Newb Asks: Does heat effect solar power generation?

[Gregski]

so I am learning about solar panelism, figure it goes hand in hand with EV conversions right? and so here I am in July in California going why are my 100 watt (12 volt) solar panels only "producing" max at 60% efficiency if you will, for example my six 100 watt solar panels only get up to 363 watts, yes we are assuming optimal angle to the sun, unobstructive line of sight, etc well then I see this ladies video where she brings up things like Standard Test Conditions aka STC 25°C / 77°F can you say mind blown!!! here I thought the months of July and August when the temps get upwards of 100°F would be my best production months, and now I am realizing that may not be the case, who knew? I welcome any of your comments and feedback and as always please be gentle I'm learning here





this was just a pic for demonstration purposes, the panels have been moved to a new location since

[arber333]

Yes well solar panels do heat up while they generate power. This can be seen in the afternoon on a clear sky production will actually decrease slightly. BUT if a small cloud would cover those panels they would cool down (because they dont produce power) and the moment cloud leaves the area panels would peak up to 100%!!!
Until after they heatup again...

This begs the question... what if we would cool down the panels? Wouldnt we get better rating but hot water as well?
In our climate this would mean complex deairing system or glycol mix so they wouldnt freeze over in winter. So not everything is rosy...
Maybe in south CA you can get away with this...

[Gregski]

well the temp at the minute is near perfect 76°F yet my powerism suction sucks, I'm capturing 316 watts and it should be closer to 600

[arber333]

Maybe its like with all things. In perfect lab enviroment my panels provide 325W x26 = 8450W , but real life causes them to produce cca 7500W at best. Only in conditions i described earlier they peak up to 8400W for couple of minutes...

[Gregski]

Maybe its like with all things. In perfect lab enviroment my panels provide 325W x26 = 8450W , but real life causes them to produce cca 7500W at best. Only in conditions i described earlier they peak up to 8400W for couple of minutes...

I hear you but 7500W divided by 8450W still gives you 89% efficiency max whilst mine only do 60%, so I will try replacing my 12 volt inverter with the same kind just rated at 24 volts and connect my panels in pairs ie series to yield 24 volt strands, and see if things run more efficiently, fingers crossed


this is my current cheap Grid Tie Inverter off of AMAZON

these are great because no batteries required you just plug this thing into the wall

[muehlpower]

These are two pictures of my 32,760kWp system. The first is a day with passing clouds. The individual DC peaks reach 31.4kW. The second is a hot, sunny day. The maximum value is at 24.5kW

[remy_martian]

Maybe its like with all things. In perfect lab enviroment my panels provide 325W x26 = 8450W , but real life causes them to produce cca 7500W at best. Only in conditions i described earlier they peak up to 8400W for couple of minutes...

I hear you but 7500W divided by 8450W still gives you 89% efficiency max whilst mine only do 60%...

It's not "efficiency" - being a Youtube superstar, you need to stop using that term.

Your problem, based on your photo, is shadows. You cannot have ANY, or the entire array collapses in power generation trying to cook the dark photovoltaics.

NO SHADE. Not a SPECK, or production goes to poop.

Same goes for that hodgepodge of different modules you've connected in series...nope - can't do that either. All photovoltaic cells in a series string (which includes other modules) need to be matched, not those four or five solar module variants you picked up at Goodwill (a store in the US that resells items to the poor that people discard). The bigger cells will cook the smaller ones instead of giving their power to Cheap Charlie Human.

[arber333]

I hear you but 7500W divided by 8450W still gives you 89% efficiency max whilst mine only do 60%, so I will try replacing my 12 volt inverter with the same kind just rated at 24 volts and connect my panels in pairs ie series to yield 24 volt strands, and see if things run more efficiently, fingers crossed

Hm... i do use MPPT optimizers between two cells so better efficiency could be due to buck-boost regulation there...

[Gregski]

so just to clarify all my panels are connected in parallel not in series, and here are three identical 100 watt panels, same make and model, part number, specs underperforming, they should be drawing closer to 300 watts than they are to 100 watts total

[johu]

Might be worth mentioning that the cheap grid tie inverter will piss away another 20% in heat losses and poor mpp tracking. I compared mine to the more expensive Enecsys module inverter and remember a rather significant difference between the two.

