Best panel setup for delta 2

I just ordered a delta 2 and i want to make the most of solar for off grid as far as panels. I also dont want to start a fire.

If i just order the ecoflow 100w panels, whats the optimal number? Just 5 in series? Is there a panel i can ship small quantities and get more bang for the buck?

The specs show the open circuit voltage (voc) to be 20.3v per panel for the 100w model. The Delta 2 has a maximum input voltage limit of 60v so only 2 panels could be wired in series for that unit. A third panel would give 60.9v. Also, the voc rating is for ambient temperatures around 70F (IIRC). In colder conditions the panels produce more energy and voltage. I plan on a temperature factor of about 1.12 for the panel voc around 32F. With that factor, the voc becomes 20.3v x 1.12 = 22.736v. Although the D2 can charge with 500w solar maximum, the maximum voltage limit cannot be exceeded because the overvoltage will fry the D2 unit.

i have a pair of D2 units and a pair of 220w bifacial panels. IIRC, the voc for a single panel is 21.8v and temperature corrected would be 24.416v at 32F. Two of these panels in series could therefore input 48.832v and 440w without harm to the D2. A third panel in series would fry the D2 because the voltage would be way beyond the 60v limit. As I understand it, if the wattage or amperage were in slight excess, that does not present the same problems as the excess would simply be wasted. Not so with the voc.

FWIW, I was able to pull 427w from 2 220w bifacial panels about a week before the Winter Solstice here in Michigan. That's pretty good. If you can fit fewer but higher wattage panels in your application, go that route instead of multiple 100w panels again paying attention to the voc limitation. Such a strategy will probably take up less space and be more efficient although perhaps a bit more unwieldy.

Here's a link to the Ecoholics webpage that discusses how to maximize solar charging for Ecoflow power packs:


Yes, my limited (and beginner) understanding is that series adds voltage and parallel adds amps so 2S2P with the 100w panels (200w, 40.6v ignoring the temperature factor, 11.8amp) should be OK since the D2 has a 500w, 60v and 15amp solar input maximum. But, you should consult the page linked above or an electrician (which I'm not) to be sure. My intent in posting was to warn you about the voc limitation perhaps in time for you not to purchase panels you couldn't use. 5 in series won't work but I think 4 in 2S2P will be OK. Perhaps someone more experienced will chime in and verify what I've related.