When speccing solar panels, overkill is good.

I just now thought of something that should have gone into the post below.

There’s been a sea change in the way people spec solar panels since I first got involved with the issue. They used to be basically the most expensive part of the installation, so people put a lot of effort and skull sweat into carefully determining their total wattage requirements and then buying the minimum possible number/size of solar panels to make it hopefully work. Then they tried to squeeze the highest possible amount of performance from that probably-inadequate panel array with things like sun-tracking racks and seasonal angle adjustment, neither of which turn out to be very practical in real life.

Then the Chinese pulled the rug out from under domestic panel production by undercutting the price to what seemed at first an absurd degree. The price fell to a dollar a watt or even less – my new ones are far less, but I don’t really know how much of a neighbor discount I got – and it became possible to solve your wattage problems by just building a big array on a solid mount and calling it good.

Speccing the size of the array is more about how long it takes to charge your batteries than about squeaking by on minimums – and in my particular case, since my biggest mount was using old scrounged panels, making sure that my panel capacity always substantially exceeded my actual charging needs worked a benefit because those big panels were never 100% and sooner or later were bound to deteriorate. And I did not know at the time that replacing them wasn’t going to be a big deal. I could be running a substantially bigger battery bank than I do but that always seemed unwise, both for budgetary reasons – batteries are expendable and must periodically be replaced – and because more charging capacity than you need always turns out sooner or later to be a better policy than just enough.

So I’m just saying – as a general rule, don’t try to squeak by on minimal solar panel capacity. It can obviously be taken too far, so don’t go nuts but in general more is better. If nothing else, even in the desert the sun doesn’t always shine on cue.