solar dorkery: observations from the first morning on the new setup

Backyard chicken people love to sit and watch their birds do chickeny stuff; this is called “watching Chicken TV”. Solar dorks like myself watch Solar TV.

I’ve remarked before that overpaneled systems tend to not demonstrate amazing max output figures during charging since they reach Vabs much earlier than local solar noon. 50% of rated power is a max-charging number I’ve observed frequently for flat-mounted systems.

Let’s see how that generalization holds up. lHere are the stats for today’s observation:

  • 3.4:1 overpaneled system, 750w:220Ah
  • bank depleted overnight to about 40% DoD
  • local sunrise: 0652 (but there is a mountain in the way!)
  • local solar noon: 1310
  • local sunset: 1928

Although the sun rose at 6:52a it didn’t break the (very close-by) due-east range until ~8:30a. Until then the panels were pulling 20w from the light reflected by the atmosphere. Big jump happens when the sun peeks out from behind the mountains. Harvest increased until about 10am when Absorption voltage was reached and charging demands started dropping.

sorry, I’m terrible at this

Max harvest during charging was 403.64w, just before reaching Vabs. It’s a little over 53% rated, perhaps a tad high because the mountain blocked the sun until it was a little higher in the sky. With no obstructions to the east I’d guess I’d see Vabs by 0915 with a max harvest of ~350w (47% of rated) before current demand tapered.

The panels could probably yield 620w under normal conditions on a bigger controller, although my 40A controller would start clipping at ~580w (14.7v x 40A). 150v controllers in the 50A range are rare, most are 60A and are several hundred dollars. I’ll stick with the one I have and forfeit the 40w of unharvested power. I don’t have any microwaves, induction plates, or other big loads. If all my heaviest loads were running at once:

  • fridge’s compressor
  • crockpot on HI
  • evap cooler on max
  • maxxfan on max

it’d still be a little under 275w.