"Strange" Watt reading on MNGP

[Muskoka]

**Edit: Figured it out I think. That's a output to battery Watts reading. We had 25-30amps at 29.6volts absorb (battery manufacturer specs), so that would explain the 850ish watts and be in the ballpark. Against better judgement and advise, he bought these batteries way too early and they sat for months without charge. SG is low and their not taking anywhere near a full charge.**

Have a question guys. Just finished a solar install for a friend and were using a Classic 150.

Here are the panel specs.

10 Panels

270 W
7.66 IMP
35.2 VMP
8.28 ISC
44.4 VOC

They are wired in 5 series strings connected in Parallel in the Midnite combiner box. This is a total off grid system. He has a 24v battery bank, L16 batteries, 4 batteries in series, 420ah at 24v.

So, 2 panels in series, 70.4 Volts, times 7.66 IMP, should be 536 watts (per 2 panels in series). Multiply by the 5 strings should be around 2680 watts, plate rating would be 2700 watts. Just some simple math.

My question is in regards to the Watts display on the MNGP. I'll give an example. Yesterday the incoming voltage reading was anywhere between 75-80 volts depending on sun (temps just above freezing outside), and the current (amp) reading was anywhere between 25-30 amps, again depending on the sun. The watt reading was never over 850 watts on the display. This confuses me a bit. If there's 75 volts coming in, and the batteries are taking 30 amps of current, the display should say we are harvesting roughly 2250 watts. Why does it only show 850'ish watts on the display.

I'm obviously not understanding something here, please set me straight.

Glen

[zoneblue]

You got it. If they are flooded you better EQ them hard til the sg comes up. If AGM theyll be just fine.

[Muskoka]

"You can lead a horse to water..."

I've told him numerous times what "needs" to be done, it's getting it done that's a problem. He want's a "set it and forget system" and that's just about impossible with solar. These systems need "maintenance". They are flooded batteries.

All the cells yesterday had a SG around 1.170, and there's no sun for the next 5 or so days. He has a charger, but not near enough power to equalize. I told him to cross his fingers and hope for the best, almost $1600 in batteries are slowly dying. With some luck, and putting the boots to them when the sun comes back, the SG will hopefully come back. I'm not liking his chances though, 2 of the 4 batteries have pretty "dark" looking positive terminal lugs (almost black), not a good sign.

Glen