[trhway]

it isn't a car, so the range of technological options is much wider, ie. there is no need for high capacity small batteries. One can hydrolyze the water during low loads and store the resulting hydrogen (hydrolysis equipment and stationary storage is relatively simple and cheap). A generator with gas turbine to burn the hydrogen would cost on the scale like $400/kw - a small addition to the $2K/kw capital cost for solar panels install. The week of reserve storage - 200kwh to be generated - with even low 40% efficiency of turbine generation - would require storing 250m3 of hydrogen to provide a week reserve per 1kw of basic capacity. Lets say that storage is generous $1/m3.

As result, under $3K/kw we'd have a week of reserve and the ability to short-term double power during peaks using the gas turbines. And using the same loan calculations it is $0.075/kwh.