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Why not CIGS?

0rion

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Hi, just wondering about why CIGS panels haven't really taken off for RV use in particular.

I've seen that with many discussions of CIGS flexible solar panels that folks seem to get them conflated with some of the drawbacks of flexible crystalline panels, focusing on the 'flexible solar panel' part; namely that they're fragile and have low yield efficiency - but not necessarily...

CIGS seem to be:
* Durable - not prone to microcracking, cells are robust to the point of puncturing. Seems better suited to the 'rolling earthquake' of an RV roof.
* Efficient - while overall efficiency may be less than crystalline, they're more effective in the shade (one company even advertises that each cell has a bypass diode so you really only lose the power of the one shaded cell, not the whole string) - a trade-off that seems better for RV/vehicle use
* Better at handling high temperature power losses
* Better at utilizing a wider spectrum of light - more power production during overcast days and low sun angles
* Have warranties comparable to rigid crystalline panels

I've heard @Will Prowse mention them in passing in a video, I'd love to get a more in-depth analysis though - for my RV I've been hesitant to get flexible panels due to the drawbacks others have mentioned, and can't seem to commit to heavy rigid panels that will need to be drilled to my TPO roof, and may not do as well in shaded/overcast environments. The CIGS flexible panels seem to be the goldilocks solution...am I missing something?
 
These are the panels marketed towards military and sometimes marine/offroad applications?

From what I remember when I looked into them (briefly) they were fairly cost prohibitive for anything that didn't absolutely require the ruggedness/durability, or wasn't a luxury build where cost was not a factor.

The company you pointed to sells 105W panels for ~$450 and 180W panels for ~$750
Another company I am aware of that uses this sort of panel charges $6000 for a 500W walkable 'roof deck' which is cool but exorbitantly priced.

I think the above (cost), the significantly lower Watts/Meter, the fact that there are not a ton of companies selling or marketing these panels direct to consumers, and the fact that there just isn't a lot of awareness/info about this type of panel (and as you mentioned-- confusion with cheaper flexible panels), is part of the reason you don't see them discussed more. But I think #1 is definitely cost.

I do see value, in some very specific applications, and would be happy to see more technical discussion/info about this type of panel on the forum
 
What do you see as the advantages and disadvantages of this style?
Is there any tech data as to the temperature coefficients?

From a brief look:

Pros:
  1. Flexible & Thin
  2. Lightweight
  3. Durable
  4. Possibly better partial shade performance
Cons:
  1. Extremely expensive per watt
  2. Low efficiency compared to rigid panels (between 1/2 and 2/3 as efficient)
  3. Technical info is somewhat harder to find
  4. Harder to source
 
What do you see as the advantages and disadvantages of this style?
Is there any tech data as to the temperature coefficients?

From a brief look:

Pros:
  1. Flexible & Thin
  2. Lightweight
  3. Durable
  4. Possibly better partial shade performance
Cons:
  1. Extremely expensive per watt
  2. Low efficiency compared to rigid panels (between 1/2 and 2/3 as efficient)
  3. Technical info is somewhat harder to find
  4. Harder to source
For me, the efficiency is why I don't buy more. And the price! They are very cool though. I love my golf cart panel.

Traditional silicon solar cell panels are just cheap and very easy to use. And very efficient.
 
Thanks for your replies! Interesting discussion.

Regarding cost/watt, I'll concede to this point (especially as a Canadian). But what exactly do we mean by efficiency - the fact that CIGS tend to be around 17% where monocrystalline cells can be 23%? Wouldn't that mean (and I may be misinterpreting the meaning) that a 100w CIGS panel would need a few more cells, or a larger footprint, compared to a 100w mono? Isn't comparing a 100w CIGS to a 100w silicon panel like apples to apples? We know that you might see 80w from that panel when pointed at the sun, but when shaded that mono panel may go down to 30w whereas the CIGS may still give 70w under the same conditions. So which one is more efficient now?

For Temperature Coefficient, it's hard to say what the real world power production would be - in the marketing brochure the numbers look better for CIGS over most crystalline, on par with the high quality Sunpower cells (~0.36%/degC vs mono 0.45%/degC).

For a rooftop (or driveway ;-)) setup where panels can be positioned for best access to the sun, I agree that traditional cheap silicon is the way to go...but for RV/Van/Overland use where the demand for solar power is highest in unpredictable locations with varying obstructions I wonder if you wouldn't need to spend the same amount on several silicon panels to get the same real-world output of a CIGS.

Con: not nearly as durable/shorter lifespan as compared to rigid.

Also. See here for pro/con discussion :

Interesting article, but many of the points regarding durability and longevity again pertain to panels with silicon cells, not the CIGS which seem to have warranties on par with rigid.
 
