CIGS vs Silicon

[lotech]

I am newbie in Solar energy and experimenting with different panels, I got a 4W Amorphous panel and a 6W CIGS panel, I put them to the test on a half sunny day. I find the Amorphous panel put out as much as 50% higher open voltage than the CIGS one, I got 18V on the Amorphous and about 10v on the CIGS, when put under full sun both panel perform near the same but the Amorphous one still put out little more. I read that CIGS panel performs well in low night but the test result doesn't support that, I don't know if my panel is faulty or it hasn't been soak in the sun long enough.

[spadlet]

There are a lot of factors which may have influenced your results. For starters, what are you basing your expectations on? Are you comparing like for like performance predictions for the two panels?

CIGS is a type of thin film technology. Thin film photovoltaic panels can have a potentially better spectral response because the layers are VERY thin. This means that you can have a number of different layers which absorb different parts of the light spectrum better. The ammount of benefit that this provides will depend upon your location. The further north you go in the northern hemisphere, the greater the proportion of light in the blue part of the spectrum. The improved spectral response from the thin film panels should increase the ammount of this blue spectrum light that is absorbed and thus increase the ammount of solar resource that the panel can use. Do you think that this is the issue the literature you were reading is refering to?

[lotech]

My test in no way scientific and the sales ad fooled me, I don't see what I expected to see that's why, further more I am far from northern hemisphere. The disappointment won't stop me to get deeper into CIGS or the like, non Silicon is the future.

[spadlet]

Originally Posted by lotech

My test in no way scientific and the sales ad fooled me, I don't see what I expected to see that's why, further more I am far from northern hemisphere. The disappointment won't stop me to get deeper into CIGS or the like, non Silicon is the future.

I wasn't trying to criticise your trial. It's always worth checking things out for yourself, if you have the time and money to spare . If you know much about engineering there are some really good books about the science involved that you might also find interesting, if you dont know much about the science behind the technology it's well worth taking the time to find out, if you feel like it. There seems to be alot of misinformation flying around which is a shame because it makes it even harder to discuss the advantages of various technologies when people feel that they have already been misled.

Things about CIGS that do seem to be true are that they are cheaper to produce than silicon photovoltaic panels and they seem to be exhibiting a better thermal performance. (Electricity production doesn't decline as much when the temperature of the CIGS panel increases). Thermal performance inprovements might be an area where they have advantage over silicon cells in hotter countries. A couple of other things that you might lie to consider with your CIGS panel is that there seems to be a degredation period after the initial instalation, so it might be worth leaving your panels set up for a longer time period before you make your comparison and comparing their performance during the warmest parts of the day. You might find that your CIGS panel performs better when it's more sunny. It might also be worth checking any information you got with your CIGS panel to see if the conversion efficiencies/output data are given for the period before or after the initial degredation in performance. Also, you have the cells and I dont, so it would be great if you could prove the information I've been given wrong .

If you want to try and find out a bit more about the technologies I can try to answer your questions as best as I can (and refer you to things that might help you make your own mind up). CIGS is only just becoming mainstream so there might be a few changes etc in the short term and it might take people a while to become used to the technology. What are you planning to do with your photovoltaic panels now? If you own them or have access to them for longer you could try some more comparisons to check out more stuff if you wanted.

Best of luck with things, hope you stick around and keep sharing your experiences

[lotech]

I purchased some low power panels of different type including Amorphous, thin film and CIGS, mainly for charging up gel battery and supply to small appliance like radio and notebook. As far as I know Silicon mono crystal has the highest efficiency thus highest output, but all Silicon panel suffers degradation over time, on the other hand CIGS will get better after soak in the sun, that's all I know.

[Besoeker]

Originally Posted by lotech

I am newbie in Solar energy and experimenting with different panels, I got a 4W Amorphous panel and a 6W CIGS panel, I put them to the test on a half sunny day. I find the Amorphous panel put out as much as 50% higher open voltage than the CIGS one, I got 18V on the Amorphous and about 10v on the CIGS, when put under full sun both panel perform near the same but the Amorphous one still put out little more. I read that CIGS panel performs well in low night but the test result doesn't support that, I don't know if my panel is faulty or it hasn't been soak in the sun long enough.

When you say "open voltage" I assume open circuit voltage. That is, when not supplying any load power. That alone isn't a very good measure of performance.
For a like-for-like comparison, you'd really need to measure power output from each under the same conditions.

[lotech]

If the panel does not reach 12V unloaded, then it is no use for charging a 12V battery, further test is meaningless, pick a better day for the test.

[spadlet]

Originally Posted by Besoeker

For a like-for-like comparison, you'd really need to measure power output from each under the same conditions.

You should be able to obtain an I-V (current-voltage) curve for each photovotaic panel that you buy, You can in the UK at any rate. They are supposed to be individually tested so that people doing large installation projects can match the exact preformance of the modules when deciding how to connect them together. Differences in performance of photovoltaic panels coneected in series can reduce the performance of each panel in the series to that of the lowest performing module so the data can be very useful and important. Have your modules come with I-V curves?