MPPT controller recommendations
I purchased four of these 100 watt panels from Home Depot. https://www.homedepot.com/p/Grape-Solar-100-Watt-Polycrystalline-Solar-Panel-for-RV-s-Boats-and-12-Volt-Systems-GS-Star-100W/204211365 I fi...
Forum Discussion
BFL13 wrote:
"One exception is portable panels with a long run, (100ft+) then series panels with MPPT will reduce IR loss"
Depends. You then have lower controller efficiency by going 24-12 instead of 12-12. If the efficiency difference is 3%, that counters a lot of wire loss.
good point. run power loss is related to current squared, so one needs to compute the I^2*R loss vs. controller efficiency loss. On reasonably short good wire size, parallel 12V panels likely win.
I did some data collecting a year or so ago looking at charging current series vs. parallel with a midnite solar Kid using 3 160W panels and 100Ft of 30A RV cable with ground paralleled with one side. At 100ft with my controller, series gave an advantage, 25A in parallel vs. 8A in series. But the advantage was less than 10% IIRC A few amps at most in charging current.
Now that 24V panels seem to be noticeably less expensive than 12V the quandry is.
should I go with PWM and spend the extra a MPPT controller would cost on extra 12V panels, Or should I go with 24V panels and MPPT. which ends up less expensive?
