Solar Panels Lose Efficiency When Too Hot

Try here...

http://en.wikipedia.org/wiki/Solar_cell#Cell_temperature

Thanks mjb

I remember larger losses mentioned in the CR4 thread I read not to long ago. Maybe my memory is playing tricks on me. The reduction in efficiency seems negligible in the section you have supplied. Very helpful.

Thanks, Ky.

Not really negligible. If cell temperature rises from 20°C to 100°C (delta 80°C), then efficiency could drop 40%. I'd consider that significant. With the roof top temperatures around here lately, this level of temperature rise in direct sun seems quite possible.

Thanks mjb1962853

I am a layman regarding this and am not familiar with the formulas. You are right, that is very significant, unbelievable really. You have no idea how much this information helps me. I am concerned with a different approach, technology which could drastically reduce these effects with out even touching a solar panel.

Not long now and I'll be able to post details of this in CR4. Homework first and plenty of it. Thanks again, Ky.

Is it possible to get 100 deg.C eventhough the ambient temp. would be less than 50 deg.C?.Being new to the subject but would like to know how 100 deg.C can be achieved.

Yes, if your assembly is very well insulated so as to minimize heat loss and enough solar energy is focussed onto it.

Dear friend.

The efficiency should drop. After all, electrical resistance of solids increase with temperature resulting in greater voltage drop and losses.

Are you concerned with your PV panels losing energy? If so, maybe you might want to consider this solution. Install a cooling system to circulate water around the panels. In this way, you help to keep your panels cool, improving their efficiency while geting free hot water at the same time.

Wow, you are very close to what I have planned but just not close enough. I was thinking along those lines just using a different set up. Like I said, I will be in a position to publicize what I am on about soon. It is just an additional aspect of something I have been working on.

I should have thought of the resistance of solids my self but need a nudge once in a while. Its self explanatory isn't it?

If there is a dark side to the force there must be light and we'll meet in the middle one day, I hope, Ky.

Hi,

First thing, Solar PV is good option to generate electricity at small scale.

If you plan for setting up large multi MW grid feeding Solar Power Generation projects, the one that we are trying to build, in India under JNNSM of GOI, then Solar Thermal is far better option.

Solar Dish Stirling Engine systems is the best solution among all other solutions available.

Regards

Madhav Chowdhary

sweetechnologies at gmail dot com

+91-9623557207

Pune (India)

I believe this is what you are looking for. When does the dude get back... to tell you where you put things?

chris

Good stuff Chris

That is the one I was talking about. Perfect!! Were would I be with out you????

The dude got back but he can hardly talk. He had an accident on his travels but the Hospital stuffed up and made things worse. The medication he is on now makes it hard for him to even remember his name, not to mention what I did not register on my on-board computer. I mean that soft material between my ears.

You know, at the time I read this thread it didn't seem obvious that the information would be relevant. Once it goes in on one side it leaves the other with out much of a trace. Me bad! It will improve with age, I hope.

Hope a GA helps, Ky.

I'm not so sure about this. As far as I'm aware latest Photo Voltaic panels are utilised in "Concentrated Photo Voltaic" systems where system of heliostats/mirrors focuses sunlight power onto the Photovoltaic panels to increase electricity production. Quite often these panels are used to harvest heat energy as well. Combined thermal and PV systems.

Hello,

Do you know what happens to the CPV cells, if the cooling system fails.

Also the critical design of concentrators / reflectors when it come to CPV Cell based power generation

And in this world, if something can go wrong, it will always go wrong.

You can repair / bring the cooling systems on track.

But CPV cell can not be repaired.

Regards

Madhav Chowdhary

SWEE Technologies

sweetechnologies at gmail dot com

+91-9623557207

why do you think for large units (MW level) solar thermal is more cost effective han solar elect panels ,without storage facility( that is grid connected) ?? why then in India many solar power installations being done with solar panels?

Hi,

There is total confusion in India regarding MW level Grid Connected Solar Power Project Development activity.

The people who are taking decisions are trapped in mad rush to get allotment, without properly taking technical decisions.

There is no Project Developer in solar thermal sector who is ready to supply small solar thermal power generation plants, having capacity less than 25 MW

Companies already established in solar thermal project development are not interested in small projects.

Regards

Madhav Chowdhary

for a quick easy shortcut use this link

http://www.solren.com/stringSizing.html

Solectria PV inverters has a nice string sizing setup.

What I like is it gives you the temp correction factor for each tested panel and the multiplier based on temperature.

PS. if you live in a colder region, there is also a temp correction factor for panels running too cool.

Table 690.7 Voltage Correction Factors for Crystalline and

Multicrystalline Silicon Modules

Correction Factors for Ambient Temperatures Below 25°C

(77°F). (Multiply the rated open circuit voltage by the

appropriate correction factor shown below.)

Ambient

Temperature (°C) Factor Temperature (°F)

24 to 20 1.02 76 to 68

19 to 15 1.04 67 to 59

14 to 10 1.06 58 to 50

9 to 5 1.08 49 to 41

4 to 0 1.10 40 to 32

−1 to −5 1.12 31 to 23

−6 to −10 1.14 22 to 14

−11 to −15 1.16 13 to 5

−16 to −20 1.18 4 to −4

−21 to −25 1.20 −5 to −13

−26 to −30 1.21 −14 to −22

−31 to −35 1.23 −23 to −31

−36 to −40 1.25 −32 to −40

PSS PV cells are basically resistors, the hotter they get the less efficient they become

Hope this helps

EV1guy2004

I hope I can assist and help you with something one day. Very helpful. Thank you for knowing what you know and sharing it. Happy to have you here in CR4, Ky.

Thanks for this info. which effectively translates, loosely, into 0.5% per deg. C, drop in temp. Is the same ratio applicable for increase in temp. also.

To share an experience, we supplied a solar controller which was installed on a gas pipeline station in Western Rajasthan in India ( almost Thar desert ). At approx. 50 deg. C ambient temp.it was noticed that the open circuit voltage and peak power point had shifted lower by approx. 1.3 V.

Thanks

Ashok Toshniwal, Bangalore, India.

I understand many people don't trust anything found on wikipedia, but in this case it does contain some useful information. Post #1 provided a wiki link with general thermal characteristics of solar cells.

"Most crystalline silicon solar cells decline in efficiency by 0.50%/°C and most amorphous cells decline by 0.15-0.25%/°C."

This is a good general calculation suitable for most people. Further research is of course recommended if the application requires more precise data.

Thanks for this info too, and also on details about amorphous cells. I should have been more clear in my earlier question.

Thanks and regards

Ashok Toshniwal