor  --  this is built-into the KID Firmware,   as you probably know.

DO look at the ambient temperature where the KID reaches HyperVoc with strings of three PVs.  This should be at a very,   very low temperature,   but just check it,  please.

More later,  Vic
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on December 14, 2017, 06:29:40 PM
Vic,
Thanks for sharing your knowledge!
I'm wondering if I referenced a older spec sheet.The info I posted was correct per the data sheet from the suppliers website. I'll use the values directly from the manufactures. Good catch on values ;D ;D
Bulk 29.64 v
float 27.0 v
equalize 32.4 v
As far as the battery temp in the winter, I was going to try and stay around 55F. I was going to have removable insulating panels on my battery box. Use extra venting in the summer and much smaller in the winter. 24v cartridge heater 100w?? in size with a thermostat. I've been a machinist for many years an have access to the equipment for personal work.
I've run the numbers for all 3 setups. 2,4 and 4,2 come out OK. 3,3 is where the Kid doesn't like it. 841 watts/31.3 amps, Kid requirement of 1.1 With the cabin located at 48.25 degs north, I most likely won't get full production. From what I've read, it sounds like the Kid can handle extra input watts. It just won't  output any more then the 30a @ 24v With 8 100w panels and 24v batteries, the output power is 27.8A per the sizing chart.

The HyperVOC values for 24V are as follows
2,4 -1323.4 F
3,3 -655.6 F
4,2 -322.6 F

It appears that 2,4 are out of the equation, the panel output voltage is to low under certain conditions.

I choose the current panels because of there physical size/shape as they relate to the planned mounting on the cabin.
Another thing I am considering is that I am maxing out the CC in 24V mode. There won't be any room to expand except by purchasing another. It might make sense to go to 36V or 48V system. I could buy smaller A-hr batteries. 48V seems to be the next step. From what I've seen, 36V isn't the most common.  If I went to a 48V system, it looks like two more panels. If my math is correct, 84V min for batteries figured 77F with a1.3 factor, add up to 8V more for cold battery extreme. With a 4,2 configuration, only 75.6 V VMP.  I don't require 24V for any certain appliance. I don't recall the name of the device, but a voltage reducer from 24/48V to 12V would work for me. 12V led lighting, radio, pumps, ect are very common.  A 12V 25 amp load would be a very heavy load. The biggest load would be the addition of a compressor fridge, and that would be on a inverter.

Below is the calculated values for a system in my area.
(//)


I currently share a cabin with two brothers, we have a tiny 100W system that we have been using for a couple years. It has given me some limited incite on usage, capacity, and conservation.

Many things to consider!! The good thing is that I don't need to have my mind made up until April/May at the earliest.

Ed
Title: Re: Layout of a new 800w system
Post by: mike90045 on December 16, 2017, 01:14:35 AM
Quote from: UpNorthMan on December 12, 2017, 04:14:24 PM
....I want to have the combiner box inside so I don't have to worry about anyone messing with the system. The cabin is located in the woods and vandalism or mischief has been a problem for a couple of the distant neighbors.....

Those big shiny PV panels are vandal bait.  Expect losses.  Copper wire is easily re-sellable, boxes, not so much.
Title: Re: Layout of a new 800w system
Post by: CDN-VT on December 18, 2017, 10:37:51 PM
VOC is system voltage plus rated unit !!!

So a classic 150 is adding 48 Vdc so VOC is 198Vdc MAX from panels

150 + 24Vdc system is 174Vdc

JFI

VT

Title: Re: Layout of a new 800w system
Post by: UpNorthMan on December 23, 2017, 10:24:05 AM
Thanks for the info!
Title: Re: Layout of a new 800w system
Post by: CDN-VT on December 23, 2017, 09:25:03 PM
The biggest load would be the addition of a compressor fridge, and that would be on a inverter.

Danfoss is one good compressor system & they are in many units in chest freezer to coolers .

With the use of a Kill-a-watt & measure the freezers & I use a freezer as a fridge with a different Johnson thermostat system .
Cuts the KW down to 1/3 less from freezer & frost free fridges draw the most .

JFI
VT
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on December 28, 2017, 04:12:42 PM
I've read that somewhere else, that sounds like a interesting idea that I'll have to put on my list to research.

