Finally turned on

[JMT]

It's been almost 2 years since I ordered the first two panels and set up a small proof of concept with a single 12v AGM battery.
Another ten panels, 7.3kWh LiFePO4 battery bank, 24v inverter, and a transfer switch later, it's finally powering my home office.
(Note that this system is not intended to power the whole house and is not even tied into the house wiring except for earth ground.)

It still needs some tweaks: a couple of in-line fuses, the batteries should be wrapped, the panels need to be grounded, and I need to do some more pruning (you can see the shadow near the right-side of the panels). Other than that I'm happy with everything so far, and managed to do it without electrocuting myself.

Specs:
12x 100-watt Richsolar panels (the last 4 were a different size than the first 8): https://www.amazon.com/gp/product/B07DW8YNMF/ ($90ea, $1080 total)
A PV combiner box (6-parallel, 2-series) https://www.amazon.com/gp/product/B01N96GJFT/ ($166)
60A MPPT (40A probably would've been sufficient - Amazon doesn't sell this particular one anymore) ($100)
8x 285Ah grade A cells https://www.alibaba.com/product-detail/Grade-A-105Ah-200Ah-280Ah-3_62448638595.html ($82ea during a promotion, $874 w/ shipping)
Daly 200A 24V BMS https://www.aliexpress.com/item/32891427621.html ($173 w/ shipping)
3000W 24V inverter https://www.amazon.com/gp/product/B01M5L0A5L/ ($389)
Automatic transfer switch https://www.amazon.com/gp/product/B07F12RDZ2/ ($119)
Wires, mounting hardware, lumber, screws, etc. (about $750)
OVERALL TOTAL: $3,651 (not counting the "proof of concept" components that aren't in the final build)



Given the low consumption my house uses already, it could theoretically pay for itself in 6-10 years.

Anyway, I'd like to give a big shout out to Will for the great Youtube videos that helped me with this, and all of the other useful info I've found on these forums.

Thanks all!

 

[Boondock Saint]

OM MY . . . your cells aren't compressed and they're going to bloat and explode! Your panels aren't optimally facing the sun, and your BMS is off-center by about 3 degrees to the right. I dunno how you're going to survive this.

JK, I'm impressed and glad to hear your system is up and working, congrats on the success!

Cheers

 

[OnTheRoadAgain]

It's been almost 2 years since I ordered the first two panels and set up a small proof of concept with a single 12v AGM battery.
Another ten panels, 7.3kWh LiFePO4 battery bank, 24v inverter, and a transfer switch later, it's finally powering my home office.
(Note that this system is not intended to power the whole house and is not even tied into the house wiring except for earth ground.)

It still needs some tweaks: a couple of in-line fuses, the batteries should be wrapped, the panels need to be grounded, and I need to do some more pruning (you can see the shadow near the right-side of the panels). Other than that I'm happy with everything so far, and managed to do it without electrocuting myself.

Specs:
12x 100-watt Richsolar panels (the last 4 were a different size than the first 8): https://www.amazon.com/gp/product/B07DW8YNMF/ ($90ea, $1080 total)
A PV combiner box (6-parallel, 2-series) https://www.amazon.com/gp/product/B01N96GJFT/ ($166)
60A MPPT (40A probably would've been sufficient - Amazon doesn't sell this particular one anymore) ($100)
8x 285Ah grade A cells https://www.alibaba.com/product-detail/Grade-A-105Ah-200Ah-280Ah-3_62448638595.html ($82ea during a promotion, $874 w/ shipping)
Daly 200A 24V BMS https://www.aliexpress.com/item/32891427621.html ($173 w/ shipping)
3000W 24V inverter https://www.amazon.com/gp/product/B01M5L0A5L/ ($389)
Automatic transfer switch https://www.amazon.com/gp/product/B07F12RDZ2/ ($119)
Wires, mounting hardware, lumber, screws, etc. (about $750)
OVERALL TOTAL: $3,651 (not counting the "proof of concept" components that aren't in the final build)

View attachment 47325View attachment 47326

Given the low consumption my house uses already, it could theoretically pay for itself in 6-10 years.

Anyway, I'd like to give a big shout out to Will for the great Youtube videos that helped me with this, and all of the other useful info I've found on these forums.

Thanks all!

Lookin good!

I've told my wife about cutting down on the electric bill which is outrageous every month here, using solar.
I'm not sure I could have got her onboard otherwise. She didn't really care....until I equated a reduced electric bill with it.

 

[Boondock Saint]

....until I equated a reduced electric bill with it.

Mama always need shoe money. Clever in your appeal.

 

[chrisski]

Very nice. What is in the home office powered by solar? Also, any DC loads?

 

[JMT]

OM MY . . . your cells aren't compressed and they're going to bloat and explode! Your panels aren't optimally facing the sun, and your BMS is off-center by about 3 degrees to the right. I dunno how you're going to survive this.

