OK, thanks.I calculated peak kW AC produced and average effective sun hours from an insolation calculator.

One-time capital cost (at today's prices) is $0.50/W for inverter and PV panels, $1/W including ground mounts, wiring, etc.

Amortized over 10 years it comes out to $0.05/kWh (if I remember correctly.)

Might have to replace an inverter at that point, and amortized over 20 years that brings it to $0.03 (rather than $0.025) per kWh.

Beyond 10 years time value of money increasingly important, so maybe $0.05/kWh first decade, $0.01/kWh second decade.

If you can keep system cost closer to $0.50/W than $1/W, that's a lot of savings.

My original install was more expensive and 17 years ago, so I amortize over that period and come up with about $0.20/kWh.

Since then I've bought more for upgrades and battery backup.

One can do more complicated math involving cost of capital, but with cash in the bank earning between 0.01% and 2% today, I leave interest rates out of the equation and just divide by operating time, cycles, kWh over a decade.

For batteries, I amortize over cycle life.

My AGM would cost $0.50/kWh if cycled enough to wear out. More expensive as I use them, which is standby waiting for a grid failure.

I apply similar math to Lithium. Commercial lithium batteries used to cost just as much per kWh as my AGM, higher capital cost for more cycles.

Today DIY lithium looks like it can be 1/2 the capital cost of AGM and several times the cycle life.

I didn't want to hijack Texas so I created a new thread.