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

[danesol]

AFAIK my PV System is running 100% with no issues..... and have received some great returns, unbelieveable infact over the last few mths, but today we get the best weather ever and it only peaks at ~2.5KW !!!

Its a Sanyo HiT240 / Sunnyboy 3000HF based system btw

The only issue I can see is that its very slightly misty high up......... however I was hoping to hit 3.2KW today at noon :sad_smile:

Anyone got any thoughts on this................

 

[FB.]

In the last several days, we've had some amazing weather, but there has been a slight haze which has weakened the strength of the sun actually reaching the ground (or the panels) and it has meant only slightly-above-average daily generation due to the haze acting like a cloud. I'd say that my system has also only been peaking in the 2.5kW range in most days in the last week (3.75kWp system).

Today we had some periods of strong direct sunshine but none of that haze. When the sun was on the panels, in those very bright sunny periods, the inverter went mad; running at 95% of maximum capacity and the cooling fan sounding like a room full of whirring computers, a server-room or a small vacuum cleaner.

So, yes, haziness is as bad as partial cloud cover.

 

[Eco Deal]

My father in law as just bought a system from us

So when it was balzing down with sun yesterday ,

I rang him and said ,

Get your hose pipe out and cool the panels down see if the power goes up .

So he sent his wife up the scaffold lol

and she sprayed cool water on them while my father in law watched his sunny beam -

before cool 2.3 kw
during cool off 2.9kw

of course this may just have been down to the light conditions!!!

worth a try ..



not sure if his wife is still up there or not

 

[danesol]

I'll try that next time and report back...... however i was under the impression thats why you buy the HiT panels as they arentr effected by heat ??

 

[mickys86]

My father in law as just bought a system from us

So when it was balzing down with sun yesterday ,

I rang him and said ,

Get your hose pipe out and cool the panels down see if the power goes up .

So he sent his wife up the scaffold lol

and she sprayed cool water on them while my father in law watched his sunny beam -

before cool 2.3 kw
during cool off 2.9kw

of course this may just have been down to the light conditions!!!

worth a try ..



not sure if his wife is still up there or not

Hose pipe ban where I am...... Shortage of water apparently -must be everyone trying to cool their solar panels lol

 

[Sparky Ninja]

Increase in temperature will have a negative effect in your systems voltage and power (something like -0.5% per degree from 25 degrees C).

You can expect an improvement in your system on sunnier days if it results in more light hitting your array (maybe a better penetration through shading for example). But if the temperature also increases then it will result in a negative effect.

 

[Eco Deal]

the panels lose 1v per 1 oC over 25oc !!!!

I install a lot of yingli , Samsung not alot of sanyo since late 2011 due to tariff drop and everybody panic buying them !!!

 

[danesol]

Increase in temperature will have a negative effect in your systems voltage and power (something like -0.5% per degree from 25 degrees C).

You can expect an improvement in your system on sunnier days if it results in more light hitting your array (maybe a better penetration through shading for example). But if the temperature also increases then it will result in a negative effect.

the panels lose 1v per 1 oC over 25oc !!!!

I install a lot of yingli , Samsung not alot of sanyo since late 2011 due to tariff drop and everybody panic buying them !!!

I have Sanyo HiTs - this is what they are designed for to be uneffected by heat ..... besides it was only 21deg MAX here.....

 

[Gary K]

I have Sanyo HiTs - this is what they are designed for to be uneffected by heat ..... besides it was only 21deg MAX here.....

I assumed it was the temperature of the panels,not the ambient temperature

 

[danesol]

I assumed it was the temperature of the panels,not the ambient temperature

Ar OK, hence why I need to try the water hosing next time................

 

[yellowvanman]

The voltage degredation on panels due to temperature is usually displayed on the panel spec sheet and they all have a different figure per deg C.

 

[Gary K]

I wondered if water could de used to cool the panels-was considering setting up a pipe system with water recycled from a large butt to cascade a thin lair of water across the full surface of every panel. I wasn't sure if the advantage of cooler panels would be lost to reflection off the water

 

[langstroth2]

I have Sanyo HiTs - this is what they are designed for to be uneffected by heat ..... besides it was only 21deg MAX here.....

All panels are effected by heat, even Sanyo HIT's - just less so than some others.
The panels can easily reach 60C plus in direct sun, even if the ambient temperature is 'only' 18C (I think we're still in March, feels more like May).

Here's a table of a few panel types and the effect of temperature on output. The figures are based on the (manufacture claimed) panel specs not actual measurements

 

[langstroth2]

It was a very good day today - we generated 20.2KwH. However, as you say, our 4kwp system peaked at 3.144kw.

 

[Gavin A]

sanyo panels are still affected by the heat, just less so than most other panels. It's a power loss of around 0.3% per degree for Sanyo vs 0.45% per degree average for most standard mono / poly crystaline panels.

probably a combination of haze, panel temp due to lack of wind, and the sun still not being perfectly perpendicular to the panels at this time of year (on most roofs anyway).

 

[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