JK, I'm impressed and glad to hear your system is up and working, congrats on the success!

Cheers

lol. Originally I had the BMS located higher, but the darn leads were too short to reach the battery. If I had realized that sooner I would've mounted the back board lower. The cells were the last components I placed because I didn't want to drop anything on them.

Unfortunately my house faces west and doesn't have a side of the roof that faces south. The panels truly face south in that array and are even angled around 35 degrees (which is supposedly ideal for my latitude). I just hope that lets them get enough sun.

 

[JMT]

Very nice. What is in the home office powered by solar? Also, any DC loads?

My work computer (with 3 monitors), home server, gaming computer, a couple of 3-d printers, regular printer, network components, plus whatever gadgets I'm tinkering with at the time. Best guess is a constant minimum load of 200-300W. Over the course of a day that's 4800-7200Wh. According to my power bill, I have an average daily use of 20kWh for the whole house, so the office is probably at least a third of that.

The power's all going to a couple of new outlets I installed in the office (through the two yellow cables running out of the transfer switch). There aren't any direct DC loads coming from the system (though in reality everything in the office converts AC to DC, a couple of times for the computers which each have a UPS also, so probably quite a bit of inefficiency there, but also redundancy...)

 

[chrisski]

My work computer (with 3 monitors), home server, gaming computer, a couple of 3-d printers, regular printer, network components, plus whatever gadgets I'm tinkering with at the time. Best guess is a constant minimum load of 200-300W. Over the course of a day that's 4800-7200Wh. According to my power bill, I have an average daily use of 20kWh for the whole house, so the office is probably at least a third of that.

The power's all going to a couple of new outlets I installed in the office (through the two yellow cables running out of the transfer switch). There aren't any direct DC loads coming from the system (though in reality everything in the office converts AC to DC, a couple of times for the computers which each have a UPS also, so probably quite a bit of inefficiency there, but also redundancy...)

I've kicked around doing something similar, with adding a couple of outlets to a room. Most of my energy bill comes from the air conditioner, and with two AC units, that's 80% of the bill for six months a year. The solar output from a few panels would not even touch my summer energy needs. So for me, that would be a fun project and not a cost savings. The grid where I'm at is flawless, and were that to change, I'd really consider building a couple outlets in a room.

I think direct DC into the house, although nice to have, is often not worth the efforts for the little bit of efficiencies you gain back. I spent so much time and money installing four DC charging ports in my trailer to save a 1 amp per hour parasitic draw. Then again, might be easier to wire a room in a house for DC than I think. The RV I did the install was quite difficult to add 12 volt lines without tearing up walls. I've come to learn that anything I wire for 12 volts is low powers and will not put a dent in my overall output. Wires just get too thick and arcing a real risk for DC.

Supposedly, with POE (Power over Ethernet cables) some things electricians would normally install, like low wattage lights can be done by tech guys. I've never seen lights, but I've seen security cams.

I recently saw a tiny house frame on a trailer for sale, and to me that is a blank slate. I would like to one of these trailer frames and make a solar build out of it.

 

[JMT]

Update after 1 week...

I've been troubleshooting issues with getting the batteries charged up.
The ATS switches correctly. By default, it'll switch to house power at 22V and back to batteries at 27V.
On the evening of the second day, the batteries only charged up to 26.8V, and wouldn't go higher, despite the fact that there was still about 20A at 33V flowing from the panels.
I set the ATS to a 23V cutoff and 26.5V turn on so I could enjoy the system anyway without risking the batteries dropping too low.
And after a bit of research, it looked like my charge controller wants 36V for charging a 24V battery.
So I switched the 12 panels from 2S 6P (~40V 30A) to 4S 3P (~80V 15A).

But with a couple of cloudy and rainy days this week (and the fact I hadn't pruned the tree yet), the batteries never had a chance to charge up.
And it seems the inverter or BMS was doing something strange, because the BMS has tripped a couple of times now with the batteries just slightly under 23V.
I'm guessing the ghost drain of the inverter might be bringing it just below 23V, which is making the inverter cause the BMS to trip.
The big problem is that when the BMS trips, the cells don't charge anymore, since the BMS sits between the cells and charge controller, so they just sit there at 23V until I notice. That design is good for preventing overcharging, but if the batteries are too low (and 23V shouldn't be that low, right?), then it never recovers without help, and if I don't notice right away that can be a full day of sun that gets wasted.

As of today the tree is finally pruned, so I should get 2-3 more hours of full sun on the panels.
I also switched the ATS to use 24V and 27V, assuming the extra sun will charge the batteries high enough, and hopefully nothing trips the BMS.

More sun, higher voltage, higher cutoff... I hope that takes care of the issues.

If anyone has other ideas, please let me know. Thanks!