Solar Panels in Hot Weather

[emerika]

I just recently noticed that the maximum power that I am getting from my panels has dropped quite a bit.

I have 12 210 watt panels that should provide about 2500 watts of power at peak. (In fact I've seen numbers higher than this.) Lately I see no more that 1950 watts.

Looking into things I see that each of the 4 blocks of three panels act the same. If I disconnect any block I see about a 460-ish drop in power. If I disconnect all but 1 group, I see about 460 watts.

This is of course near noon. The panels have just been adjusted for the angle to the sun and cleaned. Also I put on about a 2500 watt load.

The fact that in every circumstance the solar panel blocks behave the same leads me to think they are OK. Well, or all are bad in very much the same manner.

So, the question of heat. It's 3:00 PM here and it's still 105F degrees. Does anyone know if the heat could explain this?

Thanks in advance-

emerika

[Sunking]

I assume you live where it gets warm in Summer? If so sounds normal as the power output goes down as temperatures rise.

[russ]

For every degree C above 25

[Naptown]

[QUOTE=russ;26480]For every degree C above 25

[emerika]

Thanks Russ and Naptown-

You seem to have the explanation. Though there is no humidity here, but the temperature at the panels reduces the maximum possible number enough that nothing really seems out of whack.

I'll relax now.

[russ]

Like Rich pointed out - it is the panel temperature that counts.

If you take a contact thermometer (not an IR device) and obtain the panel temperature it would be more correct.

Russ

[FIXMattic]

.... I have 12 210 watt panels that should provide about 2500 watts of power at peak. (In fact I've seen numbers higher than this.) Lately I see no more that 1950 watts.
.....

This is of course near noon. The panels have just been adjusted for the angle to the sun and cleaned. Also I put on about a 2500 watt load.

How are you running a 2500 Watt load when you only have 1950 Watts peak? Just an observation but sometimes it needs to be stated for those who haven't considered it: You should always under-load your supply, never over-load. A safe engineering rule of thumb is normally give yourself 30% operational overhead on any kind of circuit or system design so that you aren't always running at peak because running anything always at peak with no overhead tends to burn things out more quickly due to excess heat build-up and general wear. The overhead rule in this case would give you sufficient working capacity to account for sporadically cloudy days, inverter/transformer/wire transmission loss, and things like heat inefficiency and temporary dirt/dust build-up inefficiency.

[emerika]

How are you running a 2500 Watt load when you only have 1950 Watts peak? Just an observation but sometimes it needs to be stated for those who haven't considered it: You should always under-load your supply, never over-load. A safe engineering rule of thumb is normally give yourself 30% operational overhead on any kind of circuit or system design so that you aren't always running at peak because running anything always at peak with no overhead tends to burn things out more quickly due to excess heat build-up and general wear. The overhead rule in this case would give you sufficient working capacity to account for sporadically cloudy days, inverter/transformer/wire transmission loss, and things like heat inefficiency and temporary dirt/dust build-up inefficiency.

I have a large battery bank and an inverter that can deliver 6000 watts. I was trying to indicate that the system had every reason to use all the available solar power.

When the charging of the batteries reaches the float stat, the amount of power use from the solar panels is enough (when possible) to power your current needs plus something for the float charging.

Which is to say that though the panels can provide 2500 watts you might only see say 700 watts - 400 watts to power the house and 300 for the float charging.

By generating a large load, I meant to use all available power from the solar panels.

brad

[Sunking]

How are you running a 2500 Watt load when you only have 1950 Watts peak?

Simple they are not doing what they think they are doing. It is like making $100 per day but spending $200 per day. Sooner or later math hits them with real numbers.

[Bala]

The way I read Emerika put more load on than the panels have the ability to supply to test how much they are supplying.

Rather than the assumption that they are running 2500w load continuously.