Solar Panel Guide Discussion

zeupater

Gizmosmum wrote: »

PVSOL says:

16 panels, due South, 30 degree pitch.

Sunnyboy 3800 on 2 strings:

Schott 240p - 3251kwh
Sharp NU240 R - 3036kwh

Fronius 3.6TL on 1 string

Schott 240p - 3355kwh
Sharp NU240R - 3161 kwh

I'd say that the panels were comparable, actually on paper you'd think that the Sharp would be better because they're mono rather than poly but apparently Schott poly are better in our cloudier conditions. Both have positive tolerances on power of 0-5%. Schott warranty is better for performance and product.

We have Sharp but the I know the guys I work with are tearing their hair out trying to get decent quality, robust panels from Sharp with consistent supply - apparently it's not happening yet.

I bought Sharp because I wanted to do my bit for the economy but I was a bit peed off that the installer had to ship them over from Germany!! It's a while ago now so maybe it isn't happening but at the time they were getting the components from China, making the panels in Wrexham and shipping them to Germany for testing. Still generating some work in Wrexham which is important but not particularly cheap or green, there are loads oa manufacturers out there who provide a more green, ethical panel - I guess it just depends on where your loyalty lies.

Hi

Okay .... SMA SunnyDesign figures ... same setup S/30Deg Roof/SB3800/2Strings of 8 panels .... based on central England (Birmingham)

Schott Poly 240 ... 3299.9kWh/year
Sharp NUE240 ... 3270.9kWh/year

Therefore a margin of 0.89%, which, as previously mentioned (more than once) is a difference which can easily be eaten up by the manufacturers' tolerances, we seem to have been here before ....

zeupater wrote: »

.....
Sharp tolerances are -5%/+10%, Schott are -3%/+3% and Suntech are -0%/+5%, therefore the median expectation against nominal rating is +2.5% for Sharp & Suntech and 0% for Schott .... then again, any of the panel packs supplied could be top tolerance , or bottom .....

Z

Where other Schott panel specs show a performance tolerance of -3%/+3%, their Poly240 datasheet (http://www.schottsolar.com/global/products/photovoltaics/schott-poly-240/) states a performance tolerance of -0W/+5W (not %), so a median of +2.5W, so taking the median on the tolerance bands you could expect ....
Schott Poly 240 ... 3302.4kWh/year
Sharp NUE240 ... 3352.7kWh/year ....

However, a more realistic viewpoint would be to discount the comparison of the Schott 240W panel with the Sharp NU240 because most Sharp installs would be using NU245 or NU250 panels so on the same roofspace the Sharp 245 panels suddenly move to 3345.6kWh/year, which with median tolerance expectation would be 3429.2kWh.y, so suddenly a typical supply Sharp system could be said to be capable of delivering 3.8% more power (3429.2/3302.4) with the NU250 panels performing even better ... some could be lucky to have a very good panel pack according to the flashtest data, well above median tolerance and could therefore far outstrip these figures , others may not ...

As can be seen from the analysis above marginal differences between panel ratings are not worth worrying about, and absolutely no supplier would provide a cast-iron guarantee on a 240W panel pack supplied by Sharp or Schott would perform better than the other .... however, I do find it interesting that the 240W Schott panel which seems to be the largest in their Poly range is being compared with a 240W Sharp panel which is not a unit which installers typically fit ....

Note .. all analysis above conducted with SMA Sunnydesign 2.00.4R software available for free download here .... http://www.sma.de/en/service/downloads.html and I agree that the specs on paper should provide very similar results, that's why I suspect that there is a problem with the PVSOL database .....

HTH
Z

Gizmosmum_2

zeupater wrote: »

Hi

Okay .... SMA SunnyDesign figures ... same setup S/30Deg Roof/SB3800/2Strings of 8 panels .... based on central England (Birmingham)

Schott Poly 240 ... 3299.9kWh/year
Sharp NUE240 ... 3270.9kWh/year

Therefore a margin of 0.89%, which, as previously mentioned (more than once) is a difference which can easily be eaten up by the manufacturers' tolerances, we seem to have been here before ....



