Solar PV Panel comparisons

Tuttlinghorn · 23-11-2021 8:52pm #1

Hi folks

if this is duplicated elsewhere pls let me know

I am comparing quotes and installers, getting recommendations etc.

I am also trying to compare the various panels that seem to be popular in the Irish market (QCells, Longi, JA Solar, Peimar ... others ?)

I am looking at efficiency ratings as a main comparison point, then the linear performance warranty, product warranty.. vs cost.

I am wondering what other important specs to watch for and how to compare them e.g. to indicate performance in low light / typical grey Irish day?

Below is a listing that I found on a UK based solar comparison website, with a couple of items removed which didn't seem that relevant. (power, weight, size - though i guess it depends on whether the buyer is constrained by roof type/size vs quantity and weight of panels)

or even better = anyone already made a comparison chart showing the more popular models in the irish market ? !

Efficiency: Solar panel efficiency, which is expressed as a percentage, measures how much sunlight can be converted into usable electricity. Most domestic solar panels have an efficiency of 15-20%.
Power tolerance: This factor determines how much your system can deviate from its stated power (watts). This deviation can be expressed either in percentages or watts. If a 100W panel has a power tolerance of +3% / −0%, then the actual power may vary between 100-103W. If the power tolerance is +5W / −0W, then the actual output varies between 100W and 105W under real-world conditions.
Temperature coefficient: You want to know how much your panel’s efficiency will be affected by temperature rise. Temperature coefficient expresses the percentage decrease in power output per 1°C increase in temperature (after 25°C).
Product warranty: Solar panel manufacturers offer warranties on their equipment, ensuring they can last. Warranties on our list range from 10-25 years.
Performance degradation: Every solar panel will experience some kind of performance degradation over its 25-year lifespan. After the 1st year, there is usually a 2-3% decline in efficiency, and 0.2-0.7% every year after that.
Maximum wind load: You want your solar panels to withstand any kind of weather in the UK, including strong winds and hurricanes. This tolerance is tested by manufacturers and is expressed in pascals (Pa). The higher the number, the higher the wind tolerance, but most panels are certified to withstand 2,400 Pa, which is equivalent to 140 mph.

23-11-2021 9:03pm

You need to look at the cost Per KW after all that's done and see if the bigger better panels are worth the extra cost

Deagol · 23-11-2021 9:17pm

https://www.boards.ie/discussion/2058219403/solar-pv-panel-comparisons

They're ~150euro each - the cheapest part of the whole install / system. Having a 20 year warranty vs a 25 year warranty - do you really think you'll be able to prove in 20 years time when you bought them and be able to contact the supplier even if they still are in business etc? For the relatively small money involved, I would recommend not to worry about it and save yourself the headaches of comparing things. All the panels are very similar - and all you can work off are the manufacturer's claims - and do you really trust them? I went on what my supplier was happy to supply - it'll be him that has to handle the warranty claims in the short term so a decent installer will be unlikely to sell you pure junk.

If you look at the main / long threads on PV, you won't find anyone who's made specific complaints against any manufacturer for poor performance or failures. Good luck with it!

Tuttlinghorn · 23-11-2021 10:49pm

https://www.boards.ie/discussion/comment/118213346#Comment_118213346

installers have been quoting me 250 per extra panel. not the 150 you mention but with some labour and VAT, is that 250 justified ?

Deagol · 23-11-2021 10:52pm

my Price is retail material only. I’d say with Labour and mounting materials etc, €250 per isn’t bad. Always haggle though, good margins being made so they have wiggle room!

bullit_dodger · 24-11-2021 12:59am

Depends on the panel, but 150-200 is about the average. Eg.

Midsummer Renewables

Course your price of 250 does (probably) include the install? So it's probably fair 250 euros. They have to get a guy up a roof and they have to make a few quid too. Anymore than 250....then it starts to get unfairly pricey

slave1 · 24-11-2021 4:08pm

https://www.boards.ie/discussion/comment/118213795#Comment_118213795

This is reasonable, some installers have a fixed rate per panel, make sense to standardise pricing

adriant900 · 16-04-2023 3:36pm

https://www.boards.ie/discussion/comment/118213346#Comment_118213346

To reawaken this thread a few years on as I do not see a more recent one discussing comparison of panels.

