Solar Panel Pair To Match - Precisely Or Just Nearly?

Martinf

Senior Member
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T6 Guru
I have a fully NDS Leisure system, with an NDS 110W solar panel. I want to add a second panel to provide more solar capture for a longer period over the year. The current panel has been superseded by one with slightly different characteristics. My original van converter, who would likely undertake the work, proposes that the existing panel should be removed so a precisely matching pair can be installed. This seems a waste and may also damage the roof.

So, must the solar panels be absolutely identical, or is a nearly the same modern equivalent good enough for a second panel? I acknowledge that adding a slightly different panel may lead to small loss in the aggregated input, but are these 'small' and with no other downsides?

I believe the current panel to be an NDS Solar Flex 110W Flex Module:
  • Max. Power: 110W
  • Voltage at maximum power:. 18,56V
  • Open circuit voltage: 21,6V
  • Current at max power ISC:. 6,32A
The modern equivalent appears to be an NDS 110W SolarFlex Evo Solar Panel:
  • Max. Power: 110W
  • Voltage at maximum power:. 17,28V
  • Open circuit voltage: 20,97V
  • Current at max power ISC:. 6,2A
Are these sufficiently similar? It is planned to bring them in as parallel feeds to an NDS Sun 300W Dual MPPT Regulator from which I can also take off a Vehicle battery feed (I have previously posted about challenges with maintaining Vehicle battery charge when camping). The main Leisure feed would go in to my existing NDS Power Service Gold controller.

Do I need two new panels or just a nearly matching additional panel, either option brought in through an NDS Sun 300W Dual MPPT Regulator.

Thanks, Martin
 
If you had two identical panels in parallel, then they would output different voltages/currents if they were in different amounts of shade, and no-one worries about that. The specs you have quoted are virtually identical anyway, so I would go with 1 new one.

Pete
 
@Pete C many thanks, I hadn’t thought of it like that! The simple observations are sometimes the best.
 
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