I jumped in head first

[Shotgun]

I've got a background in electronics, so how hard can this solar stuff be. Right?

My goal wasn't to go off-grid, or get rich selling power back to Progress Energy. I live on the outskirts of the power grid, and I work from home. I wanted to trim my power bill, increase power reliability, and get some backup capacity.

After reading until I was thoroughly confused, I ran into the PowMr range of All-in-one charger/inverters. It'll charge the batteries using only PV, and then output from them till they run down. At which point, it will switch over to pulling from the grid. Since it never pushes to the grid, I don't have to ask permission or deal with inspections.

I got to work. I got the HF2430U60 from PowMr. I got six used 250W panels, and two 12V, 156Ah batteries from SanTan Solar. A distribution box with four breakers from the big box store completed the gear (I always keep wire, connectors and such on hand). Total cost, including shipping was under $1500. I mounted the controller and batteries in the closet of a spare bedroom that I use as an office. Drilled a hole through the wall to bring the power cords in. No, I didn't forget the drip loop

I pulled the office circuit from the main panel and ran that to the new distribution box, which is powered by charge controller's output. The breaker was then used to provide input to the controller. My panels are still on the ground, but I"m in the process of building a greenhouse on the southern side of my house, and they'll be the roof. That side of the house gets hot enough in the summer that you can feel the heat through the walls. The panels will be providing shade. I ran one other, rarely used circuit to the new distribution box, and I plan to add the living room and maybe the bonus room in the future. Each has small, but constantly used loads.

So far, the batteries, which are only charged by PV, keep all the loads running till about 2am. I'm thinking that is OK for now. I don't really have the PV configured for maximum energy collection. But, I would like to get a better handle on how much power the system is generating. The PowMr seems to indicate that I'm generating twice the current than what I'm really getting. I cant find software for the PowMr. Any suggestions?

 

[snoobler]

I've got a background in electronics, so how hard can this solar stuff be. Right?

My goal wasn't to go off-grid, or get rich selling power back to Progress Energy. I live on the outskirts of the power grid, and I work from home. I wanted to trim my power bill, increase power reliability, and get some backup capacity.

After reading until I was thoroughly confused, I ran into the PowMr range of All-in-one charger/inverters. It'll charge the batteries using only PV, and then output from them till they run down. At which point, it will switch over to pulling from the grid. Since it never pushes to the grid, I don't have to ask permission or deal with inspections.

Wisdom

I pulled the office circuit from the main panel and ran that to the new distribution box, which is powered by charge controller's output. The breaker was then used to provide input to the controller. My panels are still on the ground, but I"m in the process of building a greenhouse on the southern side of my house, and they'll be the roof.

I expect that should avoid NEC 2017 PV module shutdown requirements.

So far, the batteries, which are only charged by PV, keep all the loads running till about 2am. I'm thinking that is OK for now.

If you're actually depleting the batteries, and they are some variant of lead-acid, you are doing significant daily damage. If lead-acid, you never want to discharge below 50% routinely. An emergency would dictate otherwise.

I don't really have the PV configured for maximum energy collection. But, I would like to get a better handle on how much power the system is generating. The PowMr seems to indicate that I'm generating twice the current than what I'm really getting. I cant find software for the PowMr. Any suggestions?

Sorry, got nothing for you.

 

[Northernchateau]

I suggest you double check the voltage and amperage with a Digital Clamp Meter Multimeter.
.Check both the PV and battery and compare to the the unit numbers.
That might help you understand if the calibration is off or a software glitch.

 

[Shotgun]

I expect that should avoid NEC 2017 PV module shutdown requirements.

Once I get the panels up on their shelf, I'll have a "big red button" in a box with a fuse, because all power sources should have a cutoff.

If you're actually depleting the batteries, and they are some variant of lead-acid, you are doing significant daily damage. If lead-acid, you never want to discharge below 50% routinely. An emergency would dictate otherwise.

Good point. I modified the setting to switch to pulling power from the grid when the batteries drop to 24.2V, then not go back to batteries until they are charged back to 25.0V. I went with the L-A instead of lithium due to cost, and I'm expecting lithium costs to start dropping like a rock any day now. But, if I can get 3yrs out of 'em instead of 1.5, that is a good tradeoff.

 

[snoobler]

Once I get the panels up on their shelf, I'll have a "big red button" in a box with a fuse, because all power sources should have a cutoff.

True, but NEC 2017 requires that each rooftop mounted SOLAR PANEL have an automatic disconnect. There are devices for that, and they're about $50 each.

Good point. I modified the setting to switch to pulling power from the grid when the batteries drop to 24.2V, then not go back to batteries until they are charged back to 25.0V. I went with the L-A instead of lithium due to cost, and I'm expecting lithium costs to start dropping like a rock any day now. But, if I can get 3yrs out of 'em instead of 1.5, that is a good tradeoff.

24.2V under load is a pretty conservative LVD, so you're good there. Depending on current @ 24.2V, you might be terminating at 60-70%. Nothing wrong with lead. I have 8X T-1275 FLA in 4S2P for 48V. 12kWh tested and cost me only $500 (+ time). This is a "get me by" until I get my NMC/LMO bank online (I've been saying that for many months).

Lithium demand is only going to increase, and we're already in the asymptotic portion of the cost reduction curve. It's taking longer and longer to "halve" the $/kWh. In the last year, costs for cells obtained from the reputable sources identified on this forum have plateaued to slightly increased. The last "halving" took 4 years. The next halving is going to take 10 years.

Battery Pack Prices Cited Below $100/kWh for the First Time in 2020, While Market Average Sits at $137/kWh | BloombergNEF

BloombergNEF’s annual battery price survey finds prices fell 13% from 2019 Hong Kong and London, December 16, 2020 – Lithium-ion battery pack

about.bnef.com

 

[Shotgun]

I've got two Leoch XP12-540FR in series.
They advertise 155Ah. Is it correct to multiply that by 24V to get the Wh? That gives me 1.860kWh, which seems low.

But then some of the spec sheets say "15MIN-1.60 V / Cell (Watts): 539". 539W/cell x 6 cells/battery x 2 batteries => 6468W, which seems ridiculously high.

I'm missing something here.