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

 

[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?

 

[mattiker]

Hi,

Just out of interest - my 2.5KW system mostly south-south-west facing with micro-inverters - has only peaked at about 1.9KW but the actual output KWh looks largely in line with what most others are getting - I've printed off an estimate from PGVIS which has the average output per month/day through the year which I use as a benchmark (e.g. March should average 5KWh per day, 155KWh total). The installers estimated 2100KWh for the year but PGVIS estimated just under 2000KWh - I'll be happy with anything in-between.

The point I wanted to make was this.....when the scaffold was still up I was doing some roof work and noticed that my panels, Risen 250 SYP, had some condensation on them- it was a cold morning and the sun was still low. However my neighbours panels, SANYO hit250's had no condensation at all.....this suggest the sanyo panels have a lower thermal mass, which by my guess must be in part why they perform better in hot conditions.

 

[Jaycee]

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

Saw just the thing at Ecobuild!

 

[finchy]

like the idea of that makes sense .....I'm adding thermal to our portfolio in the coming months !!

 

[langstroth2]

Interestingly, today a brief peak at 3,804W - the highest peak I've seen on our 4kw system (far higher than than during the recent blue skies, where we barely reached a peak of 3kw).

I put this down to:
- we actually had some wet stuff falling out the sky that had washed the panels clean
- they were cool, the sun having only just popped out from behind the clouds

 

[VMan]

Hi,

Just out of interest - my 2.5KW system mostly south-south-west facing with micro-inverters - has only peaked at about 1.9KW but the actual output KWh looks largely in line with what most others are getting - I've printed off an estimate from PGVIS which has the average output per month/day through the year which I use as a benchmark (e.g. March should average 5KWh per day, 155KWh total). The installers estimated 2100KWh for the year but PGVIS estimated just under 2000KWh - I'll be happy with anything in-between.

The point I wanted to make was this.....when the scaffold was still up I was doing some roof work and noticed that my panels, Risen 250 SYP, had some condensation on them- it was a cold morning and the sun was still low. However my neighbours panels, SANYO hit250's had no condensation at all.....this suggest the sanyo panels have a lower thermal mass, which by my guess must be in part why they perform better in hot conditions.

This is good to hear, my 2.4kwp system has only been peaking at 1.9kw too, i think this is quite ok at them moment, hopefully a cool summers day will increase this.

 

[FB.]

Interestingly, today a brief peak at 3,804W - the highest peak I've seen on our 4kw system (far higher than than during the recent blue skies, where we barely reached a peak of 3kw).

I put this down to:
- we actually had some wet stuff falling out the sky that had washed the panels clean
- they were cool, the sun having only just popped out from behind the clouds

It didn't rain here until late afternoon.
The morning had sunny spells, but, like you, I found the inverter was running at a higher output than any time previously.
My assumption was that with less sun, there was less evaporation of moisture from the saturated soil, so less haziness in the sky.
I've certainly felt that my panels could have been doing better in recent weeks, but were hampered by quite a lot of haziness.

 

[Solluva]

I also intend carrying out a few tests running water down the surface of my ground mounted array. I have a choice of water sources namely tap, a stream or if it ever rains again collected rainwater. I have my doubts as to whether tap water is a good idea over the longer term especially if your water is hard. If you live in a hard water area you have only to look at collective dried splashes of the water to see the build up of a film of calcium. This can be difficult to remove and would cut down on the panel’s performance. My tests will also compare the build up of deposits using these different water sources. I will eventually report back on this but please don’t hold your breath.

 

[Harry Worth]

As I understand it - The panel's output is specified at standard test conditions. One of these parameters is air mass which varies throughout the year. Air mass ranges from around 4 in the winter to around 1.5 or less in the summer. 1.5 is the test condition figure. You're only going to see this in the summer. It is possible to get less than 1.5 so you may see better than the power rating although this may be offset by the less than ideal ambient summer temps.

 

[stuart99]

Interesting thread, I've just been speaking to a guy in Australia who is experimenting with water cooling on his panels. Seems to have good performance improvement there, although the ambient temp is around 35oC !