This 2.5kw starter system stared in my mind as a "what if" 2 days into power loss from hurrican Irma and I was enjoying the little Harbor Freight 100watt system I threw together at the last minute to get us thru that storm. So this is my first venture into DIY solar and I wanted it to be safe so I spent the extra money to get all components that were certified UL 1741. Although it was not inspected for code I believe it to be very close to code requirements.
Basic System was purchased from Webo Solar who I believe gave me a very fair price on all the components.
- 9 REC TwinPeak 2 Poly 285w modules connected 3S 3P (2,565 watts / 95.7 vmp / 89.1 charging amps)
- WEEBs for the racking system and 10 awg solar wire
- MidNite Solar MNPV3 Combiner Box
- MidNite Solar Classic 150 Charge Controller
- MidNite Solar E-Panel. Which is the Electric service panel for the whole system and made install and connection to the Inverter a snap
- Conext SW 4024 Inverter and Control panel
- All appropriate size breakers for the electrical
- 4 Trojan L16H-AC 435ah batteries in series 24v (purchased from a local battery supplier so I did not have to pay freight)
All other components like racking system, and electrical supplies came form local vendors like Home Depot, Lowes and Electrical Supply companies.
(NOTE 2019 Update: If I did it again I would NOT use UniStrut for racking due to possible rust issues and difficulty finding adequate panel mounts. I would instead have used all aluminum ProSolar Racking (https://www.solaris-shop.com/brands/ProSolar.html?page=3&sort=featured). Cost would have been about the same)
So far after a month the system has exceed my expectations powering most of my home's daily needs including well pump, fridge, lights, fans, propane gas stove starters, internet, tvs and computers ... all while never discharging past 35%. I know the battery bank at 435ah is too small, but even at this size it will give me 1+ days of full no sun autonomy with power management.
We have been running the system 24 / 7 since Oct 16 (I will now turn the fridge back to line side and run it on grid as it seems to be the biggest daily draw at 2.7 Kw hours per day. I want to try to make the batteries last as long as possible and doing so will only discharge the batteries about 20% each day)
The install went like this ... A big truck full with a pallet of Panels showed up at my house about 10 days after I placed my order for the REC TwinPeak 2 panels from Webo Solar.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6191;image)
Lagged the Unistrut Supports like this
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6193;image)
The Unistrut Looked like this
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6195;image)
And it went up like this
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6197;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6199;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6201;image)
Into a MidNite Solar Combiner box just under the Array thru the Soffit in the Attic via 10 awg Solar wire
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6203;image)
This all ran down to the garage in conduit with #8 awg THHN to the E-Panel and the Midnight Solar Classic 150
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6209;image)
The Midnite Solar E-Panel made for a very straight forward load panel connection to the Inverter. #8 was used to connect the PV to the CC and #4 was used to connect the CC to the battery breakers for charging. 4/0 then ran to the batteries from the inverter thru a 250 amp DC breaker. AC in to the inverter and AC out from the inverter was run wiht #8-3 NMB with ground.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6205;image)
And it all came out pretty clean
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6207;image)
Happy Stash of Brand New Trojan L16H-AC 435ah batteries
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6211;image)
So I closed up the Wall and Built a Nice battery box outside the shop in a carport using 10' 4/0 battery cable to get the batteries and gassing effect away from the system
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6221;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6223;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6225;image)
Locked the box And secured it with a Wireless Alarm Sensor Door Contactor Connected to my monitored alarm system
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6227;image)
I was happy so Far .... The system was performing as Expected... Except ...
Well Except it became very apparent I was not Fully utilizing the potential of the Array.
What to do? What to do? I was dumping excess power in the Sand every day.
