Useful Solar Data

BFL,

During the time and location for my chart the sun elevation would have changed from about 47 to 50 degrees elevation. And 50 degrees is the maximum elevation so that the curve is flatter during the time of the chart than earlier.

Also since the sun evelation reaches it's maximum at 12:00 and the ambient temperature was 65F it seems likey that this increase in in sun elevation was more of a factor in the slight increase in amp output vs panel temperature during the time of the chart. However, regardless I have no way to measure panel temmperature or actual radiation levels other that as I have noted it was a blue sky.

At any rate as a solar newbie I'm pleased with this output. My goal was 45A during the summer and perhaps I'll exceed that. My hope/planning was for the 3 flat mounted panels to be equivalent to 2 panels. Nothing would be better than to exceed my conservative estimates.

Good results in the 40s.

I am puzzled that the 1045 amps are not much different from the noon amps. The sun does get higher between 11 and 12 enough to make a difference in amps. You usually get your max amps at noon unless you are aiming the panel to follow the sun.

This is a different set of numbers entirely, but it shows how much amps change from 11 to 12 with a fixed panel pointing south. (Salvo's graph with my tracking line added)

OP - relax. Didn't read the whole 3 pages, but first 2 posters were spot on - relax, go out and have fun. Unless your energy use is way above the average, 750W is plenty, in those places. With any kind of controller. Examining the difference in performance btw MPPT and PWM under varying conditions won't help, in this case - it's too complicated to install that much solar all-parallel with PWM.

I've just come from the neighboring state - North Baja California. 490W flat 4 degrees solar with 30A MPPT.

On a dark day with no sun it collects 50-60 AH in February, this is more than I use in a day. The only bad time is when it rains - then it's running 1.0-1.5A, i.e. 1 AH per hour. But it simply doesn't rain in those places in winter. In 3 months there was probably 3 hours of rain total, and not too many cloudy days - I would say less than 20% of time.

On a good winter day it collects upwards of 70 AH - don't know the upper limit since I don't use that much in a day. From previously done research I recall that maximum that it would collect in this place and this time of year is ~90-100 AH.

The bottom line is - 490W flat in winter in this climate zone is filling my batts full, 99 days out of 100, and you have 750W.

You can see the effects of temperature when using mppt charge controller. Prior to a cloud output could be about 44A. After the cloud passes and the panel cools down the current increases to about 48A. That's about 10% drop in performance. pwm doesn't have that issue.

2oldman wrote:

CA Traveler wrote:

2oldman wrote:
The only thing I'd care about is the amp output at noon. You could be seeing up to 50a @ 13v. Wow.

Are these panels tilted?

no, only 4 degrees for water runoff.

OK. Then that'll likely cut your output to around 30a. I'd be interested in seeing that number.

Here is the 3/3/15 result, Phoenix area, 750W panels, flat 4 degrees west slope. Blue sky, white drifting clouds. Inverter load exceeding controller output.

CA Traveler wrote:
Clear day in the Phoenix area today. Batteries 100% SOC so loaded them with 100A and recorded 36A output from the controller at 1pm.

3 serial flat mounted 250W poly panels. So I believe I'm on track for 45A+ this summer. Does this seem reasonable?

BTW at the 36A output the MS MPPT 60 adjusted the panels to 5.16A and 86.4V with a controller efficiency of 97%. The panels in series are rated at Imp 8.18 and Vmp 91.74.

750w with PWM should get you 750/130 x 8.2a = 47.3a with panels aimed at high sun. The difference between flat and aimed at high noon is all over the map (literally) In May at 49.3N I got 7.2 flat instead of 8.2 aimed.

So you should get, in May at 49.3N, 47.3 x 7.2/8.2 = 41.5a at high noon.( a bit more with MPPT) Anyplace else, anytime else, could be anything.

Clear day in the Phoenix area today. Batteries 100% SOC so loaded them with 100A and recorded 36A output from the controller at 1pm.

3 serial flat mounted 250W poly panels. So I believe I'm on track for 45A+ this summer. Does this seem reasonable?

BTW at the 36A output the MS MPPT 60 adjusted the panels to 5.16A and 86.4V with a controller efficiency of 97%. The panels in series are rated at Imp 8.18 and Vmp 91.74.

I think your lacking in the panel power for those 4 little batteries. LOL

assuming you arrive with a fully charged battery bank
and set the trimetric to zero
you can track your solar yeild via the controller and watch the deficit balance
to add or subtract.. and track your power use

i have my watt meter between the solar controller and the the batteries
so i read what the solar injects into the system

for about a yr, i also had one mounted on the input to the TWO inverters, so i measured all inverter use ( 12v lighting was minimal draw ) the residential lighting, the fridge, PC and TV, are the big power use

that gave me real good data on power used against power produced
almost always a deficit, hence the use of the generator every morning,

that way each night starts out as near full charge as can be, and the large bank, gives me some overhead for those days that turn inconvienent for any genset use