peak hours

[miike012]

I am looking for information on temperature coef. for Power. In my report I would like to talk about how it is calculated, and why buying a system with a low coef. will be most beneficial ( I need to back this with data) in hot climates..I live in arizona.

Can anyone guide me to any reading materials? I have been searching on google but no luck


Is this a good website to start off with

http://photovoltaics.sandia.gov/docs/PDF/IEDFB5~1.pdf

[Naptown]

Ok I went to the website you posted and the questions that I have are.. "PV System Specifications" I dont know what to put under DC Rating, DC to AC Derate factor, and how do I determine the angle for the array tilt and array azimuth entries?

The product I am thinking of purchasing is http://us.sunpowercorp.com/homes/pro...ar-panels/e20/

Standard derate on that program is 77%
You can tweak it depending on how you design the system.
Anyway top number is what the power tolerance on the module is Generally a +/- number if the manufacturer says it is -3-=5% use the -3 or enter .97 if -0 +3% use 1
If your inverter is rated for efficiency use that number.
If you are using microinverters set module mismatch to the highest allowable number
DC and AC losses unless you want to calculate voltage drop for each segment leave alone except if you are using microinverters then set DC to highest allowable figure.
Leave other items as default.

[epsgunner]

That explains the low efficiency.

True I guess.. but the extra 300 clam$ in my pocket makes me feel better..

Glad I went with 5 panels.. though by next spring and a JOB I may double the number and go 24v..

I'll be in south TX with lots of pure sun going on.. so the 725 watts (rated) isn't a bad start..

I can't get a good test here in NJ this week as we've got rain forcast everyday..

Do you think a GOOD battery would give me possibly more accurate numbers??

The battery I am using (car battery) has a BLACKEND positive terminal.. so I'm pretty sure its shot..

Usually by the next day (of testing) its back to 12.1V from the 13.9 or higher I leave it at..

ETA:

Just using the MS String Calc..

The irony is the MS TS45 MPPT is rated for a max of 600 Watts at 12v.. so the max would be 4 panels and 580 watts.. going PWM makes it 5 panels listed and 40.X amps..

I could squeeze one more panel and be at 48amps.. the PWM version has a overlimit upto 50 amps..

I'd have to get the TS60 MPPT to run my 5th panel..

[Sunking]

I'm unsure then I guess.

I have the Morningstar TS-45 PWM, and not the MPPT version..

That explains the low efficiency.

[epsgunner]

For DC Rating (where it has 4.0) change to be your total PANEL SETUP..

Example. I have 5 panels at 145 watts.. = 725..

Since the field is KW.. it would be: .725

What size panel(s) are you getting?? that page doens't say size..

Found 327W rating on the PDF.. how many panels?? 1, 2, 5,???

For the proper TILT angle we would need you latitude or zip code.. (got it 33.38)

Then 33.38 * .76 + 3.1 = angle.. 28.48

The Azimuth is usually DIRECTLY SOUTH (aka 180 is correct for most) unless you can't mount your panels facing directly south..

[miike012]

Try using PV Watts http://mapserve3.nrel.gov/PVWatts_Viewer/index.html

We all know this program.

Ok I went to the website you posted and the questions that I have are.. "PV System Specifications" I dont know what to put under DC Rating, DC to AC Derate factor, and how do I determine the angle for the array tilt and array azimuth entries?

The product I am thinking of purchasing is http://us.sunpowercorp.com/homes/pro...ar-panels/e20/

[epsgunner]

I hear you..

My HF meter AMP Section died after 1 use.. climbs up by itself.. even after trying to reset with touching the leads..

Latest numbers.. 14.4V 6.7A 95W PWM 99%..



New Numbers.. 14.4V 7.0A 101W PWM 99%..

[billvon]

on the main battery screen I now get 12.9 V on the battery (and going up) and like 1.9 amps and 25 watts . . . .

One thing I would strongly recommend - if you are doing efficiency measurements, get a GOOD volt/amp meter and use the same meter to make all four measurements (Vpanel, Ipanel, Vbatt, Ibatt.) Don't trust the voltages/currents shown on the screen of the controller. They are often there just to give a very rough sense of power delivered.

[epsgunner]

Outside playing with my dead (amp wise) battery.. its VERY cloudy and 83'F..

12.6V and 0 amps reading on the TS45 (with the PV array off).

I checked the TRUE solar volts after the combiner box at the controller.. 20.7V with a meter..

I then turn on the 1 panel 145w solar array with the breaker..

on the main battery screen I now get

12.9 V on the battery (and going up) and like 1.9 amps and 25 watts..

I get 13.2 V listed under that separate solar panel display area in diagnostics.

25 on the meter and 39.33 (20.7* same 1.9 Amps).

So it would appear I am loosing like 15 watts of difference of the panel input..

So simple math would be 145w (Rated) - 15 watts of spent watts based on these numbers.. = 130 watts..

I don't have any inverter yet to test draw down and such... and this BAKED battery isn't helping the matter..

[epsgunner]

I'm unsure then I guess.

I have the Morningstar TS-45 PWM, and not the MPPT version..

My TriStar meter measures solar voltage from panels from a high of 16.39 V to a low of 14.39V..
(if I had the MPPT it would give me more information.. such as logged min/max volts and such)

The front screen for the battery numbers says about 14.8V 110w and 7.4 amps at 99% PWM..

Then its goes to BULK and 14.4V, 112w and 7.6 -7.8amps.

110w is 77% of the rated 145w sticker..

The AH meter said 16.2 AH for 2 hours..

Again I am unsure of what I have as I don't have an incoming WATT meter..

[Sunking]

Sunking.. thanks.. currently I get my 77% to my controller/battery (with testing I am doing)..

If you are speaking about from panel to output of controller then you have a problem. With wiring from the panels and controller losses you should be at less than 10% loss (4% for wiring and 5% for controller). You are claiming 23% loss or 77% efficient. If the panels are generating 100 watts, then at the output of a MPPT controller you should be seeing something like 90 to 93 watts to the batteries. There is a problem somewhere if you were only seeing 77 watts out of 100.

[epsgunner]

You put 1 in as that is as low as the program will accept and then multiply the results by .725

It does take .725 for the KW.. just tried it.. numbers DO work the same as what you said if I did go that route..

Sunking.. thanks.. currently I get my 77% to my controller/battery (with testing I am doing)..

I'll knock it back abit, but not 52%.. my 3/0 wire 3.5 feet and 0.90 eff inverter should keep me at like 62-68% is my guess.. the current draw is like 0.8 amp at rest.

I just wanted to get the irradiance factors for the angles.. not the $ or AC KW numbers..

[Sunking]

Thanks.. I'm at 30.69 lat. on my TX property (where panels will be) facing directly South.

EPS if I remember correctly you have a Off-Grid Battery system right? If so unless you changed the efficiency to 50% then the PV Watts Data is invalid because its default is set for 77% for a Grid Tied system

[russ]

I used Austin and a 1 kW system for the following - 30

[russ]

I'll ask the dumb question..

If my NAMEPLATE panel total is 725 (145*5) watts.. do I put .725 in the DC Rating (kW) entry??

Or do I put the total of 5 hours * 725 in that entry??

You put 1 in as that is as low as the program will accept and then multiply the results by .725