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diy solar

Adding solar panels of a different wattage

StevieRuss

New Member
Joined
Jun 9, 2022
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Hi guys. This is my first post and I don't doubt that this question has been asked many times before so I apologise for not finding any related threads so far.

I fitted out our camper with leisure batteries and a piddly little 100watt flexible panel some years back (to an EPever MPPT and 2 x 120ah AGM batteries). The panel only provides 40 watts peak now (it's broken somehow) and was too small for the job anyways.

The question is, I think I have enough room for 2 x ECO-Worthy 170watt panels and just enough at the front for a 120watt version of the same. I know that it's pointless to series these to a MPPT but can I put them in parallel? The VOC and panel voltage are quoted as identical so I think I can but i've never put any panel in parallel before so I didn't want to make any mistakes here and to obviously get the full current available from these panels. These are the quote specs from the manufacturer. Thanks in advance..

  • Related power: 120W
  • Open circuit voltage (Voc): 21.6 V
  • Maximum voltage (Vmp): 18 V
  • Short circuit current: 7.72A
  • Maximum current: 6.67A
  • Output tolerance: ± 3%
  • Temperate coefficient of Isc: (010 +/- 0.01)% / ℃
  • Temperate coefficient of Voc: - (0.38 +/- 0.01)% / ℃
  • Temperature range: -40℃~ +85℃

  • Rated Power: 170W
  • Maximum/Peak Voltage(Vmp): 18V
  • Open Circuit Voltage(Voc): 21.6V
  • Short circuit current: 9.89A
  • Maximum current: 9.44A
  • Temperate coefficient of Isc: (010+/-0.01)%/℃
  • Temperate coefficient of Voc: -(0.38+/-0.01)%/℃
  • Temperature range: -40℃~ +85℃
  • Frame: Aluminum alloy frame
 
You can parallel these panels because they have the same voltages.

You only need to add blocking diodes to the panels when paralleling to avoid that sunny panels feed another panel that is shaded. Search YouTube with “blocking diodes solar “ to see how it’s done.
 
You can parallel these panels because they have the same voltages.

You only need to add blocking diodes to the panels when paralleling to avoid that sunny panels feed another panel that is shaded. Search YouTube with “blocking diodes solar “ to see how it’s done.
Many thanks.

Do panels not already come with diodes? Good point though and i'll put them on my list..
 
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