Right now I'm trying to find some acceptable DC light switches, 12v or 24v system. From the my research, it sounds like the older snap light switches are compatible. The other option I've read about is via circuit breakers. I am planning on using 10amp breakers in a MNPV12 and a extreme switch load would be 36w. Most would be around 15w. I like the traditional setup used in AC wiring, a switch by point of use. And I would rather not wire everything as AC. I don't want the inverter running all the time.

I did come across a manual motor on/off switch from Square D model# 2510KO1
I don't know if they are legal. Anyone have any thoughts?
See link below for specs.
https://www.schneider-electric.us/en/product/2510KO1/manual-switch---open---2p---toggle-operated---no-indicator---600vac-/?range=7476-type-k-manual-switches&node=166379550-2510k-manual-switches (https://www.schneider-electric.us/en/product/2510KO1/manual-switch---open---2p---toggle-operated---no-indicator---600vac-/?range=7476-type-k-manual-switches&node=166379550-2510k-manual-switches)
(https://download.schneider-electric.com/files?p_Doc_Ref=2510KO2&p_File_Ext=.PNG&p_File_Type=rendition_200_png&default_image=DefaultProductImage.png)

There are a lot of auto/marine products out there, but I am trying to keep the system as close to code as possible. So I'm assuming those products are out due to wiring code.


Does anyone have any suggestions on any DC products?

Ed
Title: Re: Layout of a new 800w system
Post by: CDN-VT on December 30, 2017, 01:30:15 AM
12 Vdc or 24Vdc , controlling WHAT ?
Low light amps  ? 
you need to remember  , cars use relays  for 15-25 amps and are just contacts .
It's not till you reach voltage that will draw an ARC !! .

Then again many Square D breakers are DC rated in the Pro series (Silver contacts  )

If you can rethink the lighting grid & use a SS300 @ 120Vac  , then ?
Use lowes stuff !

VT
Title: Re: Layout of a new 800w system
Post by: mike90045 on December 30, 2017, 03:02:01 AM
I think after all the mess trying to wire for 12V lighting, just get a morningstar sure sine 300w inverter and hard wire it, and use conventional.  300w will run a lot of lights and cell chargers
Title: Re: Layout of a new 800w system
Post by: CDN-VT on December 30, 2017, 09:12:28 PM
I agree on the SS300 , with that system hard wired & just use for lighting with regular switches (none back lit ones, causing a draw) So when all lights are off the ss300 should go to sleep . Using some led types the ss300 in search mode might make the led wink , so what I did was use SPDT type switches . As for LED tubes 22watt 120Vac ones , I haven't seen a wink.

Best is to test first & then see how to wire them in using standard 14/2  lumax/romax

VT
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 01, 2018, 06:42:44 PM
I'll take your advice!!! I wasn't real excited with the dc wiring anyway. I was just trying not to have the larger fridge Inverter running all the time. I am looking at purchasing a 1500W Aims PS inverter because of my fridge. I am only planning on using it during the warmer months. Winter up here makes more then enough ice. It was -32F this weekend. So would you recommend a smaller inverter to run  my lights and ect... And a separate circuit to run my larger loads? I haven't finalized my battery voltage. Still on the fence about 24 or 48 volts. The efficiencies aren't as favorable with the larger inverter. Or am I over thinking it? Any thoughts?

Ed
Title: Re: Layout of a new 800w system
Post by: CDN-VT on January 01, 2018, 08:58:47 PM
over thinking it?
Yes , 48Vdc & since you have a fridge now & whats next , buy a good inverter @48Vdc & just one you can build with .
For NOW till all the Midnite inverters are released , Id pick OUTBACK with a mate  @ 120Vac 60hz


Now this one is what many might think ,1500 watts is good for a fridge & lights  BUT your maxed till you add in a genset to piggy back .=https://www.solar-electric.com/outback-gfx1548-grid-interactive-1500w-48v-60hz.html

This is what I would do : https://www.solar-electric.com/outback-power-vfxr3648a-hybrid-inverter.html
48Vdc , Mate  to program in your setup , grid tie (for resell later & costs only 45 bucks more, Ya didn't limit the resale ) More than enough power if you have sun & thats when work gets done . Sleep mode that's not as good as the SS300 , but the SS300 is 12Vdc only (Very limiting ) and since you moved up to 48Vdc your harvest is much better .