Here is a more specific article showing a greater reduction in output per year for CIGS :


To quote from the article:

The rated power output of solar panels typically degrades at about 0.5%/year. However, thin-film solar panels (a-Si, CdTe and CIGS) degrades faster than panels that are based on mono- and polycrystalline solar panels lifespan.

But I have no application for flexible panels myself, just trying to add to the discussion.

If you have the budget and an application calling for flexible panels it’s a good choice for sure.
 
But what exactly do we mean by efficiency - the fact that CIGS tend to be around 17% where monocrystalline cells can be 23%?
I'm only going off of the link you posted earlier, which shows 11% not 17%, maybe there are others with higher efficiencies?
If there are 17% efficient CIGS modules that changes the equation somewhat.

Wouldn't that mean (and I may be misinterpreting the meaning) that a 100w CIGS panel would need a few more cells, or a larger footprint, compared to a 100w mono?
Yes, I think you have a handle on it, a less efficient panel (or cell) requires more area to generate the same power in the same conditions.

Isn't comparing a 100w CIGS to a 100w silicon panel like apples to apples? We know that you might see 80w from that panel when pointed at the sun, but when shaded that mono panel may go down to 30w whereas the CIGS may still give 70w under the same conditions. So which one is more efficient now?
You are talking about partial shade performance, not efficiency in the sense it is used when talking about PV. This is one of the most interesting features of the panel you linked to (bypass diodes per cell). I remember reading there was a crystalline panel that used bypass diodes per cell at one point to, but it is not on the market anymore as far as I know, I think the cost/complexity/benefit made it hard to find a market.

As to your broader point though, I think some real world testing would be really interesting, its not easy to say what panel would be better over the full range of scenarios a panel might see on a vehicle or boat for instance. CIGS panels may or may not perform meaningfully better in the shade, and that may give them an edge in that situation, but they take more space to do so, meaning they will generate less in sunny conditions, and possibly generate less in hot conditions (I cant find any data on temperature coefficients, do you know?) so the shade performance would need to make up for this overall deficit.

For Temperature Coefficient, it's hard to say what the real world power production would be - in the marketing brochure the numbers look better for CIGS over most crystalline, on par with the high quality Sunpower cells (~0.36%/degC vs mono 0.45%/degC).
I just checked three panels, One from REC, one from JA Solar, and one from Canadian Solar and the coefficients for Pmax were -0.26%/*C, -0.36%/*C, -0.36%/*C respectively. So it sounds like they may be about equal here (apart from the REC panel which does exceptionally well with temperature, I think its one of the best on the market right now and not cheap but still substantially cheaper per Watt than the CIGS panels from the link above).

Apart from the temp coefficient, the other temperature related variable that would need to be considered is how hot the panels get in the way they are intended to be mounted, a rigid panel (or non-rigid panel) mounted with free air underneath it, might stay substantially cooler than a flexible panel mounted flat against a surface, especially a metal surface of a vehicle. But I've no idea what the difference might be, in terms of numbers.


but for RV/Van/Overland use where the demand for solar power is highest in unpredictable locations with varying obstructions I wonder if you wouldn't need to spend the same amount on several silicon panels to get the same real-world output of a CIGS.
This application is where they may or may not make sense (setting aside cost for now). My presumption is that traditional rigid panels would win out on the whole, in most scenarios, because the CIGS panels are at a disadvantage due to efficiency, that they would have to make up for. But if you tend to camp in conditions that are predominantly super unpredictable mix of shade and sun at the same time, there might be advantages to these panels.

Using the stats from the link you gave of 11% compared to a 22% top of the line Rec Solar panel with half cut cells. If on a theoretical camper roof you could fit 1000W of rigid panels, you could theoretically fit 500W of CIGS panels (half the efficiency so twice the area). So to break even or come out ahead, the CIGS panels would need to perform remarkable well in partial shade combined with the traditional panels performing terribly, and you would need to be in partial shade for a large proportion of your time to possibly justify them. At least that is my thinking at the moment. So the question I suppose is how much better do they do in shade in real world conditions compared with the most shade optimized rigid panels and arrangements. And a secondary question is if shade is that big a proportion of your scenario, would either (1) no solar, or (2) removable/ground mount panels with a 50 or 100ft cord make more sense than roof mounted panels of any type.