So More research ...
and I came up with the idea of a dump load using the Midnite solar Aux 1 Waste Not feature. I connected an AC 120v 40amp SSR controlled by the low volt signal of the Classic 150s Aux 1 port ... and presto, with my water heater, now split into 2 parts: 240v upper element connected to grid ... the lower element running at 120v now only draws 1140 watts. Perfect dump load. The element is a bit too large unless I have full sun, so I am changing it out to be 750watts tomorrow. And I am still tweaking the settings in Aux 1 of the Classic 50, but it working as expected, taking my daily power generation with full sun from 4.5Kw previously with out dump diversion to now 10.2 Kw per day on a good day. Perfect. Wast Not Want Not.
Here is the Discussion (http://midniteftp.com/forum/index.php?topic=3881.0)that lead to the Final Conclusion of the AC Load SSR
Crydom D1240 DC control / AC Load SSR is mounted on a Heat Sink with thermal paste. It is connected to the L1 side of the inverter ... which has more than enough extra power to power the 1140watt load as the inverter was way over sized for my load and needs. Although I am dropping the element size to 750 watts to get better performance and dump on less than perfect days. With 1140 watts, if the sun is not out fully the Aux 1 turns the element on and off every 15 seconds because there is just not enough power to charge batteries and power an element that large. Eventually I may get a larger array.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6229;image)
Mounted inside the extra space of the E-Panel ... and doing its job flawlessly.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6231;image)
So now excess power problem solved. Just need to do some tweaking, Change from teh 1140w to 750w and the system should be pretty much dialed in. Been very happy with the end results. Thanks for all the help you folks on this forum have given me.
As an extra layer of control, I installed this Reliance Controls 306 CRK (http://reliancecontrols.com/ProductDetail.aspx?306CRK) 6 circuit generator transfer switch.
(NOTE 2019: This has since been upgraded to the 10 circuit modle. I now use both the 6 and 10 circuit units).
Using it as a Solar / AC line transfer switch, the 306 CRK lets me switch out up to 6 connected circuits from solar to Line load electric depending on my conservation. All from inside the house in the closet where the main load panel is located.
I then took the Generator Connector and back fed it into my main load panel, and using a generator safety switch, now I can power off of Solar / AC Line / Or Generator, which ever is available. My inverter charger can also be powered with either AC line or generator so I can charge the batteries with or without sun and with or without AC Line Power if the grid goes down.
I ran #8-3 NMB with Ground between my Inverter's L1 and L2 and the 306CRK breaker busbar replacing the smaller wire that was on the bus bar from Reliance. So rather than a Generator Transfer switch, the 306CRK functions as a Solar transfer switch.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6233;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6235;image)
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6237;image)
Looks great, congrats.
Makes mine look like a dog dinner, lol.
thanks for all the photos and documentation - it will be a good resource for others.
Larry
Quote from: ClassicCrazy on November 18, 2017, 02:34:47 AM
thanks for all the photos and documentation - it will be a good resource for others.
Larry
That was my hope. That it will help others make decisions about setting up a system. My one regret is not having gone 48v. I would have done it had I realized (actually had I thought it thru more carefully) ... that at 48v, you only need 1/2 the amp hours of batteries than at 24v.
In my thinking, I thought to get 435ah (or a bit more which is what i would have wanted), I need 4 at 6v for a 24v system and 8 at 6v for a 48v system. I could not afford 8. but I could have afforded 8 batteries of a lower amp hour rating.
Doing it again ... it would be 48v.
You may want to trim some of those trees back that are shading a bit of the panels.
Quote from: russ_drinkwater on January 04, 2018, 03:51:45 PM
You may want to trim some of those trees back that are shading a bit of the panels.
I assuming you mean this pic
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6197;image)
And this pic
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6201;image)
I have thought about it. But for now the array is in full sun by 9:30am. And it will be better as the days get longer. I think the cost would by kinda steep as I do not want to drop the trees responsible, and the offensive tops are pretty tall and wide.
The Strings are set up top to bottom, So as the sun comes up the 3 panels (edited: I wrote 2 here and this caused confusion. Just caught this error) on the far side are on and in full sun first as the sun starts to rise and shade moves across the array.