I'll add as Im needed to cook now

VT

Updated my pick
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 09, 2018, 10:10:40 AM
Any ideas when the Midnite inverters will be released? It would be nice to have the CC and inverter the same brand. Future integration and additional items added to the system would be easier to integrate and monitor.
Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on January 09, 2018, 12:30:01 PM
Quote from: UpNorthMan on January 09, 2018, 10:10:40 AM
Any ideas when the Midnite inverters will be released? It would be nice to have the CC and inverter the same brand. Future integration and additional items added to the system would be easier to integrate and monitor.

It is probably going to be awhile on the inverters  - they have not even sent out any beta test units yet far as I know.  There usually are lots of bugs to work out so best to wait until they are on the market for awhile too - unless you can put up with incongruities.  If you are ready to get things up and running now better stick with the tried and true.

There is another long thread about the inverters on the forum .

Larry

Larry
Title: Re: Layout of a new 800w system
Post by: Ron Swanson on January 09, 2018, 03:34:50 PM
Quote from: ClassicCrazy on January 09, 2018, 12:30:01 PMThere is another long thread about the inverters on the forum .

Can you point us to it or remember what the title is?

The time is ripe for a new inverter to come to market since the competition has gone all corporate bureaucratic and won't listen to us any more.  The owners' most recent former company is getting worse by the day it seems.
Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on January 09, 2018, 07:25:13 PM
Quote from: Ron Swanson on January 09, 2018, 03:34:50 PM
Quote from: ClassicCrazy on January 09, 2018, 12:30:01 PMThere is another long thread about the inverters on the forum .

Can you point us to it or remember what the title is?

The time is ripe for a new inverter to come to market since the competition has gone all corporate bureaucratic and won't listen to us any more.  The owners' most recent former company is getting worse by the day it seems.

here is one http://midniteftp.com/forum/index.php?topic=602.0
here is another  http://midniteftp.com/forum/index.php?topic=3770.0

Larry
Title: Re: Layout of a new 800w system
Post by: Vic on January 11, 2018, 07:44:56 PM
Quote from: UpNorthMan on January 01, 2018, 06:42:44 PM
   ...    I am looking at purchasing a 1500W Aims PS inverter because of my fridge

...Any thoughts?
Ed

Hi Ed,

There have been a number of folks,   who have been disappointed with AIMS  inverters.
Am not trying to bad-mouth products,  but  just look at the Tare (idle) power figures for the exact inverter that you are considering.

Also pay close attention to the maximum battery voltage limits for any inverter or inverter/charger that you are looking at,   particularly if you plan to use Flooded (FLA) batteries.  Cool/cold FLAs usually need high charge voltages in Absorb and EQ.

AIMS has concentrated on the low-cost end of the market,  generally,   and   there often are important things lost,  when companies focus too much on cost.

At 1500 (real) Pure Sine output power,  you are really beyond the capabilities of reasonably rational 12 V systems  (as you probably know).

FWIW,   opinions,   Vic
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 12, 2018, 08:18:32 PM
Thanks for all your input! I won't need one for a few months, May, June time frame. Maybe by then, some will be released. I would volunteer to be a beta tester if needed , but I not really qualified. I am doing my research and looking for the right stuff. I don't like the China stuff. I work in manufacturing and see that quality isn't usually the highest item on the list. I wasn't aware when I first posted the Aims inverter the origin of manufacturing. My load won't be very large 95+ % of the time. I will have a few larger loads for short periods. My wife wants a small microwave, a vacuum, and power tools for me from time to time. Any construction would be done with a generator. This brings me to 2000 watts, 1500 minimum. Most power consumption will be led lights, a radio and small fridge.

I have settled on a 48v battery system. I do have time, I'll keep planning the rest of my project. When the time comes, I will have to cross that bridge. Hopefully Midnite will be starting production!

Ed
Title: Re: Layout of a new 800w system
Post by: Westbranch on January 12, 2018, 08:38:24 PM
Ed, don't be swayed too easily on the fridge front, by the word INVERTER.  Most of the inverter types so far are in the highest features/biggest size fridges /most costly range....  there a lot of the freezer on top models that use less power and are running at 1/3 of the price...  We got an on-the-floor-model from Sears rated at < 1 Kwh / day with low startup load ~30A, running 7A or less... You will have to search the tables published yearly by your Gov and ours. 2018 version should be out now.

have fun there are a lot in the lists.
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 12, 2018, 09:36:02 PM
For now my power usage will be low for the cabin. As time goes on, our needs and knowledge will grow also. So a adaptable system is a must. Or plan some components oversized. That can work, but that can easily rack up extra$ spent and then if something breaks, its more expensive to fix. With modular equipment, a person can add to, if demand grows. Or we should have bought part "B" instead of "A"

I like the USA stuff higher quality, more durable, better support, and from my research, best warranties.

