Solar PV Ordered!

zeupater

LydiaJ wrote: »

One of my friends over on the house prices board found this for me. It gives actual annual output from a collection of panels that I believe were nominally the same power rating. With a 10% difference between the max and min, it's significant but not overwhelmingly vital.

Hi

And what they don't consider in tests such as this are the standard manufacturing performance tolerances ..... are they comparing all panels selected & supplied at nominal/top/bottom tolerance, or representative of what is a supply average, or ........

When I looked at a system I spent a long time looking into relative performance between manufacturers and paid particular interest to the tests referenced above. In the end I considered that a number of panels were compared against others which were not in current supply (& hadn't been for a considerable time), also, there were certain manufacturers who had beneficial test results on one particular panel test/review, which were/are referenced in their marketing across their entire range of pv technologies and products.

Regarding what you are being told on the performance of certain panels in higher temperatures, this is supported by the technical data for the panels .... however, what needs to be considered is that performance at very high temperatures is less likely in the UK than other locations. The very same manufacturer mentioned makes an interesting claim on their panel performance in their marketing literature, however, checking the smallprint exposes this claim to be for a comparison against another panel on one particular day in one particular location without any information supplied on the relative panel tolerances or any other data/description of the tests, or even the panel technology or even age of the panel with which the comparison was made .... to me that provides no form of proof and should therefore be discounted.

In the course of investigation you will be told that this panel is x% better than that panel, or the performance of a certain panel will degrade slower than another over time and that's what the technical details and guarantees will support ....... what you will not necessarily be told is that the panel performance tolerances are far more important and could easily eclipse anything else. Some manufacturers have a +10%/-5% tolerance band .... if you're lucky you'll get a panel pack at top tolerance, if not you wont, so ask the installer what the average test performance of the panels which they will supply will be .... you'll probably get a little babble, but you'll not get a straight answer because they will not know and certainly will not be able to guarantee anything higher than nominal performance. Don't you just love marketing people & salesmen.

If you want to support UK manufacturing in any form your choice of panels is Sharp or Romag, if you have a small roof & require to maximise the generation capacity of the system look at the Sanyo hybrid panels you referenced, there are lots of good (mainly German) european panels, then there are decent panels from China such as Suntech & Yingli, then there are hundreds of cheaper manufacturers which will likely vanish over the medium term ..... just make sure that you actually see panels before you make a final decision as some are far better looking at a distance than others (if that's an issue).

HTH
Z

Cardew

Super post zeupater - tends to confirm my gut feeling in post #101 above!!

celerity

I have Moser Baer panels which never seem to appear in these types of lists, which could be worrying for me...
Having said that, they are performing well above expectations at the moment, so currently I'm happy.

/\dam

LydiaJ

Thanks zeupater for such a comprehensive explanation. And thanks everyone. Starting from a position of knowing almost nothing a couple of weeks ago, I'm learning loads, which is exactly what I came on this board for. It's much appreciated. :T

mickyduck

Just ordered 3.9 system, quite excited as not too many bad stories on any of the forums! The decision about what to buy is quite tricky (or I thought it was) it is VERY difficult to compare systems V Price. I had 6 people come to sell me a system. To be fair all except one seemed honest upfront giving similar quotes. One visit was very double glazing salesman, sign and buy now, limited time offer etc etc Quote was almost double ALL other quotes. Don't buy in haste...............

Salty67

Hi. New to forum, so hope this is in right place. Also new to p.v, so hope what follows makes sense.
Have just had a matching quote for R.E.C. (poly) or Sharp (mono) (£11, 500 for 3.675kW) or Siliken (poly) for £11, 750. No real pressure at all from salesman on which to choose, though expressed a slight preference for R.E.C. But I've only heard of Sharp, and I thought mono was meant to be a better choice than poly. Can anyone clarify?
Many thanks.

zeupater

Salty67 wrote: »

Hi. New to forum, so hope this is in right place. Also new to p.v, so hope what follows makes sense.
Have just had a matching quote for R.E.C. (poly) or Sharp (mono) (£11, 500 for 3.675kW) or Siliken (poly) for £11, 750. No real pressure at all from salesman on which to choose, though expressed a slight preference for R.E.C. But I've only heard of Sharp, and I thought mono was meant to be a better choice than poly. Can anyone clarify?
Many thanks.

Hi

I have monocrystalline, read into that what you will ....... if you trust the performance guarantee on the panels you choose, then you must trust that the manufacturer will be around to honour their pledge ....... it's a simple choice if you are willing to make it.

HTH
Z

noncom_2

From my (limited) understanding, monocrystalline panels have higher efficiency ie they produce more electricity per square metre of panel.

All this equates to in practice is that a 4kWp system of monocrystalline panels will be a bit smaller than a 4kWp system of polycrystalline panels. Their outputs will be similar otherwise. (Of course, different panels will have different "transfer curves", ie the actual amount that they produce at a given light level may be different, but you really have to go into huge depth of data and modelling to see what the practical effect of this would be in your location).

If your roofspace is very limited, such that you can't fit a 4kWp system of poly- panels on it, it may be worth paying a little extra for mono- panels so that you can maximise the peak production capacity of your system.

HTH

GordonGowk

Hope this is an ok place to ask this?

My 4kW PV was installed 2 months ago and doing great. I'm very happy with the system and how much energy it's created. It just seems a shame that the sunny boy inverter clips the output at 3kW (sometimes 3.15kW) - it never goes above that. I have read about larger inverters needing more energy to power-up and smaller ones make more energy on dull days (which is far more often than peak output), so is the clipping ok at 25%? It would just be a shame to find out in years to come that a simple adjustment could have given me a far better output.

Also, thanks for some very interesting reading in this forum.

Celestine_2

Just ordered my 2k system and should be installed in a few weeks. Does anyone know where i can get a little spreadsheet or something similar so I can recored my energy consumption before and after installation?

Any help would be much appreciated.

Thanks.