Where other Schott panel specs show a performance tolerance of -3%/+3%, their Poly240 datasheet (http://www.schottsolar.com/global/products/photovoltaics/schott-poly-240/) states a performance tolerance of -0W/+5W (not %), so a median of +2.5W, so taking the median on the tolerance bands you could expect ....
Schott Poly 240 ... 3302.4kWh/year
Sharp NUE240 ... 3352.7kWh/year ....

However, a more realistic viewpoint would be to discount the comparison of the Schott 240W panel with the Sharp NU240 because most Sharp installs would be using NU245 or NU250 panels so on the same roofspace the Sharp 245 panels suddenly move to 3345.6kWh/year, which with median tolerance expectation would be 3429.2kWh.y, so suddenly a typical supply Sharp system could be said to be capable of delivering 3.8% more power (3429.2/3302.4) with the NU250 panels performing even better ... some could be lucky to have a very good panel pack according to the flashtest data, well above median tolerance and could therefore far outstrip these figures , others may not ...

As can be seen from the analysis above marginal differences between panel ratings are not worth worrying about, and absolutely no supplier would provide a cast-iron guarantee on a 240W panel pack supplied by Sharp or Schott would perform better than the other .... however, I do find it interesting that the 240W Schott panel which seems to be the largest in their Poly range is being compared with a 240W Sharp panel which is not a unit which installers typically fit ....

Note .. all analysis above conducted with SMA Sunnydesign 2.00.4R software available for free download here .... http://www.sma.de/en/service/downloads.html and I agree that the specs on paper should provide very similar results, that's why I suspect that there is a problem with the PVSOL database .....

HTH
Z

Not quite sure about the logic of comparing 240 with 245 or 250w bit like apples and pears. I thought the argument was that Sharp were better than Schott in which case you need to compare like with like The NUe's are older models NUR versions are the latest, the third this year I believe.

No argument about difference in product or performance guarantees Schott outstrip Sharp by far, but I'm guessing that Sharp won't be very far behind with improving theirs. Most manufacturers are rushing 250w panels to the market no doubt Schott will be the same.

If Pvsol is wrong the installers all over the World will have a problem - it's the universal software tool of choice and has the benefit of matching many different panels and inverters not just SMA.

I think we'll have to agree that there are many permutations and options and that one is not necessarily better than the other for all situations which is why you should go to a local firm who are more interested in providing something which meets your needs not theirs.

keith_r59

Gizmosmum wrote: »

I think we'll have to agree that there are many permutations and options and that one is not necessarily better than the other for all situations which is why you should go to a local firm who are more interested in providing something which meets your needs not theirs.

You make it sound like local installers will source any make/model of panel you want. I doubt that very much and as the output differences are so small (as Zeupeter has consistently shown) I don't think it is the big deal you seem to be making it out to be.

I have Sharp panels on my roof and I am very happy with their performance as the solar generation has out performed both the installers and PVGIS estimates. Would I have generated even more solar energy with a different make/model? I will never know, but I don't think I will be losing any sleep over it.

zeupater

Gizmosmum wrote: »

Not quite sure about the logic of comparing 240 with 245 or 250w bit like apples and pears.....

Hi

I thought it would be quite obvious to everone that a direct comparison between 240W models was made and that the Sharp 245W & 250W panels were raised because these are the panels which seem be more relevant to most installs, it's just that Schott don't have anything above 240W in the relevant range that anyone would push for a direct comparison .... anyone wanting to maximise their array size in the 4kWp FiT banding and confined to maximum of 240W panels within a particular range would be restricted to a 3.84kWp system, whilst 245W would get them a 3.92kWp system and 250W would give a 4.00kWp system .... and that's exactly why these options were raised ....

Now, for those who are currently unaware of the technical difference between polycrystalline and monocrystalline and why polycrystalline is/should be an inferior/cheaper product ....
http://en.wikipedia.org/wiki/Monocrystalline_silicon
http://en.wikipedia.org/wiki/Polycrystalline_silicon

... note the reference to grain boundaries, so here's what that means ... http://en.wikipedia.org/wiki/Grain_boundaries, also note that the polycrystalline grain size is huge.

There's nothing wrong with polycrystalline modules, but for the reasons above I personally prefer a single crystal .... but if we're talking 'apples & pears' it should be remembered that both apples & pears come in different sizes, it's the makeup of the apple which makes it different to a pear, just as monocrystalline and multicrystalline(polycrystalline) wafers are different ....