If partial shade performance was your only concern, a high efficiency rigid panel with per cell bypass diodes might be the best option (if it existed). I am intrigued by the idea of more bypass diodes, not necessarily one per cell.
 
i’m testing 320W CIGS panels (4x80) in backyard and the partially shaded power production is nice. the price was not.

best deal i can find is for 50W flex CIGS panel for 80 USD : https://www.amazon.com/Flexible-Rollable-Charger-Generators-Batteries/dp/B09154L69K/ this is my favorite one just because the semi reasonable price makes it less anxiety inducing to handle.

the 50W CIGS miasole panel i have cost 1.6 USD per watt rated capacity which is kind of less than mentioned earlier in thread.

they produce power but i don’t have any long term data to share at this time. they are noticeably more resistant to shading vs the mono rigid panels i’ve used before

the inefficiency of space vs normal panels is also noticeable which discourages me from further deploying this technology. in addition to cost vs watts efficiency.

one more nice thing i’ve read little about is the resistance to power production decline in high temperature, but this aspect has not been noticeable.
 
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i’m testing 320W CIGS panels in backyard and the partially shaded power production is nice. the price was not.

best deal i can find is for 50W flex CIGS panel for 80 USD : https://www.amazon.com/Flexible-Rollable-Charger-Generators-Batteries/dp/B09154L69K/ this is my favorite one just because the semi reasonable price makes it less anxiety inducing to handle.

the 50W CIGS miasole panel i have cost 1.6 USD per watt rated capacity which is kind of less than mentioned earlier in thread.

they produce power but i don’t have any long term data to share at this time. they are noticeably more resistant to shading vs the mono rigid panels i’ve used before

the inefficiency of space vs normal panels is also noticeable which discourages me from further deploying this technology. in addition to cost vs watts efficiency.

one more nice thing i’ve read little about is the resistance to power production decline in high temperature, but this aspect has not been noticeable.
Any more specific info / testing on the partial shade performance? This is one of the most intriguing areas to me.
 
basically when setting up the first one up, had it connected 1S1P to bluesolar mppt.

with the panel in full sunlight, i selectively blocked parts of it with my hand/arm to see how much the power production went down. battery was good LFP cells that were below 3.3vpc re: charge acceptance confounder.

the 80w panels are long, so i started around the halfway point lengthwise and poked a shadow to “cut off” the two halves of the panel from uniform insolation. taking care to try out two conditions: 1) shadow completely crosses narrow way and 2) shadow only partially crosses narrow way

this was done by positioning arm to first cause small shadow then yeah. don’t have any data log from that instance, just looked at the victronconnect bluetooth app reading out the data in real-time and subjectively assessing the degree of power loss relative to original full light unshadowed condition a minute or two prior

don’t recall the specific ratios for full light, total cross shadow, partial cross shadow.

ill try to do another test in the coming week with a few examples consisting of (picture of panel to show insolation pattern)+(power produced or voltage or something)
 
Any more specific info / testing on the partial shade performance? This is one of the most intriguing areas to me.
Shade performance is also intriguing to me, but also the claims that they do better in low light/low angle situations. If power generation can start earlier in the day or maintain during overcast weather, that's a real plus.

Here's the thing - lets say (for example) that a 200w solar panel mounted on the roof would suffice to recharge my RV Trailer battery (202ah LFP) in sunny situations (we're modest power users). When I camp in overcast conditions, or our site is partially shaded, lets say a mono panel could only manage producing 80w but a CIGS could still put out 160w, then I'd actually need 400w of the mono panels on my roof comparatively to stay afloat. That 400w would be excessive during sunny conditions though - I'd also need to go for rigid panels since the flexible monos are so fragile.

Now I know these numbers are probably not reasonable - one site I saw claims CIGS would produce 10%-20% more power that a similarly rated Silicon panel - I only chose those numbers because of the easy math. The tests I'd like to see would be similar watt CIGS vs a Mono or Poly in the following conditions: Sunny (or ideal), Overcast, partially shaded, and low angle. I'd like to see how much lower wattage the silicon panel produces to know how many rigid panels I'd need to purchase to generate what the CIGS is capable of, to know how best to invest my dollars.

That flexible CIGS are more durable puts them ahead of flexible silicon panels, and that they are more capable would potentially put them ahead of rigid silicon. How far ahead would determine if they're worth the cost, although I'd MUCH prefer to have one flexible panel on my roof than several (or even one) rigid one.
 
Here is (what seems to be at first glance) a more objective comparison of different types of flexible panels than some of the marketing materials for CIGS panels.

I can't verify or vouch for any of it, but according to the comparison, it seems some of the professed advantages may not be objectively true (low/variable light performance, temperature coefficient, etc).