The panels are also manufactured so that if the bottom half is shaded, the top half still works. The whole panel does not die out. So I am getting pretty good early power as the shade starts to dissipate.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6311;image)
And they are wired internally like this, to even further enhance production during partial shading.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6313;image)
Matrix, I am having matching the description with your Sig Line and the pic...
Sig Line ...REC TwinPeak 2 285W 3S-3P 2565w
Description...The Strings are set up top to bottom.
I saw the Pallet of 9 Panels,and I see the 9 panels on the rack, BUT I am at a loss to figure out how you get the wiring easily made into 3S x 3p and with the panel orientation how you estimate that you are getting pretty good early power as the shade starts to dissipate.
My understanding is that you would have to reorient your PV by 90 degrees to match their diagram..
I am with Russ on the shade problem.
Quote from: Westbranch on January 04, 2018, 07:58:14 PM
Matrix, I am having matching the description with your Sig Line and the pic...
Sig Line ...REC TwinPeak 2 285W 3S-3P 2565w
Description...The Strings are set up top to bottom.
I saw the Pallet of 9 Panels,and I see the 9 panels on the rack, BUT I am at a loss to figure out how you get the wiring easily made into 3S x 3p and with the panel orientation how you estimate that you are getting pretty good early power as the shade starts to dissipate.
My understanding is that you would have to reorient your PV by 90 degrees to match their diagram..
Perhaps I am wrong. I have 3 panels wired in series. I have 3 of those series groups. And each of those 3 series groups wired in parallel. My understanding about batteries is (I know not the same as panels) ... if you have 6 batteries and wire 3 in series and 3 in series and wire those 2 series packs together in parallel, it is stated as 3s/2p. Help me clear this up if I am not seeing correctly.
My array is wired like this (except the diagram is rotated 90* from how my array is on the roof) ... I thought this was 3s/3p.
(http://midniteftp.com/forum/index.php?action=dlattach;topic=3907.0;attach=6315;image)
In the last 2 pics I posted above those are not my wiring, those are the manufactures shading and internal panel wiring. The first REC pic I posted is of a manufacture diagram showing their panels and shade effects, and the second REC pic is a manufacture diagram showing how REC wired 1 panel.
But you may be correct. To take full advantage of the panel design, a 90* rotation might actual work better given how the shade moves. But the shading I get from that tree most of the year is more of a 45* effect, it is not a perfect left to right (west to east). It actually starts un-shading in the upper left corner and runs down to the lower right corner.
Quote
I am with Russ on the shade problem.
I agree with the shade idea also, but it is not in the budget right now. And here at 9:50am on Jan 5 (close to the shortest day of the year) with about a 30% upper hi mixed light cloud cover, I am generating 1800 watts from the array (the STC of my array is 2565 Watts / The NMOT is closer to 1950 Watts.) and I have already generated 1.1 kWh's this morning.
So shading is a problem .... but it is not killing me.
I was a bit ho hum about a small amount of shading myself.
But even a shadow from a satilite internet dish was causing enough issues for me to move it.
Approx 200 watts in a 2000 watt array.
Just saying. And on over cast days it all adds up mate.
I will check me some shadows ;D 8)
I know some people have written me about the system I set up. I think it has its strengths and weaknesses.
I started out in mid Sept 2017 knowing absolutely nothing about solar and battery storage. I just knew I did not want grid tie, because I wanted to be up during an extended outage (think hurricane season). So there is hope for the uninitiated.
I did a month of research before purchasing anything, and I did not find all the threads on various forums discouraging an off grid set up if grid power is available until November ... and after the system was up and running. Those discussion probably would not have discouraged me as I was building the system as a hobby and for energy independence and not "green" or to save the planet or to save power.
If I could start all over again, with what I have learned, I would do it again. But things I would do differently:
1. I would have gone 48v
- It would have saved me about $300-$400 on batteries because I could have gotten 8 GC 230 Ah batteries for less than my L16s
- I knew the math (duh) ... I just did not think of it because I was so fixed in my head for getting the biggest L16s I could find
- And I could not afford 8 of them
- Also smaller battery cables and probably more efficient and less overall heat
- And now I am considering a mini split AC for daytime use ... You see where this is going.
