Which panels and inverter.....

[Ian-LS]

I'm not sure where you are getting 80% after 15 years from as all panel manufacturers have performance at 80% after 25 years so 0.8% reduction per year. A panel manufacturer (say solar world) who have 0.7% guarantee per year would mean a system producing 3600 kWh in year one would produce 3,040 kWh after 25 years at 0.7% reduction and about 2940 kWh at 0.8% reduction after 20 years.

You'll make about 100 kWh more per year using a Steca Grid inverter. Stuff like high temperature and low light performance of panels are just if not more important than 25 year performance warranty guarantees

 

[logical]

A typical panel like the Hyundai has a guarantee that states 10 years for 90 % of warranted min. power, 25 years for 80 % of warranted min. power. So for the first 10 years output should not drop below 10% of rated output and then for the next 15 years it should not drop below 80%. A total of 25 years of performance guarantee. If you draw a graph of the two guarantees ,% against time, the area above the stepped guarantee is the exta guaranteed performance you will get. I took 15 years as a median point to illustrate the performance difference. A number of manufacturers are now offering a linear guarantee whilst others are not. You can draw your own conclusions.

You are right about the inverter. Correct inverter choice is important and I don't just mean matching the electrical performance. Lifetime performance and efficiency are key. Some of the lower cost inverters are lower cost because they use lower grade components. Components that are operating on the threshold ratings will not last as long as a component that is comfortably in spec. Design and build quality is another. Where compromises and short cuts have been made in design they will show themselvesover time, I am a big fan of the Steca inverter unfortunately they seem not have caught on in the same way as SMA Fronius and PowerOne

 

[Worcester]

The big problem with output performace gaurantees, is that 99 times out of 100 they are not worth the paper they are written on. (linear or stepped)

About the only people that can afford to properly monitor and test the actual outputs as they wil have to be done under STC are the megawatt ground installations, so to Mr and Mrs Jo Bloggs, they make good sales spiel, and impossible to check....

Look at the terms too, if you aren't one of the megawatt sites, I doubt you'll ever be able to claim....

 

[logical]

Once installed it becomes very hard to monitor individual panel performance (although fitting micro inverters is a solution). There are so many other factors that will impact performance. I think that over the next few years a number of issues will become important. Already in the States there are an increasing number of panels suffering from delamination. UV endurance is essential for the continued performance of the panel. IEC standard only requires 15kWh per square metre, however the average UV radiation for central europe is 50 kWh per square metre. I dare say there will be panels suffering from UV degredation only after a few years.
Quality costs and lower cost modules are unlikely to have had peel tests, electroluminescence hotspot tests, enhanced mechanical and inclined plane load tests even hemispheric lighting tests. These are all to all to improve life performance. After all these panels are going to be on the roof pumping out power for the next 25 years and hopefully a lot longer. That is why it is worth paying a few extra pence per watt now.

I agree most guarantees are not worth the paper they are written on, but some are. The main purpose of these guarantees is to give peace of mind, but that can only be given if there is substance to back the claims. A printed pdf datasheet and a copy of third party insurance is not enough. A detailed description of the quality assurance procedures and performance criteria is. Guarantees should just form part of a complete package of information. The consumer is looking to the installer as the one that knows these things and will help them come to the right decision. Unfortunately in my experience not all installers are like that. Maybe it because in many cases they are asking the wrong person

 

[Worcester]

AAgh, the preserve of the shiny suit brigade
Sorry @logical Joe Bloggs public isn't going to do that kind of reaearch, and I'm not usre I'd believe the maunfacturers claims anyway. There again some people tell me I'm a cyinic when it comes to those claims.
Only an independant set of verified tests in some kind of published comparison database (e.g. photon report) will carry any provenance

 

[logical]

Worcester I know what you mean. Having been a procurement specialist in the electronics industry for many years I have had my fill of the shiny suits and I think I can cut through most of the BS. I am not surprised at your cynicism, some of the things I have heard claim does beggar belief at times and cynicism is a form of protection but it can blind you to something that is of value. I have already mentioned the Photon tests and it is a good place to start. If a company is making performance claims their product should be in or near the top 10 consistently year after year. Some panels have a blinding year and then fall back down the performance list. Some panels will be in their 5th year of the run and some will be in their first. The Photon test gives some great information but it is open to interpretation.
Of course Joe Bloggs public is not going to do the proper research even if they think they do. There is so much misinformation and un-informed opinion in amongst all the good stuff. Even the most switched on customer would struggle. That is why the installer (not the shiny suit) is there to give value information to help the customer. They are the ones with hands on experience. They are the ones that should be doing the research. They are the ones that should be looking at the build quality of the panel, the quality of junction box, the quality of materials used. It is a matter of using ones eyes and judgement and asking the right questions of the manufacturer. If you can go on a factory visit go and see for yourself and understand what some manufacturers are doing and why. There are some large scale manufacturers who would not stand up to this scrutiny.
I feel for the OP as they were asking for a little guidance as to panel and inverter choice, they may or may not have been given advice by the installer they may have just been looking for re assurance. My point was go for quality every time. Now it is down to me to supply the installers with the tools that can help prove the quality of the panel. Something that will get through to the most battle hardened and industry bashed cynics.

 

[midsummerenergy]

Hi Pavlaba, check out this website

Hi Pavlaba,
I recommend to have a look at our website, Midsummer Energy - TRADE AREA and try to design your own system in our own program, http://easy-pv.co.uk/ , it's very easy to do it, you just need to follow a few steps:

1-. Draw your roof.
2-. Select and lay out the panels on the room.
3-. The frame will be designed automatically in the next step.
4-. Then you just have to add the Ac and DC isolators, the number of them are already calculated by the program.
5-. Select your control unit (Landis recommended)
6-. And monitoring unit if necessary.

Once you accept the design you'll get a quotation from Midsummer energy in a couple of days.

Hope to hear from you.

Best wishes.

Pablo.
Midsummer Energy.