I do however see on Wikipedia that in lab/research conditions CIGS cells are reaching the same ballpark efficiencies as polychrystalline, but it seems that in practice, module (panel) efficiency of commercially available options is still lagging. However, if this improved, or if costs come down, or ideally both, this type of panel could be much more competitive for certain use cases (in my eyes), particularly when combined with the per cell diodes that you mentioned earlier.

edit: also I agree, I would love to see the testing you referred to above.
 
ill try to do another test in the coming week with a few examples consisting of (picture of panel to show insolation pattern)+(power produced or voltage or something)
Thanks for offering to test, @curiouscarbon - I look forward to whatever data you're able to find.

It's not that I'm sold on CIGS, I have just come across so many posts where folks like me are hesitant to drill rigid panels to their RVs and are researching flexible panels, only to determine that they're not reliable. We all want the best bang for our buck and I think a good quality flexible panel with CIGS features would be very valuable to RVers. I did find this CIGS discussion here where they instead suggest "shingled" semi-flexible panels - this also looks very intriguing. Coulee makes a flexible monocrystalline panel that has similar shading and durability claims to CIGS...
 
One thing that I think is worth differentiating (at least for the theory side, in practice it may not make a practical difference). Is the solar cell/module technology versus design decisions on top of that.

If I understand correctly the CIGS panels you have shown, achieve or claim to achieve good partial shade performance, through using an equal number of bypass diodes to cells, is that correct? If so its worth noting that that is just a design decision (cost/benefit) that could be implemented with any tech, not a feature of the CIGS modules themselves (unless there is a reason its a more viable design choice with CIGS).

Of course in practice, if CIGS panels are the only ones employing per cell bypass diodes, it doesnt much matter to the consumer why. But the distinction is still relevant in terms of understanding the pros/cons of the panel type itself. As far as I know, cost/benefit is one of the main reasons most manufacturers stick to between 3 and 6 'zones' (3 bypass diodes). The per cell bypass diodes could be accounting for some of the additional cost of CIGS panels, or there could be some reasons that it is more affordable to use per cell bypass diodes with CIGS panels. Do you have a better understanding of this? or more info? I would be curious to learn more.
 
Here is (what seems to be at first glance) a more objective comparison of different types of flexible panels than some of the marketing materials for CIGS panels..
Interesting info in that link, really makes amorphous silicon looks like a better option - It can be hard to parse out facts from marketing claims though (case in point, here is Ascent Solar with a similar chart that gives CIGS the edge over a-Si).

One thing that I think is worth differentiating (at least for the theory side, in practice it may not make a practical difference). Is the solar cell/module technology versus design decisions on top of that.

If I understand correctly the CIGS panels you have shown, achieve or claim to achieve good partial shade performance, through using an equal number of bypass diodes to cells, is that correct? If so its worth noting that that is just a design decision (cost/benefit) that could be implemented with any tech, not a feature of the CIGS modules themselves (unless there is a reason its a more viable design choice with CIGS).
So the one company I linked to in my first post advertises having one bypass diode per cell. Other brands I researched don't indicate their use of bypass diodes, but speak of the shade tolerance as a characteristic of CIGS. On the Ascent Solar page I linked above there is a pic showing how power can route around damage in the cell as opposed to killing the output of the cell for 'other solar technology'. I imagine it handles shading in a similar way - the usable power is bypassed inherently.
 
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I bought 6 100w hanergy/global solar cigs panels. I made a Longshot offer on ebay, and got them for 50 cents a watt. I haven't gotten around to mounting them. But I have high, perhaps misplaced hopes .
 
Here is a more specific article showing a greater reduction in output per year for CIGS :


To quote from the article:

The rated power output of solar panels typically degrades at about 0.5%/year. However, thin-film solar panels (a-Si, CdTe and CIGS) degrades faster than panels that are based on mono- and polycrystalline solar panels lifespan.

But I have no application for flexible panels myself, just trying to add to the discussion.

If you have the budget and an application calling for flexible panels it’s a good choice for sure.
Got a 10 year old CGIS Array with regular glass panels. By Würth Solar https://www.techinsights.com/products/ppr-0905-902

The manufacturer bankrupted and sold of their solar manufacturing.

The best productive year was 8. At least no noticeable drop in output on the system level yet.
 
Got a 10 year old CGIS Array with regular glass panels. By Würth Solar https://www.techinsights.com/products/ppr-0905-902

The manufacturer bankrupted and sold of their solar manufacturing.

The best productive year was 8. At least no noticeable drop in output on the system level yet.

Thanks for this eXodus. Any information you could provide in regards to benefits vs crystalline panels? Could you speak to any of the points I mentioned earlier?
The tests I'd like to see would be similar watt CIGS vs a Mono or Poly in the following conditions: Sunny (or ideal), Overcast, partially shaded, and low angle. I'd like to see how much lower wattage the silicon panel produces to know how many rigid panels I'd need to purchase to generate what the CIGS is capable of, to know how best to invest my dollars.
 
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