Use of diodes when connecting solar panels in parallel? Answered
I have a bunch of 24 volt 270 watt solar panels. Eventually I'll be putting three in series, then combining the strings in parallel, but for a temporary measure, I want to just connect two in parallel. I've been in tv repair for over 40 years so electrical theory doesn't confuse me, but solar systems are a different story. I've used four smaller panels to run a car radio display at an old car show swap meet for the last 12 years, and I just ran them in parallel, then into the charge controller. Now I'm reading about blocking diodes, and I understand what they're for and that some people use 'em and some don't.
My question is, physically, where do you stick them, and related to this, what is the purpose of using a combiner box? Is the box just to provide a weatherproof place to make the connections? Are they used to provide the place to stick the diodes? I see they have circuit breakers inside, and it appears there's one for each panel, or string of panels, but I don't see the point. If a panel can generate 10 amps, you'd want a breaker bigger than that so it doesn't trip at full output, but what could trip it then? You can't get more than 10 amps even if there is a short.
This should be common sense, but since I don't have a combiner box yet to look at, can I assume if it's made to combine four panels or strings of panels, you can connect just two or three and save the unused ones for adding on later?