HTH
Z

pcolmer

I've been getting a number of quotes for a roof-based system and I was getting close to making a decision when I read this an article on The Register entitled "Does Cameron dare ditch poor-bashing green energy?". I can't link to it, unfortunately, but the most important paragraph would seem to be:

The Telegraph has obtained a policy document, dated July, that seems to suggest that the government is considering a walk away from the most expensive renewables. Two No 10 advisers challenge the Department of Energy and Climate Change's utopian cost predictions, and say energy bills will be much bigger than we've been told.

My concern - and question, really - is what happens if I do go ahead with an installation on the basis of the FIT giving me a good return on my money, and the government then does a U-turn and drops the whole idea of the FIT?

Is it really guaranteed for 25 years or could they land everyone who has invested in the technology in a whole heap of pain by no longer paying out?

Philip

zeupater

Gizmosmum wrote: »

..... I thought the argument was that Sharp were better than Schott ....

Hi

This is incorrect, the discussion is to show that in terms of performance, Schott are unlikely to be any different to, or better than Sharp and that noone would guarantee that a pack of either would perform better than the other, I doubt that, due to the effect of tolerances, any installer would guarantee that an equivalent kWp rated pack from any quality manufacturer would outperform any other over a decent period of time, and that would include the Sanyo HIT panels ..... and that's all I'm proposing ....

If your client is so confident that the Schott polycrystalline panels are so good and would outperform my mono units by anywhere near 9.6% (3355/3061) on a kWp v kWp basis then I would be confident and willing to pose a challenge .... As I have the space, I could put a second 4kWp system besides my current one as a new FiT install (new year), along with the same model inverter fitted too ... if the new install outperforms my current one over 12 months I'd pay for it, if not the installer (or Schott) can provide the installation for free and I'd even pay the additional DNO costs and a reasonable additional amount for matching my current mounting system.... I'm sure that they'll soon either find that the PVSOL results are incorrect or that their product confidence isn't quite what it's claimed to be ...

It's not just PVSOL which have issues with their database, I've seen problems with a particular SunTech module data in an old version of SunnyDesign and there was also a discussion on another make on this forum a few weeks/months ago regarding the database being incorrect, comparing the database to the specsheet we even found the reason ....

The issues really resolves down to your client. I take it that he/she/they currently provide Schott polycrystalline panels and do so mainly because of margin, are probably having serious competition issues and are therefore using any possible means to sell product, if not they'll jump at my challenge and all of the positive coverage it would produce for them ....

Anyway, I'm starting to get a little bored with this marketing hype, it has absolutely no positivity in promoting the adoption of pv technology to anyone who is interested. Of course, Schott is a good make, but singling out a company who actually manufacture product in the UK with so much directed negativity is a little frustrating, especially as much of the information is likely to be factually incorrect or anecdotal.

HTH
Z

grahamc2003

pcolmer wrote: »

I've been getting a number of quotes for a roof-based system and I was getting close to making a decision when I read this an article on The Register entitled "Does Cameron dare ditch poor-bashing green energy?". I can't link to it, unfortunately, but the most important paragraph would seem to be:



My concern - and question, really - is what happens if I do go ahead with an installation on the basis of the FIT giving me a good return on my money, and the government then does a U-turn and drops the whole idea of the FIT?

Is it really guaranteed for 25 years or could they land everyone who has invested in the technology in a whole heap of pain by no longer paying out?

Philip

Everyone says it's guaranteed by the government, but in reality, that guarantee is worth much less than a guarantee on, eg, a tv from Tescos.

A guarantee doesn't mean anything more, imv, than if there is non-performance (i.e. the fits are withdrawn or the tv breaks down), then you can ultimately sue and get back the position you would have had if the contract did perform.

With Tescos, there's little doubt you could sue them (if they didn't honour the terms of the guarantee), but with the government, they can simply change the law for fits to effectively make it so they can't be sued. Basically, we elect them to rule the roost, so in reality, they can do almost anything at all if enough MPs agree.

fwiw, I doubt the government would want to leave people in the lurch by instantly removing all the fits, but I think it's very likely that the very generous nature of the fits will be scaled back (beyond the planned scaleback). Say by removing the index linking - someting like that wouldn't surprise me.

