Slightly disappointed if I'm honest today......

[liquidity]

I have a temp probe under one of my panels and have yet to see more than 40 deg C so far this year. So me thinks temp related power loss is minimal - it's just slightly hazy sunshine.

 

[SolarCity]

You'll be surprised at just how hot panels can get, even in slightly warm conditions.

As has been said above, Sanyo panels perform better than other panels in heat but they're still affected.

One of our customers did an experiment last year where he cooled the panels with a hose pipe. The effect was similar to what MEP described - instant increase in yield. He was considering designing an irrigation system I believe.

 

[langstroth2]

I have a temp probe under one of my panels and have yet to see more than 40 deg C so far this year

Assuming that panels aren't made of particularly good thermal conducting material, I would have thought though the temperature on the upper surface could be considerably more - dark material under glass....

Our HW panels were up around 70C yesterday, unlike PV they are obviously designed to convert radiation into heat, but it goes to show that the energy is there to be captured given the right material.

 

[Gavin A]

the top of the panels definitely will be hotter than the underside, and even at 40 degrees that'd be a 4.5% reduction over the nominal for sanyo's.

 

[danesol]

..................One of our customers did an experiment last year where he cooled the panels with a hose pipe. The effect was similar to what MEP described - instant increase in yield. He was considering designing an irrigation system I believe.

OK, as suggested by MEP, I tried this at a few times between 12noon and 1pm when our power was at its best

It made a difference no doubt at all ...... however for us at this time of the year it was only between a 10 to 20watts increase for the 12panels

I may experiment further with this now in the coming Summer months ...... LOL

 

[Mozzerr]

Today was an apparently cloud free day for us and consequently the graph of our PV generation is as close to the perfect hyperbolic curve as I reckon it is ever going to get!

So I too could not resist the temptation to see if the hose pipe would show an effect on my graph - especially when compared to my dad's identical PV system down the road!

And here's the proof! Me standing on a ladder spraying the array for just a few minutes had a definite and obvious effect on yield - as demonstrated by this graph on PVOutput.org...

Compare Live

So I think the irrigation system is definitely worthy of some consideration!

 

[VMan]

i thought perhaps a load of TEC / Peltier's on the rear of the module, connected into is own mppt inverter?!? then using the heat from the panel and maybe some aluminium fins on the back to air cool, there we have a 'hybrid' panel!

the TEG's should also take some heat away to make the PV more efficient...
anyone want to form a partnership?

 

[Gary K]

Today was an apparently cloud free day for us and consequently the graph of our PV generation is as close to the perfect hyperbolic curve as I reckon it is ever going to get!

So I too could not resist the temptation to see if the hose pipe would show an effect on my graph - especially when compared to my dad's identical PV system down the road!

And here's the proof! Me standing on a ladder spraying the array for just a few minutes had a definite and obvious effect on yield - as demonstrated by this graph on PVOutput.org...

Compare Live

So I think the irrigation system is definitely worthy of some consideration!

What time did you spray the panels?- is it 2.30pm where the mini bump is in the graph?

 

[danesol]

I think this leads me to my next question, I wonder if any of the big manufacturers have ever looked into combining Solar Thermal with Solar PV to produce a true hybrid that does both, helping each other ?

 

[solarsavings]

Yes they have and cant get it to work well enough to bring it to market with the exception of one italian company whose name escapes me at the moment.

 

[Mozzerr]

What time did you spray the panels?- is it 2.30pm where the mini bump is in the graph?

Exactly! I meant to mention the time in my post... But you've just proved that it's a very real and obvious effect! And I was literally up there only a few minutes just long enough to cover all the modules in water!! So I imagine a proper cooling system would have an excellent benefit!... Worth thinking seriously about.

 

[prof. popkiss]

Cooling your panels to improve their output is an interesting, if short-lived effect, so is not of much practical use. However, if you can reach your panels with a hose, it may be worth giving them a short shower from time to time to remove surface dust. I tried this yesterday on my 4kWp system, having noticed that the panels were dirty and saw an immediate 170W increase in output. This gradually decreased to about 150W as the panels warmed up again.

It may seem a lot of trouble to go to for such a modest improvement, but even so, if you can boost your output by 150W for say 12 hours by keeping your panels clean, that's still 1.8 units extra per day.

I don't know what effect repeatedly hosing hot panels with cold water would have (thermal shock) so it may be advisable to do this early in the morning or late in the evening when the panels are cold.

 

[danesol]

I don't know what effect repeatedly hosing hot panels with cold water would have (thermal shock) so it may be advisable to do this early in the morning or late in the evening when the panels are cold.

Lets hope your wrong then about thermal shock, as we have April showers to get through soon - lol

 

[liquidity]

Some temp data for today:
ambient: 12 C
roof tiles: 52 C
underside of panels: 35 C
top side of panels: 35 C

all measured with a IR thermometer.

light breeze, perhaps 2-3 mph

 

[flyman]

Perhaps this is the birth (or maybe just the conception) of a hybrid PV/Solar themal system idea.... Why waste all that heat?