48v stuff seams to be less available. Quite a lot less choices.

I checked out the MidNite inverter links mentioned above. Sounds like there is still a little R&D going on. Looks like more Great products coming.
I will wait patiently like the rest.

Ed
Title: Re: Layout of a new 800w system
Post by: CDN-VT on January 17, 2018, 11:19:51 PM
Quote from: Westbranch on January 12, 2018, 08:38:24 PM
Ed, don't be swayed too easily on the fridge front, by the word INVERTER.  Most of the inverter types so far are in the highest features/biggest size fridges /most costly range....  there a lot of the freezer on top models that use less power and are running at 1/3 of the price...  We got an on-the-floor-model from Sears rated at < 1 Kwh / day with low startup load ~30A, running 7A or less... You will have to search the tables published yearly by your Gov and ours. 2018 version should be out now.

have fun there are a lot in the lists.
On Westbranchs  info I do Agree 90 %  BUT !!
I run 8 freezers here  & a few that double in to a fridge , all chest  type & NO electronics on them , just the old up to 2001 style and older .
No I live in power winks (storms etc) and outages , like if your 1500 watt inverter see you pull the switch on the drill , wife turns on the microwave & the freezer want s to fire up on it's demand . Too many of those will kill a  TIMED-X (programmed in ) fail on the electronics . Hence why all my stuff is click & clunk & NO electronics  here.

Neighbour farm is Angus beef , 6units 25CF freezers , he losses one a year , with extended warranty he has them replaced but that's from first purchased date.  I know this cuz I store his beef till a replacement arrives . Were Grid tied ..
JFI


& ed , your not looking at the right places for the 48Vdc stuff , Thats the best & the least the companys make because of one sale . 12Vdc is the bottom & everybody wants to sell & then upsell .

Its out there , I have it & im in the USSCAN  with the worst customs of any country beside the Philippians..

VT
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 19, 2018, 05:57:43 PM
I realize that 2000w would be a absolute min size. With the potential of high power surges and demand, I would have to carefully watch my usage. The VFXR3648A that was suggested does look to be the front runner at this point. Schneider and Magnum also seem compatible. The concern right now is the high voltage limit for charging. If I show up to the cabin in the dead of winter at -30F and for some reason the panels weren't charging the batteries correctly, or my batteries are low. I need an inverter/charger that can also handle 8.5+ volts above a standard charge voltage to compensate for the low temp. (If my math is correct for a 48v system,Trojan batteries) I plan on having a small heater in a very insulated battery box to keep the batteries a decent temp. If the temp gets to low, the battery capacity will drop to far. A 3600W inverter will handle what I need. I realize charging will also warm the batteries, but I don't want to have to worry to much about the batteries. If all else fails, I can have a neighbor/friend grab the generator and fire it up for a few hours to save them. I have a small fridge with a freezer that is rated for .8amps. Just a few cubic feet, we aren't overly concerned about the fridge at this point. As time goes on and we expand our usage, I have allowed room for expansion.

My first thought on the whole system was to make it just big enough to get it going for a few years and expand as needed. Minimal startup cost. But, as probably most, I've learned that somethings you don't go to cheap on. The knowledge and advice on this forum has been very helpful!!!! ;D ;D ;D

Back to the inverter, is there a option on the VFXR3648A to set a max draw from the battery? lets say 2500w? I'm looking at max battery draw, not the max charge amps. Max charging amps is a settable parameter. I don't know if I'll need it, but I may.

I'm also hoping the the salt batteries are back into production when I pull the trigger on the inverter and batteries. I am only being optimistic, it's easier! With the old price and spec's, I couldn't afford  the 5+ batteries at one time. I thought I read about 14.5a max draw per 48V battery. Like I said, my cup is half full!! I'm not saying what's in it though. ;D ;D ;D

Are there any other suggestions for inverter/charger. 120v, 60 cycles, single phase, pure sine, low temp comp for charging, 48v solar system, 3-4 k watt input.