[Gregski]

Might be worth mentioning that the cheap grid tie inverter will piss away another 20% in heat losses and poor mpp tracking. I compared mine to the more expensive Enecsys module inverter and remember a rather significant difference between the two.

thank you I was afraid of that, do you think bumping up to the 24v model of the same manufacturer's inverter would improve efficiency? the one I am using is only 12 volts

[philbrennan]

I'm only a newbie to solar myself, but yes to all of the above.
Also you need to break down the problem, reduce the variables/possible causes.
My suggestion, run ONE panel at a time for now. Ensure no shading. Ensure the panel is facing the sun.
Measure temperature of the panel - a laser temperature guage will get you within a few degrees.
You can calculate the expected loss from the panel due to high temp - but at 76F you should be ok.
In clear sunlight you should be able to get something approaching 80 or 90 % easily enough.
If you do then try running some identical panels in series.
Monitor the temp of the panels, is output dropping as temp rises?
If you still can't get near that then ya, maybe there is a serious issue with your inverter or panels.
Running less panels should also reduce possibility that inverter is de-rating due to temp.

I've measured my 415w panels producing up to 98% of their rated output, sustained.
The only thing which I've found to limit their output when conditions are good, is the inverter de-rating due to it running too hot in hot attic - once it goes over 50c it start, I've fixed that with a fan.

[johu]

thank you I was afraid of that, do you think bumping up to the 24v model of the same manufacturer's inverter would improve efficiency? the one I am using is only 12 volts

Won't help much, I've got the 24V model

[arber333]

What i figured from my setup is that PV panels down below make 30% less than those on the roof.
Even light shade will cause panel reduction. Must be some light refraction from all sides or something, but it is true. Maybe you would want to fix those panels up high somewhere out of all shades and out of reach of pets and other animals (kids) .

[Gregski]

What i figured from my setup is that PV panels down below make 30% less than those on the roof.
Even light shade will cause panel reduction. Must be some light refraction from all sides or something, but it is true. Maybe you would want to fix those panels up high somewhere out of all shades and out of reach of pets and other animals (kids) .

thanks, this is where they live on top of the patio cover

[celeron55]

You've connected all those in parallel? Are you running enough copper to not make massive losses in the wires?

You do need to match th voltage also. Do they get to matching voltage when disconnected from each other?

[Gregski]

Might be worth mentioning that the cheap grid tie inverter will piss away another 20% in heat losses and poor mpp tracking. I compared mine to the more expensive Enecsys module inverter and remember a rather significant difference between the two.

determined to prove Johannes right, I decided to throw some money at the problem, to get some INFORMATION





so far I have been monitoring what comes out of the Inverter ie the AC output but now let's see what's actually going in

[Gregski]

[Gregski]

it's how we do....

[Gregski]

Now this thing will do ONE out of THREE things that I like these sorts of meters to do

1. It will show us data in real time (Volts, Amps, Watts, & even Amp Hours)

2. It will NOT log any hysterical data for us to have a record over time with

3. It is not blue toof nor WiFi meaning we have to be where it's at to see the data


[ all of this pronounced: better than noffin' ]

and the best part is no CANBusin' required my kinda gizmo, just wire it up and it goes....


ok this was early in the morning like at 7:00 AM before the sun woke up so it was only reading 19 Watts but at least it be a working! Yes

[Gregski]

100 WATT REPORT Update

alright we have some data to compare, at about 72°F early in the morning in August we had 113 watts DC coming in to the inverter and 104 watts AC coming out, so that's 92% efficiency when it comes to how the sausage is made unless I am missing something, of course we will do this throughout the day as temperatures rise, the idea being check out the effects of heat on the inverter itself not the solar panels

[Gregski]

200 WATT REPORT Update

76°F of morning sun
228 Watts DC input
204 Watts AC output

89% efficient

[Gregski]

300 WATT REPORT Update

82°F of late morning sun in August
302 Watts DC input
300 Watts AC output

99% efficient

[muehlpower]

Were the measurements made with 3 or 6 modules? With 3 modules it would be a good value! The measured AC value could be corrupted by an imperfect sine wave.

[Gregski]

Were the measurements made with 3 or 6 modules? With 3 modules it would be a good value! The measured AC value could be corrupted by an imperfect sine wave.

modules? or did you mean panels? I am currently using six 100 watt Windy Nation solar panels, and I'm beginning to think they suck!

I just came across this video, fyi it came out after I already bought my Windy Nation panels