Hello and new to solar

[Dustyjeansranch]

Hello and thank you all for a lot of information. I have been lurking for some time and learning. Watched a few videos too.

I inherited a system that had been partially installed by mc solar in Florida. They never finished the job before closing. Had to remove everything to sell the house since the permit had expired and was classified as unpermitted work. System is a 13.505 KW DC roof mount solar pv system with:
37 Aptos Solar DNA-120-MF26 365W pv modules
37 Enphase IQ7 Plus72-2-US 290W microinverters with rapid shutdown down
225 Amp main panel
Enphase combiner box
Everest K2 rails with various splice, connectors, foot, clamps, etc.

Our main house has a leased system through Sun-Run that I am unable to get out of the lease. It is severely undersized and is under the new solar 3.0. It is a 18KW system that costs $199.00 a month. Even with that we had electric bills a little over $900 a month last year. I have that down to $200 a month now. This is mostly from the Acessory dwelling unit (in-laws house) and my carpentry shop, various fans and lighting in the stables and the two well pumps. I would like to build a off grid system to power the ranch, wells, and shop.

I know the enphase microinverters will not work with off grid so plan on selling those and getting a 6kW inverter with a 48 volt battery bank. Most of the power needed is from dusk to dawn. I hope to reuse the panels, rails, hardware, wiring. Would like to have 240V split phase but can make due with 115v single phase. On the internet I find conflicting information so have not started this project but need to. What would be a good choice to use with what we have already?

Specs for panels are
VMP 33.96V
IMP 10.75A
VOC 40.7V
ISC 11.36A
Temp coeff. VOC -0.29%/C

Again thanks for the wealth of information.

 

[Osmethne]

Some thoughts.

At a voc of 40.7 per panel you'll need an inverter with at least 3 solar inputs. A lot of these 6kw inverters only have 2.

You shouldn't have much trouble getting 240v split phase with this amount of power.

I use an NHX-10k. That or something similar should give you everything you need.

You might be able to use the micro inverters but you would have to feed the ac output into the Gen input. There's an argument for keeping those if you wanted to pass inspection since they have rapid shutoff built in. But if you can get away with no having rapid shutoff then sell them.

You'll need to work out how many kwh of batteries you need. But the good news is that you can grow that number as necessary.

 

[Daddy Tanuki]

you can always go separate SCC like victron, or morningstar and not worry about the units inputs... just saying. If they are good enough for commercial remote cell towers... they are probably good enough for your house... just saying.

 

[Dustyjeansranch]

Some thoughts.

At a voc of 40.7 per panel you'll need an inverter with at least 3 solar inputs. A lot of these 6kw inverters only have 2.

You shouldn't have much trouble getting 240v split phase with this amount of power.

I use an NHX-10k. That or something similar should give you everything you need.

You might be able to use the micro inverters but you would have to feed the ac output into the Gen input. There's an argument for keeping those if you wanted to pass inspection since they have rapid shutoff built in. But if you can get away with no having rapid shutoff then sell them.

You'll need to work out how many kwh of batteries you need. But the good news is that you can grow that number as necessary.

Thank you for the response. I will not need the rapid shutdown. This system will be completely offgrid. We just got an estimate to get grid power to the in-laws house, a little over 18 grand.

I agree that 3 PV inputs are needed for the amount of power. I downloaded the manual to the NHX 10K and am reading it. I am curious why two of the 6,000 or 12,000 watt inverters would not work as well. That would be 4 PV inputs.

We are currently using an enclosed trailer that has 16 - 12 volt 100 AH batteries mounted on it. These are wired in groups of 4 for 12v 400 AH. They pull it to the main house every morning and charge the batteries. At night they pull it back and run the house off 2 - 3000 watt inverters. My wood shop is next to that house and the barn.

For now the second irrigation well pump is being powered by two predator 5,000 watt generator for 10 hours every other day. Not ideal at all but it works, most of the time. This pump we may use a Victron quattro inverter and have it's own PV.

Even with the 8KwH system we still have monthly power bills around $1500. Just trying to get that lower. Most of the power is for the main irrigation well pump. Summer the bills go up a little more.

 

[Osmethne]

Two inverters would work, theoretically. Lots of people have done it but I also hear stories of grief. It has the downside of taking up more space and also doubling the idle power draw.

 

[Kornbread]

You may be able to keep the micro-inverters and ac couple to an aio, or sell them and recoup some cost, otherwise, it looks like you can reuse most of that stuff. If you want a 6kw inverter, I'd get a 10kw inverter. Not that much difference in price and loads tend to upsize more than downsize. Would also give some headroom for lra surge of pumps/hvac.