[stevehull]

Memphis,

I really like your concept of being off grid with solar PV as primary and simply using the grid as a backup (like when a dark cloud goes overhead). Most people do the opposite - use the grid as primary and have PV panels (or wind turbine, generator, etc) as backup.

Think about your comment regarding a dark cloud going overhead. On a hot, humid summer day (what other kind are there in the south!), the PV output drops and the much needed AC output falls to zero - unhappy spouse and family.

But, allow the grid to seamlessly kick in for a bit and all is well . . .

This is exactly what Enphase has with their new AC batteries. The problem is - how long will the "dark cloud" persist. Perhaps nighttime is just an extended "dark cloud". That determines how many of their batteries you need - and they are expensive!

If you can put up with a dark cloud passing overhead, and are willing to suck off the grid for a bit, then what is the difference with the extended dark cloud such as night hours? Isn't it really the same?

I just put in a 10 kW Enphase grid tied system for my cousin (no Enphase battery back up), 40 265 watt panels and 40 M250 inverters. To meet peak demand (summer AC in July & August), he would need about 40 kW, but then much of that would be wasted in other months as the utility takes it and only compensates him for about 1/2 value. So we compromised and figured out just how much would supply most of the power, most of the year.

The next five years will see battery storage decrease in price, much like the exponential cost decreases seen with PV/inverters in the last five years. But for now, I am content to minimize my grid connection. First through conservation, secondly with energy efficient appliances (geothermal heat pumps) and thirdly with electrical generation itself. That triad is a stable three legged stool.

You have done much the same.

The grid connect allows a seamless, instantaneous flow between your generation and what you consumption need requires at very low cost. You might just have to grit your teeth and do it. Right now, it is by far, the cheapest, most reliable and available method to do what you want.

You just have to think of night time as an extended dark cloud . . . . until battery $/kWhr gets a lot cheaper.

Steve