what is the better panel?

[J.P.M.]

Actually the power rating is the sum of the VMP which is voltage at maximum power and IMP which is current at maximum power but of course real world numbers are different and some panels actually have more realistic numbers as well on the back I know Kyocera panels do. You can see here on this Kyocera 135 watt panel that the real world number is more like 97 watts
Kyocera KD135.jpg

You are correct.
I made an error in not specifying the (Vmp*Imp) product as the power rating at STC.
Apologies to the OP and the membership for my error.

J.P.M.

[Alsatian1234]

Thanks for the info and help, appreciated.

[littleharbor2]

Actually the power rating is the sum of the VMP which is voltage at maximum power and IMP which is current at maximum power but of course real world numbers are different and some panels actually have more realistic numbers as well on the back I know Kyocera panels do. You can see here on this Kyocera 135 watt panel that the real world number is more like 97 watts. I believe this is called the NOCT which stands for normal operating condition test ,I think
Kyocera KD135.jpg

[J.P.M.]

They are the same price per panel and there is no other form of electricity. What i do not understand is the way they are calculating the 400 Watts peak. How does that work out in less than peak weather? One panel has higher peak than the other.

The panels are but one expense.
Don't cheap out on the balance of system or particularly the labor or the quality of the installation.
You will quickly come to regret it.
And, while you're at it, make sure you have a reliable electrical energy backup, most usually a fossil fueled generator is chosen.

Usually, the rated panel output is calculated under what are called "Standard Test Conditions", or "STC" and measured under controlled indoor conditions using a radiative source with an intensity of 1,000 W/m^2 and a spectral output distribution of that source close to that of the sun at sea level.

Usually, the product of the open circuit voltage and the short circuit current works out to be pretty close the STC power rating.
I don't know what your sources are using but it doesn't look like what I'm familiar with.

Under day-to-day operating conditions and throughout any day the instantaneous output and so the daily output of a panel or a system in kWh/day will be less, usually by quite a bit, than the STC rating multiplied by the number of hours of sunshine for any particular day.

See/Download a free PDF of "Solar Power Your Home for Dummies". It's slightly dated but should help you answer your own questions in more detail.

[Alsatian1234]

They are the same price per panel and there is no other form of electricity. What i do not understand is the way they are calculating the 400 Watts peak. How does that work out in less than peak weather? One panel has higher peak than the other.

[J.P.M.]

Without knowing more about the application, I'd suggest it's a tossup.
I'd add that under the environmental conditions you briefly describe, you're probably going to have a long time before any financial breakeven, but like most everything else in life, going low cost for everything is false economy.

[Alsatian1234]

It is an area with less sunny days and higher altitude

[Alsatian1234]

I have a choice of 2 different panels at the same price. I would like to know which one is better to use on the long term if I want to string 6 or so to get 220v, in an area with low light conditions for most of the year. I understand that it is some sort of bell curve and anything above the battery voltage is what the panel actually puts into the battery. I want to use a cheapo controller not anything fancy. advice? Thanks
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