Three weeks ago I installed the new MPPT charge controller that Big Brother sent me, and while I can’t say it had a revolutionary effect on my electrical power, I will definitely say that it had a much bigger effect than I expected it to. Like, I should have looked at the change years ago.
Case in point: at 10 ayem this morning…
This…
And this…
…do not go together. Yeah – batteries fully charged and in Float at ten o’clock on a moderately cloudy morning. That’s not even supposed to happen. This was the sort of morning when I would normally question the wisdom of firing up the kitchen oven for bread baking – but this time the question barely entered my mind. I don’t see any particular difference on bright sunny days but any time conditions are less than ideal the difference is striking.
Now: My original plan was to wire the older solar panels up on the Lair’s roof to the new controller but Neighbor S, who knows more about these things than I do, reminded me why that’s a bad idea. That would be equivalent to putting two different ratings of solar panels on the same rack, something you’re not supposed to do because the larger panels will overwhelm the smaller ones and basically make it as though the smaller ones aren’t even doing anything for reasons I don’t really follow. Anyway, I had forgotten that you’re not supposed to do that. So – since the price of MPPT controllers has come way down without me noticing and since I have something resembling an income now without such nuisances as rent and regular utility bills, I’m going to get a second one as soon as practical.
You can mix solar panels if you put them in series. If you have, say, 100W panels with 16V, and 250W panels at 26V, put them in series to get 42V (as long as the charger is rated for that voltage). If you have 3 of each panel, then make 3 identical strings and put them in parallel.
It gets trickier if you have dozens of panels and a multitude of types, but you just have to make sure that a) each string adds up to the same voltage, and b) you don’t exceed the input voltage rating of the charger.
The diodes in the panels that prevent back currents when bits and pieces are shadowed will prevent any strange internal swirls and confused electrons.
All that said, identical panels with their own dedicated charger is a nice way to go too.
I’m glad that this new tech is working out for you.