Energy Yield from panels

[TRBob]

In late December 2010 we had 3.74 kW capacity installed on our south facing roofs, to date it has generated just over 1700 kWh of electricity. One thing that concerns me is that on sunny days around midday it has only reached about 2.7 kW, is this normal, surely shouldn't they be kicking out the full 3.74 kW in these conditions?

 

[malcolmsanford]

Short answer will always be not necessarily. With a PV system you are always in the hands of variables such as weather conditions for Radiance.

You could also factor in maintenance of the panels as well, after 7 months on the roof they be in need of a clean.

 

[TRBob]

Whats the best stuff to clean them with? I've heard that washing up liquid is a no-no as it can break down the protective layer.

I think the angle they are on the roof is a factor, as in June the Sun was a bit high, but now its getting lower again and its rays becoming more perpendicular to the panels, it seems to be generating more.

 

[dansk]

Hi,

What panels are they? make and model, number of? and what make and model inverter have you got? we can check through the config if you like as there may be a chance the inverter is holding it back a tad - or at least we can confirm its a good match.

 

[malcolmsanford]

Hi,

What panels are they? make and model, number of? and what make and model inverter have you got? we can check through the config if you like as there may be a chance the inverter is holding it back a tad - or at least we can confirm its a good match.

There is kind help from someone that knows what he is actually taking about rather than my waffle.

 

[dansk]

No one said i know what im talking about ;-)

 

[malcolmsanford]

No one said i know what im talking about ;-)

Ahhhhhhhhhhh and you hide it so well

 

[dansk]

lol

 

[amigo4lavida]

I have wondered whether a rural array would be more effective that that in a urban area or city (alongside a busy road) were there are more particulates etc. in the atmosphere.

A4l

 

[dansk]

I have wondered whether a rural array would be more effective that that in a urban area or city (alongside a busy road) were there are more particulates etc. in the atmosphere.

A4l

Possibley, due to irradiance, and cell tempreture could be cooler in rural areas which helps with generation, but i'd be surprised if you had two systems identical one rural and one urban if it actualy made that much difference.

 

[SolarCity]

1700 kWh of power doesn't sound too bad. Whereabouts in the country are you?

Incidentally, I have seen an 2.5kWp install which, for one day only, struggled to get above 2.1kW - it was one of the clearest days we have had this year and I'm still baffled by it.

Have a check on your system and make sure it's not covered in bird mess.

If the problem continues then it wouldn't hurt to give your installer a ring and get him to check it out.

 

[TRBob]

We're in South Yorkshire, on a farm, so they do get quite dusty, although had some rain lately which has cleaned them a bit. Not too much bird mess on them.

In reply to Dansk, the panels are Solar World, there are 18, not sure which models, i've emailed our installer to ask, not heard back yet. The inverter is a Solar World Sunny Boy SB 4000TL-20.

 

[dansk]

ok, come back once you know the model of the panels, i have taken a quick look but couldnt find any panels that divide into 3740w to give 18 panels.

 

[SRE]

I'd suggest you get yuour installer back - those figures are way too low. We're further North than you, installed 3.96 kwp on an ESE facing roof in a rural area at the end of October. I don't think we'd generated 100 kwh by December and we've just hit 2500 kwh this morning. Even taking into account the November generation that's 50% more than you've got. We get up to 4kw ocassionally but more often on a decent sunny day @ about 20 degress we'll hit 28kwh in the day and between 0 an 3.6 ish kwh at any one time. Our display is showing 1.8kw as I write this ...

Most of our installations are rural - we have loads of problems with over voltage and inverters cutting out during peak periods, you should get your installer to check that first - you can check yourself by looking at the inverter on a sunny day usually between 1 and 3, maybe a bit sooner as you're a bit further South than us.

 

[Worcester]

@TRBob,

Your installer should have given you a handover pack with all the details of the panels and inverters etc including their warranties, also the MCS certificate that he gave you will also have the panels listed on it, have a quick look there.