New here from Texas and building a house, trying to pick the right solar design

[TXHomestead]

I’ve got a builder constructing a new 1900sf home for us on land we own in central TX. I’ve tried to incorporate as many solar friendly aspects as possible into the design and while I have grid power, I’d prefer to not have to rely fully upon it or mess with a grid tied system. We installed all LED lighting, and all heavy loads that can be are on propane. Everything but my air conditioning is 120v. The A/C system is split between a 2 ton central unit and a 1 ton ducted min-split, with the thought being I could run some of it off a battery short term or small generator if needed for more than a couple hours. Exterior walls are 6” and filled with spray foam, so the house is pretty efficient. They installed the service panel in the home but there’s room for a contoller/inverter next to the panel and I can wire to it easily.

ideally, I think 2 Mpp LV6548s, appropriate battery back up and around 10-12K of PV could probably power the whole house, with some load shedding and the grid recharging the batteries on low sun days. I can mount panels on roof and/or ground mount and my only concern is that the system might not pass muster with the insurance company if the house burns down. I know that is a hot topic (sorry bad pun) but I would appreciate any insights or better alternatives that won’t cost more than a swimming pool. Maybe someone has already done a similar system? If I left anything out, please let me know.

Thanks!

 

[Hedges]

Batteries cost more per kWh than buying from the grid, by the time they reach the end of their cycle life.
Therefore, I suggest a grid-backup system, with small battery kept charged by grid and PV producing all the power you need.
(Assuming decent net-metering plan is available.)

Some time in the future, batteries will cost less and grid power will cost more, then you can buy a big battery.

Inverters need to be able to deliver starting surge of any motor loads. Sufficient PV can run them all day.
You can pick among several that are UL listed.

My system uses Sunny Island and an AGM bank just large enough to last one night.

 

[TXHomestead]

Thanks! I don’t know what other utility companies providers rebate for power but mine is about 20% of retail cost. I’m wanting to place my meter near the power pole, 200 ft from my house , then run underground to my service entrance. I’m not sure if grid tied requires the meter to be in close proximity to the controller/inverter. Heck, Im not even sure if there is any wiring differences from the service panel to the meter With a grid to system. I can see the benefits of having the grid to dump surplus power and reducing battery capacity to just a standby back up level. That’s gotta be the best of both worlds.

Honestly, it is tough to devote enough focus to the solar install at this point, when this weeks dilemma is that they put the wrong facings on my wife’s kitchen cabinets! We’re blessed with plenty of sun and room to mount panels without restrictions, so evenutually, I think we’re going to have a nice system and low electric bills.

 

[Hedges]

Built the house first, but try to have roof vents located where they won't hit or shade future panels. Multiple orientations SE, S, SW, could be ideal.
Maybe have standoffs installed, lag screwed to joists. (If not installed until later, more likely to just hit sheathing.)
All assuming rooftop, not ground mount.

If you can do all DIY labor for the PV system, hardware runs about $1/watt. Over 10 years, $0.05/kWh. Over 20 years and replacing inverter once, $0.03/kWh. So if "net metering" gives 20% of retail as credit, power you bank and use later, 5 kW delivered to receive 1 kW back, you get power for $0.15/kWh. That is cheaper than all but the cheapest batteries.

Some utilities want separate meter for PV. Some install one meter which records production/consumption separately, and your PV just lands on your normal breaker panel. "120% rule" says you can have main breaker + backfed PV breaker no greater than 120% of panel busbar rating. For instance, SquareD QO 225A panel with 200A main can have 225A x 1.20 - 200A = 70A max PV breaker. 80% loading, 70A x 0.80 = 56A max continuous. 56A x 240V = 13.4kW of inverter. (other choice of panels would have lower rated busbar, reduce how much PV allowed.)

If you do battery backup, downstream of inverter you install a protected loads panel. I suggest putting an interlocked "Generator" breaker on main panel, so you can manually flip breakers to power anything in house.

Our net metering terms are changing for the worse in California. But, during grid failures my large PV & inverter runs A/C and everything else while gradually charging and floating batteries.