PV output on a dull day, "low light" yields

[zapthis]

system commissioned late evening on the 6th 20 bosch m48 195 panels 3.9kw with fronius 3.6tl inverter
yesterday 12.6kw today only 0.8kw lucky to get over 40w today before it switched itself of when it got below 10w

it can only get worse for the next 6 weeks i feel

 

[TrickyDicky101]

Hi Alan

I have had two poor days - 700Wh today and 500Wh yesterday. My voltage and power readings have been very similar to yours (no surprises due to the similarities between our systems). I find that unless there is some form of direct sunlight, the panels really don't generate much at all. This very much in contrast to what most of the salesmen claimed when they were quoting!

I'm waiting for some very clear sunny days to see if my generation meets my expectations.

Richard

 

[Solluva]

The salesmen can’t be accused of lying ‘They even produce electricity when the sun is not shining’ But they never tell you by what proportion output drops when the sun goes in.

16 x 240kWp REC. Lyme Regis.
Sunday 6th Dawn to Dusk Sunshine: 14.5kWh
Monday 7th Overcast : 0.8kWh
Tuesday 8th Overcast : 0.6kWh

It is very interesting that the weather forecasts on 6th and 7th were identical, cloud with sunny periods. 6th turned out to be sunny with no cloud and 7th cloud with no sun. What you may call an each way bet.

aquinas_quark1 you may like to try what I do to compare outputs of local installations. Go to Naturalwatt | Solar PV Installers, Wind Turbines & Solar Thermal and click on ‘Installation Map’. You will see that there are half a dozen sites from Bournemouth to Weymouth to Sherborne. To compare any of these with your array divide the outputs by the size of the installations.

 

[kate.harrison1]

Just to concur with all of your findings, my generation figure for today was 0.444Kw and yesterday, 0.560Kw. Mind you, it has been so dark and drizzly, you practically need a torch to venture out in the day. We mustn't forget that the days are still getting shorter too to add to the generaly dull/dark conditions so days like today are possibly close to as bad as it gets.

2 strings of 8 Sanyo 240HDE4 e/w plus SMA 4000TL

 

[Aquinas_Quark]

I'm thinking this shows that when you need the power, it ain't there. Definitely need some form of energy storage - but what? Over the years I have done the figures on warmed concrete heatstore under the house, car batteries charging, pumping water up to a height etc. etc. All are a big set-up problem.
What should we do with the 20kWh we get every day in summer - electrolyse water? (I've had a few small hydrogen/air explosions too)...!!

 

[GreggElectrical]

I can confidently tell you I have never lied when quoting for a system. Its customers that keep telling me they still work when there is no sun. I am always saying " yes, but you will be amazed how much cloud cover affects the output". I find it useful to let the client have a play with my irradience meter and point out that full output isn't achieved until 1000w/m2. Today would be more like 60w/m2.

Don't worry though because your systems will all do well come march! You will be jumping for joy when 4kwp installs regularly return over 100 units per week.

Contrary to popular view that this energy is not needed in summer, if you think about it, you can run your electric shower, cook your tea etc all whist using your free electric.

 

[stevechorner]

I'm thinking this shows that when you need the power, it ain't there. Definitely need some form of energy storage - but what? Over the years I have done the figures on warmed concrete heatstore under the house, car batteries charging, pumping water up to a height etc. etc. All are a big set-up problem.
What should we do with the 20kWh we get every day in summer - electrolyse water? (I've had a few small hydrogen/air explosions too)...!!

I think if I'd got 500W and 400 Watts I'd be wetting myself....225 and 305 for me last 2 days. You get your letter from NPower today Aqui ?

 

[GreggElectrical]

I'm thinking this shows that when you need the power, it ain't there. Definitely need some form of energy storage - but what? Over the years I have done the figures on warmed concrete heatstore under the house, car batteries charging, pumping water up to a height etc. etc. All are a big set-up problem.
What should we do with the 20kWh we get every day in summer - electrolyse water? (I've had a few small hydrogen/air explosions too)...!!

Energy storage.... Now this IS the Future! I have seen two inverter manufactures who have prototype inverters that can link to small lithium ion batteries. The batteries are charged during high generation and the power is then drawn from them when the generation drops. Its not going to keep enough power for all night but will mean you can run washing machines, e.t.c and not worry when a cloud passes over.

 

[langstroth2]

0.671kwh
Really really dull overcast day. Prob about as dark as it gets during the day! Roll on march . We have solar hot water and it's really noticeable the rapid increase in insolation during that month

 

[Aquinas_Quark]

I think if I'd got 500W and 400 Watts I'd be wetting myself....225 and 305 for me last 2 days. You get your letter from NPower today Aqui ?

Nope! I'm thinking I may have to make some unpleasant phone calls yet.....

 

[hionthehill]

345w and 375w for me in southwales SE , 2kw Hyundai His-250MG and SB1700 inverter!! roll on summer!!

 

[hp4020]

16 x Hyundai 250s SMA SB4000TL

Never got light in the North East today, only a measly 0.348 kw generated.

Been installed 3 weeks best to date was 15/10 generated 16.8kw.

 

[stuart99]

I'm in the Midlands, only had solar PV installed at start of Sept 2011. Its a 3.36kW system.

Generation over the past few days is shocking, but has been fairly good for Sept/Oct as a whole though.

4Nov 3.01 kWh
5Nov 2.99 kWh
6Nov 10.87 kWh
7Nov 0.23 kWh
8Nov 0.48 kWh
9Nov 1.58 kWh

My best days..
28 September 2011 16.70
27 September 2011 16.02
29 September 2011 15.94
30 September 2011 15.69
01 October 2011 13.80

Worst
07 November 2011 0.24
08 November 2011 0.48
11 October 2011 0.91
27 October 2011 1.06

 

[Aquinas_Quark]

Hi Alan

I have had two poor days - 700Wh today and 500Wh yesterday. My voltage and power readings have been very similar to yours (no surprises due to the similarities between our systems). I find that unless there is some form of direct sunlight, the panels really don't generate much at all. This very much in contrast to what most of the salesmen claimed when they were quoting!

I'm waiting for some very clear sunny days to see if my generation meets my expectations.

Richard

So what did the installer's check reveal? Alan

 

[Aquinas_Quark]

Hey mate , you heard back from NPower yet.....I am still fearing the worst :>(

Yes finally got acknowledgement of application today 10 Nov. No reference number tho', just says thanks for applying. May take up to 6 weeks for all to be sorted (from WHEN?), that would make it 28th Nov. from application received by nPower. I would say I'm 90% happy....
How you doing with yours? Alan