I don't really see why the fits shouldn't be scaled back anyhow - they are over genrous imv, and plenty of other less generous benefits are being scaled back or simply scrapped, anyhow, eg ema, child benefit and I'm sure much more of the previous governments generosity with our money will be cut back.

zeupater

pcolmer wrote: »

I've been getting a number of quotes for a roof-based system and I was getting close to making a decision when I read this an article on The Register entitled "Does Cameron dare ditch poor-bashing green energy?". I can't link to it, unfortunately, but the most important paragraph would seem to be:



My concern - and question, really - is what happens if I do go ahead with an installation on the basis of the FIT giving me a good return on my money, and the government then does a U-turn and drops the whole idea of the FIT?

Is it really guaranteed for 25 years or could they land everyone who has invested in the technology in a whole heap of pain by no longer paying out?

Philip

Hi

Welcome to the forum ...

This has been discussed a few times as it raised it's head in the press every few months. Effectively, there is no guarantee on anything if the government change the rules retrospectively, but there would certainly be a case for conducting a number of reviews or even some court cases and knowing how long these things take I would guess that my system would be well on the way to paying for itself before the scheme was stopped (I hope ).

It's far more likely that the FiT would be addressed and the tariff paid to new entrants would be seriously reduced, possibly in line with materials spot prices movement or averaged competitive install costs. The FiT is already due for a reduction for new installations in spring next year, so I would expect that there would be a further reduction above what has been published at this point in order to avoid adding complexity to the payment mechanism. A system which cost ~£20k when the FiT payment scheme was developed now costs in the region of £12k and the original payback logic would still apply, so it would make a lot of sense to expect the 43.3p/kWh to be reduced to somewhere between 25p and 30p instead of the anticipated 8.5% reduction to 39.6p/kWh (all before index linking).

If a reduction it's not done next spring it almost certainly will be by the year after, other countries have taken this approach. Germany in particular changed their system last year but made the mistake of giving far too much notice which resulted in an installation frenzy to avoid the change deadline, and the UK gave a period of notice of change to 50kWp+ systems earlier this year which had a similar effect on large installations, so don't expect the government to signal any future change. In March this year France announced a change to their payments for larger ground mounted systems where the new rate became applicable on the day of announcement and in my opinion this is the likely model for future UK announcements

Just my guess .....

HTH
Z

Doc_N

grahamc2003 wrote: »

Everyone says it's guaranteed by the government, but in reality, that guarantee is worth much less than a guarantee on, eg, a tv from Tescos.

A guarantee doesn't mean anything more, imv, than if there is non-performance (i.e. the fits are withdrawn or the tv breaks down), then you can ultimately sue and get back the position you would have had if the contract did perform.

With Tescos, there's little doubt you could sue them (if they didn't honour the terms of the guarantee), but with the government, they can simply change the law for fits to effectively make it so they can't be sued. Basically, we elect them to rule the roost, so in reality, they can do almost anything at all if enough MPs agree.

fwiw, I doubt the government would want to leave people in the lurch by instantly removing all the fits, but I think it's very likely that the very generous nature of the fits will be scaled back (beyond the planned scaleback). Say by removing the index linking - someting like that wouldn't surprise me.

I don't really see why the fits shouldn't be scaled back anyhow - they are over genrous imv, and plenty of other less generous benefits are being scaled back or simply scrapped, anyhow, eg ema, child benefit and I'm sure much more of the previous governments generosity with our money will be cut back.

Except that the FITs aren't actually being funded by the government (that's to say - us) but by an increase in energy charges levied by the suppliers on their customers (that's to say - us).

Less likelihood of the government deciding to reneague on its promise in this situation, because it isn't having to find the money itself through taxes.

keith_r59

pcolmer wrote: »

My concern - and question, really - is what happens if I do go ahead with an installation on the basis of the FIT giving me a good return on my money, and the government then does a U-turn and drops the whole idea of the FIT?

Is it really guaranteed for 25 years or could they land everyone who has invested in the technology in a whole heap of pain by no longer paying out?

This, or a future government, could well do a U-turn and drop the whole idea of the Feed in Tariff but I think this is very unlikely for the smaller scale home-based installations.

If they do anything, I think they will reduce the FIT payments for new installations more quickly than was originally anticipated and they will probably change the index linking from RPI to CPI at some stage in the future.