2. I would have research inverters a little more. But for the money, the SW is a good little unit (looking forward to what MN rolls out for when I have to replace the battery bank and move up to 48v)
3. I would have bought ProSolar roof rack rather than "UniStrut" rack rails and hardward
- it proved cumbersome to find suitable end clamps for unistrut (I ended up using ProSolar clamps with the Unistrut that worked OK)
- AND ... the Unistrut at 10' left me only about 1" on either end for end clamps ... almost too short with my 3 panel wide array
- And now I cannot add more panels unless I go underneath with another 2 rack rails. No problem, but ProSolar would have cost very little more and would come in 16' lengths so I could have added yet a 4th string.
4. I would have built in some kind of code legal Rapid Shut down system.
- This seems to be something that is not talked about much in the forums and videos
- I had no idea about it when I installed
- I am working on plans and ideas to go back and install a Rapid Shutdown system now.
5. I would have bought a 6 string combiner rather than a 3 string (and probably would have integrated rapid shutdown)
Not much more I would have changed.
The system has been preforming very well. The dump load is now tuned and timed to work well with available light, fully charged batteries and excess power. And the REC Panels have proven to perform well in even partial sun and cloudy conditions. On most days I am producing 1000 watts by 9am even before the sun gets over the shad tree and is fully on the array. By 11am I am producing all the power the system is demanding up to the limits of the array. I have seen days were I produced 12.6 kWhs for the day. Here is a glimpse of May so far (the .2 day was testing, the system was off all but 1 hr and the 3.7 day was rain and clouds all day.)
My April power bill was the lowest in my records for the past 13.5 years. I cut my usage over half from last April 2017. This year in April I used 532 kWh's from the gird or about $48 in energy. (there was grid connect, taxes and other fees). Not bad for 2200 a sq ft house with two 3 ton central AC units (although in fairness the one unit hardly ever comes on bc we are not in that part of the house much anymore)
System has been up and running since Oct 15, 2017. 2.6kW Array, Grid-Interactive Conext SW 4024 Inverter running not connected to the grid the first 9 months and connect grid interactively (CSW AC Support Mode) the past 3 months. This is NOT a grid-tied system in any way and does NOT sell back to the PoCo. The system was designed as a 4000 solar generator to do 2 things:
1. Provide power to home essentials such as lights, fans, fridge, well pump, washer, etc in the event of a power outage
2. Offset the monthly power bill enough to purchase new batteries every 3-5 years with the PoCo savings
So far in the past year (thru Oct 15, 2018) the system produced 2.25 Megawatts which equals about a $300 savings on our annual power bill. I expect more in the 2nd year, the first 3 months I was generating only about 60% of my current monthly average. The 4 Trojan L16 batteries that where purchased costs $1,275. So my annual power bill savings are on track to pay for new batteries in 4.25 years. Should be about right if I can keep from destroying the first set. So far so good.
System over the past year has performed as well or better than expected. Powers my entire home except for AC and Cloths dryer. Will power all my needs for about 15 hours plus and would power much longer in a power outage if used moderation turning off the fridge for a few hours from midnite to 8am each day. (fridge is the largest load at 2500 Wh's per day).
Thanks for all the help over the past year.
MegaWatt Hours, that's a bunch different than just MegaWatts instantaneous.
Last year I ran 1500 miles...Last year I ran 1500 MPH
Fridge @ 2500kWh per day needs refined also...that is about 5 months equivalent to your stated PoCo bill alone...
Matrix, I have standalone as well as grid tie myself.
We have a switch in the house so we change from standalone to grid in a blink.
Gives us more control and allows for proper charging of batteries on cloudy (not seen for 6 months) days.
This arrangement runs 2 fridges and 2 freezers and all personal device charges, vacuum cleaner etc 95% of the time.
It is 24 volt. Onlt limit is the overload battery to inverter switch that drops out at 100amps draw.