Thanks
Ed




Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on January 19, 2018, 06:32:40 PM
If you look at specs you will see that Gel type batteries have pretty decent performance in very cold temperatures.
These are a type of gel called lead crystal
I haven't seen a lot of feed back on them - hopefully they live up to their claims
http://soneil.com/advance-technology-battery/performance/

Larry
Title: Re: Layout of a new 800w system
Post by: Westbranch on January 19, 2018, 08:05:40 PM
Ed, what are the temps you are using for your  winter LOW? range? duration?
I have a standalone charger with Temp correction now and it will be my backup once I finish building...
I did not come upon a max minimum temp listed for any of the ones I looked at.
What you may find is you will not get as many amps in the available chargers as you want... and be careful of Industrial FORKLIFT chargers , that do not use the BULK, ABSORB, FLOAT pattern
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 19, 2018, 10:47:39 PM
Table 16 page 65 of the operators manual states
" DC OUTPUT RANGE (Charging) 42 to 68 Vdc"
Bulk charge per Trojan is 59.28 @77F
-/+.0028V per deg per cell from 77F
At 0F it would be .0028*24*77 = 5.1744 volts (comp per cell * number of cells * temp difference)
59.28+5.1744 =64.4544volts @0F
It could easily be colder for long duration's ,often in the dead of winter it can stay below zero for a high.

A lot of the cheaper inverter/chargers don't state that they won't reach this high of voltage.
Just something that I hope I won't need, but for the price of a larger one, I think it's worth looking at.

Ed
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 20, 2018, 08:17:59 AM
I have looked at other inverter /charger systems. The Victron Energy system also looked attractive. From what I've read, it doesn't meet the output requirements of 120 v 60hz. Some of the other higher rated ones fall short in the 48v range. I'm not trying to put any manufacturers products down. Manufacturers have a sweet spot or target user for their product. But reality is that I need a reliable system that can handle some extreme cold temperatures. This system is for a cabin, not a home so if there is a problem and I'm not able to address it. One of my contacts can just fire up a portable generator for a few hours to bring up the battery's SOC until I can address the malfunction. I live 3.5 hours away. I am planning on having some sort of monitoring system that can send basic system information. This is something that I will have to look at later. I only have cell service, so there is another set of parameters. I'll cross that bridge later also.

As far as temperature, the cabin is 25 miles NW of Tower MN. This is one of coldest spots in the state. We aren't located in the valley like they are, but it still gets darn cold.
http://www.fox21online.com/2017/02/02/coldest-place-small-minnesota-town-earned-states-frigid-title/ (http://www.fox21online.com/2017/02/02/coldest-place-small-minnesota-town-earned-states-frigid-title/)

I looked at the crystal battery. It does at first glance look appealing. I'll do more research on it. I am looking at a 225ahr @48v system. I am truly looking for a battery bank that can be kept in the cabin. Safer, warmer, shorter cable runs. With fla, I would have to build a insulated battery box under the cabin. My cabin is built on piers, so there is room, just more to build and mouse/ squirrel proof.


Thanks Ed
Title: Re: Layout of a new 800w system
Post by: CDN-VT on January 20, 2018, 09:52:00 PM
Tower MN = https://en.wikipedia.org/wiki/Tower,_Minnesota


Nice size Town Ed.

Bury the cells is what i was going to post , You are on rock or dirt ?
You might need to make a special cell box that's insulated and built like the new Styrofoam blocks that you pour  cement into , offers insulation & then You can double the insulation with :https://www.lowes.com/pd/Insulfoam-Common-0-5-in-x-4-ft-x-8-ft-Actual-0-5-in-x-4-ft-x-8-ft-R1-9-Faced-Polystyrene-Garage-Door-Foam-Board-Insulation/3033278

Then vent from the bottom of the box   small amounts in winter.
You will need VERY large cables to feed the Outback  So I would plan on using two drops of PVC from the cabin into the Cell box & feed small air from cabin to the cell box through the PVC & have one for POS & Another for NEG  . I have used Aluminum wire that we use for grid tie  that feeds the house. That with industrial fittings to transfer large amps on startup to feed the inverter . We use nylock grease on the wire & terminals . This way the voltage drop should be very little.

