> When you say the rated output is 70watts per panel, is that monthly, dayly?

Been awhile since I checked, but IIRC they're rated in W/h. 40 panels @ 70W apiece = 2.8kW/h peak. Makes sense since most people use them to pump power back into the grid, and the power consumed from the grid is usually measured in kW/h.

> I thing it's a great investment, but down here, the most we see is solar-heated
> water tanks for the shower, and also, only in reeeally sunny cities in the
> country.

Agreed. When I was living in Southern California, I was in a top-floor apartment that faced East and had no crawlspace between the ceiling and roof. The DWP where I was billed its customers on a bi-monthly basis, so in the summer it wasn't unusual to have a $500-$600 electric bill because I had to run the A/C all day (pets).

I went to the management company with a proposal to install solar panels on the roof: the idea was that all tenants' and common areas power would receive an equal share of the panels' output. What I didn't tell them was that the real benefit would be to the people on the top floor, whose electric bills would be slashed dramatically just by the shade they'd provide to the roof. Not that it mattered; they weren't interested anyway.

Frined of mine with a place out in the Mojave Desert (near 29 Palms) has solar panels & storage batteries on his property out there. Works well for him, but then it's literally 800 sq. ft. and only used on weekends.