I think there’s some major overthinking going on for less that 300W of power haha
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I think there’s some major overthinking going on for less that 300W of power haha
I am planning to fit a solar panel on my 78 roof .
the idea is to put 2x 100 W panels , slim and flexible style .
hook it up to a Victron 75/15 controller , to feed 2 Yellow Optima 75 ah batteries .
the batteries are quite old , but they still do the job .
batteries are in parallel .
my question is :
is it better to put the SP in series or in Parallel ?
pro -con for each .
which has better performance in shading ?
thanks Renago
^^ Fisher, there are indeed strong benefits to the series configuration as discussed earlier in the thread but as to your post #30 above it doesn't quite work like what you refer to, AFAIK. If you look at the IV curves for a solar cell, you'll see that as the insolation decreases, the current decreases significantly over most of the load range, but that the max power voltage doesn't. Even at low insolation the panels will still give fairly high voltage, but of course then only low current. And of course, with a good MPPT you will stay right at max power voltage. For example, just a couple of days ago, I was checking a nominal 20W panel, the sky was completely socked in and the panel was only putting out 2W, but the voltage was still plenty high, and the charger happily chugging along -if maybe a bit frustrated for not stretching its legs-. So your concern is not really that much of an issue in real life, I think.
Interesting, will look into that. My concern with the Victrons is they can’t be mounted under the hood due to their water rating being abysmal. That makes wiring a PITA. My charge controller (Epever Tracer that came with the Bugout) is IP68 rated.I would use two Victron controllers, one for each panel, and create a "Smart Network" for charging when using fixed and portable panels.
Not based on any real world experience or issue, I just read that it’s a potential pitfall for MPPT controllers to be aware of. I’ll probably follow the KISS principle and wire them in parallel. Thanks for your feedback!50W should be plenty to keep the battery topped off from just sitting there if there is nothing abnormal going on. A good controller would also make a monthly boost unnecessary I think. You could use a waterproof box but it's probably easier to just draw some wires into the cabin and keep a non waterproof controller there.
If the panels are to be in series, you can manually interrupt the circuit and introduce or remove one easily enough with switches or connectors, I would not bother with relays. If in parallel, I think 2 different controllers won't have any issue, they will just see whatever the battery voltage is at that time and react according to their own logic.
What is your concern about the 5V? Normally it's not much of an issue in practice if you have a panel that is built for a 12V system.