Next on the inverter . I picked VFXR3648 in the case it needs  field work ,
I bough Robins older Outbacks that needed a slight repair , I called outback tech repair & got them the send a board , swapped it & sent the old one back .
The Tech lady I dealt with sent instructions & spare seals & hardware.
Field serviceability is WHY i picked  Outback , till Midnite  comes outwith  theirs..
VT
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 24, 2018, 06:43:25 PM
Tower and the surrounding  Arrow Head region has a lot to offer in the way of recreation and adventure. The Soudan mine is a neat place to go and visit. I've been there a couple times with the family, 1/2 mile pretty much straight down. They also perform some science experiments down there. All can be seen with a tour. The whole area has a lot of mining and lumber history along with other outdoor recreation.

I am lucky, there is dirt under the cabin. A lot of places in that area have a lot of rocks. You have to dig as big around or bigger  compared to depth. So many large heavy rocks.

Burying it does make some sense, It would help with some of the temperature extremes. There is some grade under the cabin, 5' drop in 32', I might be able to use this to my advantage. You mentioned venting out the bottom, are you thinking like a 2" PVC pipe from the bottom and then out the side and up? Then my cable drop('s) come in from the bottom/side. And use a small pancake fan to apply positive pressure into the drop pipe. I've read that the +- cables should twist, or at minimum, run parallel to each other and tape together. Would this be recommended?

Right now, there aren't any walls up inside, so a piece of 3" conduit wouldn't be an issue to install. I'm not sure on the exact size required, that will be determined when wire sizing is done. Do you know if the drop pipe has to be steel conduit for code. A friend mention it need to be steel, not PVC.

I can design the box cover area for more ventilation for summer. I was thinking of something along the lines of adding heavily screened in wall extensions that would lift the roof up enough to get past the insulation.

I appreciate the inverter suggestion and I believe I understand the reasoning behind it.
Do you know if there is a setting on the VFXR3648A to limit inverter output wattage. Either on the Dc input or AC output. Not the through circuit. Depending on the battery type at startup I may need something smaller. I'm hoping for Aquion Energy batteries. But I won't be able to afford all that is needed right away. Due to old output specs, at least 5 would be needed, probably more. I haven't done enough research and they still aren't available.

Ed
Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on January 25, 2018, 12:19:59 AM
Twisting your cables if you can is good to cut down on RFI noise .
Last I heard Aquion went bankrupt but I just looked them up and see they came out of bankruptcy . When I looked at their battery specs a couple years ago - they were very large and heavy for the amount of energy they can provide. And I thought kind of expensive. Never did hear from anyone who has them how well they really perform in real world .

Do you have code up there you have to follow ? Or is it just best practice electrical installation you want to do ?  I don't really know all the ins and outs of code but I don't see what difference it would make using PVC conduit instead of metal - though I don't know where you ant to run this conduit.

As far as batteries staying cool - having space between them is good otherwise the inner cells will get warmer than the ones on perimeter.

You probably want to get enough batteries to run your inverter - and the associated surges from motor starts.

Larry
Title: Re: Layout of a new 800w system
Post by: Vic on January 25, 2018, 02:39:09 PM
Hi,  Ed,

Hope that you will carefully consider weather or not to use Aquion batteries,   even if they do return to the market,   AND  have good prospects of being/remaining a viable company.

You appear to be sensitive to some of the considerations of using them,   but,   they  have had poor surge current performance,   and a few other things that make them different from other batteries that are used for off-grid systems.

Have you had a conversation with former MidNite Solar Tech Support chief,  and later,  Sales Manager (or similar position):  and Forum SuperModerator, Halfcrazy (Ryan):?

He was an initial Beta Tester for Aquion,   testing the first version,   and later their improved batteries.  The Link below is for his MN Forum Profile:
http://midniteftp.com/forum/index.php?action=profile;u=2

Please send him a PM. He has decades of experience in the Solar Industry,   having been an Installer,    and a generous resource of information,   here,   and elsewhere.

Just FWIW,  Good Luck,   Vic
Title: Re: Layout of a new 800w system
Post by: Robin on January 25, 2018, 07:08:38 PM
I did not have time to read through all the threads, but Larry gave you some good info on Aquion batteries. I would say to avoid them. Too expensive for what they do. Unless your cabin is really large, they also take up a lot of room. The only real reason to buy them is if you want to keep lead and acid out of the environment, but since batteries are 99% recycled, that doesn't make much sense.
No inverter is going to limit power until you reach its maximum. They just don't work that way. It would tend to burn up loads. If your batteries are going to freeze, that is a big problem. You are on a limited budget, but have some interesting issues. It doesn't sound simple if foolproof is what you need.
Title: Re: Layout of a new 800w system
Post by: UpNorthMan on January 27, 2018, 10:04:57 AM
Thanks for the feedback!  Aquion batteries sound out unless the price goes down or performance goes up.

