Hi

Re: Hi

Thanks guys.

That site is showing me 115 Kw for the month of Sept or 3.8 Kw per day.
Annual total 1,414 Kw.

Looks like I am presently well down.

Re: Hi

RCinFLA wrote: »

Looks like you figured out what the nrel site number mean. They are equivalent hours of full sun (1000 watts/m^2) per day. They take into account statistical average of weather. For example where I live in S. Fla. June numbers are lower then May numbers even though the sun is higher in the sky due to more statistical clouds/rain amount in month of June.

Also good to see effects of panel tilt angle versus month of year.

Yes at Lattitude 28 (Plant City Fl) I shall be setting my tilts for 28 Spring/Fall, 43 Winter. zero Summer (early) and 5 late summer to squeeze every watt for my AC.

Also because of AC usage I suspect it would be better next summer to move 15 degrees West os South ( 195 degrees) for maximum afternoon power.

My only obvious (to me) screw up so far is choosing car batteries to save money; Auto Craft made by Johnson Controls. I contacted their Tech Support for 4 level charging volts/times and got pure BS values as an answer.

Re: Hi

BB. wrote: »

You probably found that pv Watts only goes down to 1 kW array size (minimum array). So, you have to play with the numbers.

Next, what are you using for derating factor? Typically, 0.52 derating (yes 1/2 of rated panel numbers) is a good starting point for off-grid systems for the "average" power available day to day/month/year.

And, note that your daily generation will only roll up AH/kWH into your battery bank until it is near 100% full... At that point, the charge controller "turns off" (or cranks back on output voltage) and it will stop totalizing power.

So, the daily charging figures may be limited by your daily load figures (light load days will log less power from the charge controller).

-Bill

Hi Bill. In summer at least I just swap AC from shore/generator power to inverter so no problem with cranking back.

Regarding derating factor it seems that the value 0f 72% I read in a thread here somwhere here seems to fit my situation but I may be misunderstanding? if 52% is correct then it is disppointing, I was calculating like this;

Average Tampa insolation 5.8 hours, my max theoretical PV output 680 watts, max seen PV output (in 3 days) 490 watts = 72% max and therefore expected average 490 x 5.8 per day = 2,840 watts per day. Am I over ambitious?

I just checked and see a 570 watt max for today even though it rained all day and total was only 1Kw so I see numbers on a day to day basis mean very little !!!