Do people with experience agree with the post a few years ago that it is not worth the time comparing different panels? I find it surprising, surely there are difference in product quality?

I am comparing different panels and some claim to have much lower degradation than others e.g. Recom Lion Series which are glass/glass panels which claim that after 30 years you have 91.25%. This compares well to Longi Hi-Mo that after 25years you have 84.8%. Similar cost per KW

Is there anyway to know what product quality is? Is there anyway to know if the manufactures claims in the datasheets are accurate in the real world?

con747 · 16-04-2023 3:55pm

https://www.boards.ie/discussion/comment/120484596#Comment_120484596

As a lot of people on here say "the best panel is the cheapest panel". I agree, very little difference as long as they are Tier 1 panels. Not enough difference to be loosing sleep about.

adriant900 · 17-04-2023 2:28pm

https://www.boards.ie/discussion/comment/120484670#Comment_120484670

Would you say the same for inverter and batteries?

con747 · 17-04-2023 4:14pm

https://www.boards.ie/discussion/comment/120488003#Comment_120488003

No, totally different kettles of fish! Some are a lot better than others so you need to do your homework on both.

bullit_dodger · 17-04-2023 5:07pm

Yeah, I'd agree with con747 there.

I would say though that they generally fall into a couple of "buckets". First of all, they all do exactly what they say on the tin. Inverters and Batteries convert and store power and your kettle has no clue if the power comes from a Puredrive battery as opposed to a Telsa powerwall. Some will however have higher discharge/charge rates, others custom proprietary hardware (like Huawei inverters only liking to work with Huawei batteries etc)

Others again will have better/worse telemetry and remote accessibility. That may influence your decision a lot, or you might not care in the slightest

On the plus side - there are few... if no lemons out there to avoid like the plague. Generally everything you can get on the market with the various suppliers are solid enough.

adriant900 · 18-04-2023 7:39am

https://www.boards.ie/discussion/comment/120488400#Comment_120488400

Thank you for your advice, I appreciate it, is there is list to rank different inverters with pros and cons? When I google it the sites I find have a smell of marketing off them.

To clarify on the panel comparison before we move on, on face value it seems to me that there are good differences in the degradation of panels after 25 to 30 years. Is the reason you say there is no need to give it much thought that we cant believe the manufactures claims or something else that I am missing?

graememk · 18-04-2023 9:38am

Very hard to compare inverters, they all will work well and most people won't know any different.

A big one that some of us have come across is Solis and the battery charge/discharge rate, especially with people with big batteries where it can only do 100 amps for 15 minutes whereas the sofar hybrids, sunsynk etc can hold it steady.

On a small battery it doesn't really matter though.

Also 25-30 yrs is a long way away. And is the numbers really that different?

They won't be worthless, people who have plenty of space will always be on the lookout for "cheap" panels

DC999 · 18-04-2023 12:15pm

https://www.boards.ie/discussion/comment/120490317#Comment_120490317

I fell into the 'analysis paralysis' when getting quotes. What if panels X drop 3% over their life V 5% of panels X. In the end I realised if I could fit even 1 more panel, there is no difference. Which inverters are superior. I've no battery so any inverter is the same to me. If the inverter fails, I'll chase the warranty to replace it.

And we've no way to know what the actual panel output will be in 25 years. Some panels suggest they are better in low light levels, same with inverters. Can you tell are they doing what they promise, no? But I know there is nothing else in our house (bar walls and roof) that will last 25 years. I'm live nearly a year now.

con747 · 18-04-2023 4:34pm

https://www.boards.ie/discussion/comment/120490317#Comment_120490317

The advice from the 2 posters above is good advice.

Solar PV Panel comparisons

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