As far as code, NEC is what my main concern is. The township that the cabin is located in follows Minnesota building code. No local code.

As far as the inverter size, 3600w plus inefficiencies does sound like my batteries are to small. That has been a concern since conception. That is why 1500w - 2000w inverter was my initial size.

Is there a general rule of thumb for minimum battery size for inverter? battery amp hour/inverter wattage I thought I read somewhere C/8 for FLA batteries, about the same as the charging specs. Is that also the same for AGM?

Thanks Ed
Title: Re: Layout of a new 800w system
Post by: tecnodave on February 13, 2018, 12:33:37 AM
UpNorthMan,

Check into composting cocoa bean hulls for heat for your batteries! Us Alaskan's have been using 10 gallon milk cans filled with cocoa bean hulls for auxiliary heat. They compost at 155 degrees Fahrenheit and will scorch the galvanizing off the cans! A couple of cans in your battery box will bring the temperature up markedly!

On referigeration.....I'm using a knockoff of the Danfoss DC powered inverter compressors Referigerator. I have Grape Solar 5.0 cu.ft referigerator's that have Chinese "Coku" compressors.
These  units are native 12 or 24 volt DC input and have a specialized 3 phase inverter built into the compressor. That are very energy efficient as the compressor rapidly cycles on and off, sometimes compressing for only 5-10 seconds and off for 15 seconds. Sounds like the cycling would use more energy but it does not. These two referigerator's use far less power than one smaller AC powered Refrigerator.  By running my referigeration on DC I am able to use a much smaller inverter as it does not run any motor loads......no start surge to worry about. Max startup power is about 90 watts , run time is 46 watts even when the compressor is rapidly cycling.

Unfortunately Grape Solar has since exited the DC referigerator business but they are not the only player. The SunDanzer is probably the best of them using  the Danfoss DC powered compressor, but they are also not the only player. This technology is widely available in third world countries, but has been slow to be adopted here. Sharp makes very nice units but they are not yet available in the america's yet,widely used in south-east Asia to the phillipines.

As far as I know the Danfoss and Coku compressors are virtually identical. Danfoss is Scandnavian so would probably be better in quality than the Chinese Coku, but I have had no issues with the mechanical or electrical parts of the Grape solar units. I broke the freezer door hinges on my first unit and there is no fix so I am using a styrofoam plug in door to seal the freezing compartment. 

I have only  1kw solar for my motorhome cabin feeding a Classic 150 with 4 units Rolls-Surette L-16 batteries at 482 amp hours.(24 volt) Full time inverter is Exeltech  1100 watt , runs high end sound system and computer gear, big inverter is only used when nessecary....Magna-Sine MS4024AE 120/240 volt 4 kW. To run power tools and deep well pump, mig welder, etc.


I have tried to keep everything at battery voltage but that is not always practical. I have a Sony hi end auto stereo sound system that sounds like junk compared to my Carvers and Klipshorns.....but oh well! I put up with the Sony which will drive the Klipshorns but does not have that wonderful "Carver Sound" to save energy sometimes. Sacrifices need to be made sometimes.

David.
Title: Re: Layout of a new 800w system
Post by: ClassicCrazy on February 13, 2018, 11:43:10 AM
There is an Amish company that is making DC fridge/freezers using those efficient Danfoss compressors I think.  One of their models has two compressors so you can make either compartment into either fridge or freezer mix or  match .  Better call them for more info about which model is made by them because they were also  still selling some of the older DC freezer units that were made in China ( I think they bought out that company ?)

I met them at the Midwest Renewable Energy Fair and their work looked quality .  And no the Amish around here in Wisconsin do not use solar but the Amish in Indiana do - at least for their refrigeration needs.  So that is why they like using DC direct since they can put up simple systems and not use AC inverter ( don't tell them there is one in the compressor  -  ha ha ! )
http://www.thesolarfreeze.com/SolarFreezer.html

Larry