This is a fairly general question with no specific example in mind as I was just thinking about the problem, but was unable to find any answers on the internet (probably because I am not asking the right questions). I will however give a hypothetical example that may help to give clarity to my question.

Ok I am trying to understand how to combine 2 or more independent DC voltage sources, but will stick with 2 for now. Say these sources were 2 solar panels which have different power and voltage characteristics, one 22Vmp at 180W and the other 30Vmp at 240W, it wouldn't be advisable to put these in parallel or series and for the purposes of the question lets say this is not an option.

What would be a good way to combine these 2 DC sources into a common DC source?

up vote 5 down vote accepted

Boost or buck them all to the same voltage and then parallel them to a charge controller.

The nice thing about DC is that it's fairly forgiving to design interfaces between differing pieces. There are definitely exceptions, especially when converting between DC and AC, but for the most part it would be fairly trivial to regulate the output of any number of differing solar configurations to a common reference and let physics take over from there.

For that matter, this kind of design can essentially become a charge controller in and of itself. The poor man's way of doing it would be to regulate all power sources to battery voltage and just let it all float on the battery. This is far from optimal charging, but it works.

  • thanks for the answer, so I could just boost them all to say 40V using have a common node for all the boost outputs, where they combine and some bulk output capacitors. – Ant Mar 9 '15 at 13:32
  • Yes, if you match them fairly closely. For that matter it may be easier to make them both boost to 20 volts and put them in series. No matching that way. But you always have to be careful with current. – Sean Boddy Mar 9 '15 at 13:44
  • Thanks again and one last question, I want to do more research on this, I understand Buck and Boost circuits pretty well. But what area should I be researching as it was difficult to find examples and literature on this specific topic? – Ant Mar 9 '15 at 13:55
  • This is all about distributed generation and DC load sharing. – Sean Boddy Mar 9 '15 at 14:08
  • Sean thanks again I will research these 2 topics – Ant Mar 9 '15 at 14:13

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