The Great 'Get Paid To Generate Energy' Hunt

free_juice?

furndire wrote: »

An incredible 15 units for us today. Febuary has started off well for us.

Thanks, I've been looking out for real world figures like that to compare with my own system. Could I ask that you let us know the size of your system in future? :T

My 3.3kW system produced only 12.25 kWh on the 8th (sunny all day) which didn't compare too well with other figures posted in various threads. Of course the figures only begin to be comparable when the sun shines all day.

In January I scored 95% of my predicted output and so far this month it is 90%. Given how dark it has been today and many other days recently I'm surprised it is that close to 100%.

furndire

Ours is a 3.96 system but we are in Sc**thorpe - starting to think we are sunny Scunny.


Have you thought about letting Nang have your monthly figures and charting them on http://www.uksolarcasestudy.co.uk/ systems in detail

The more the merrier

free_juice?

furndire wrote: »

Ours is a 3.96 system but we are in Sc**thorpe - starting to think we are sunny Scunny.

Proportionately only a tiny bit more than mine then.

In the 35 days since installation I have seen the sun only on seven days and only once for more than a few hours.

free_juice?

furndire wrote: »

Ours is a 3.96 system but we are in Sc**thorpe - starting to think we are sunny Scunny.


Have you thought about letting Nang have your monthly figures and charting them on http://www.uksolarcasestudy.co.uk/ systems in detail

The more the merrier

My system automatically logs output at 15 minute intervals and I have been posting a daily summary to the web. My Excel skills are not great but I have all the raw data if anybody should want it.

www.malcolmknight.co.uk/solar

noncom_2

Sorry, I've tried to search the forums for a simple answer to this, but haven't found anything convincing.

My system's been up and running for about three and a half months now. I'm logging the amount generated on a monthly basis (I'm too busy and not obsessive enough to do it daily!). Obviously it's winter so we're not getting fantastic amounts out of it yet, but it would be useful to be able to guage whether we're "on track" for the predicted annual output.

Is there a simple way to see either: the predicted monthly output as a percentage of the annual output for a UK system, or a monthly output prediction for a 3.9kW system in the Midlands? I realise the latter depends on orientation, elevation angle etc as well, so in a way the simpler calculation might be more useful for me. (Our system is split into two separate strings feeding their own inverters, at the same azimuth but different elevation angles making the online predictors hard to use)

Thanks
Andy

Equaliser123

noncom wrote: »

Sorry, I've tried to search the forums for a simple answer to this, but haven't found anything convincing.

My system's been up and running for about three and a half months now. I'm logging the amount generated on a monthly basis (I'm too busy and not obsessive enough to do it daily!). Obviously it's winter so we're not getting fantastic amounts out of it yet, but it would be useful to be able to guage whether we're "on track" for the predicted annual output.

Is there a simple way to see either: the predicted monthly output as a percentage of the annual output for a UK system, or a monthly output prediction for a 3.9kW system in the Midlands? I realise the latter depends on orientation, elevation angle etc as well, so in a way the simpler calculation might be more useful for me. (Our system is split into two separate strings feeding their own inverters, at the same azimuth but different elevation angles making the online predictors hard to use)

Thanks
Andy

The EU produces a very comprehensive prediction tool on its website. Sorry I don't have the complete link to hand.

noncom_2

This one http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php maybe?

I've tried that, but I can't see any logic for choosing a value for the "system losses" box.

Putting in the rated kWp value of my system and the default losses value, along with the AVERAGE incline of the two strings and their azimuth, I get a prediction of about 3000kWh per year, which is about 15% lower than the "standard" prediction used in quotes for the system when I was considering installation.

Given that many people state that they are exceeding the standard prediction, and that the company which installed the system also used their own predictor which gave slightly higher figures than the standard one, I wonder why this calculator seems to be pessimistic.

Andy

zeupater

noncom wrote: »

This one http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php maybe?

I've tried that, but I can't see any logic for choosing a value for the "system losses" box.

Putting in the rated kWp value of my system and the default losses value, along with the AVERAGE incline of the two strings and their azimuth, I get a prediction of about 3000kWh per year, which is about 15% lower than the "standard" prediction used in quotes for the system when I was considering installation.

Given that many people state that they are exceeding the standard prediction, and that the company which installed the system also used their own predictor which gave slightly higher figures than the standard one, I wonder why this calculator seems to be pessimistic.

Andy

Hi

Try the v4 database (APPS4) instead, it uses an updated dataset (CMSAF - which needs to be selected) delivering improved accuracy, increasing the expected insolation in most (non-hilly/mountainous) areas .... http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php ... the degree of change between the two datasets is described in the following link and represented in the included net change maps ... http://re.jrc.ec.europa.eu/pvgis/PVGIS_new_features.html


Remember, the insolation data is based on averaged measurements ... recent weather conditions have produced better than average insolation .... See ..... http://www.metoffice.gov.uk/climate/uk/anomacts/ ... and look at the Sunshine anomaly maps for recent months/years ....

HTH
Z

Dave_Fowler

noncom wrote: »

This one http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php maybe?

I've tried that, but I can't see any logic for choosing a value for the "system losses" box.

Putting in the rated kWp value of my system and the default losses value, along with the AVERAGE incline of the two strings and their azimuth, I get a prediction of about 3000kWh per year, which is about 15% lower than the "standard" prediction used in quotes for the system when I was considering installation.

Given that many people state that they are exceeding the standard prediction, and that the company which installed the system also used their own predictor which gave slightly higher figures than the standard one, I wonder why this calculator seems to be pessimistic.


Andy

On the top section of page on the link you give, there is a further link to a newer prediction page which makes allowances for altitude and also introduces a newer set of data - PVGIS-CMSAF. These changes produce a much more optimistic prediction.

I think the system losses they set as default (14%) may be a little pessimistic. Most inverters run at 5% loss if you keep the output above 50% of their claimed maximum and cable losses shouldn't be more than 1 or 2% if the cable-runs aren't excessively long.

I appear to have cross-posted with Zeupater on the newer data set. That will teach me to take so long to complete the reply.

Dave F

grahamc2003

noncom wrote: »

Putting in the rated kWp value of my system and the default losses value, along with the AVERAGE incline of the two strings and their azimuth, I get a prediction of about 3000kWh per year, which is about 15% lower than the "standard" prediction used in quotes for the system when I was considering installation.


Andy

What's the average deviation from S of your panels? My roof would need two sets of panels, each at 45 deg from S (one pointing SE, the other SW). If you resolve the angle to give you the area pointing south, you need sin45, which is .85 i.e. my roof would only get 85% of the solar energy of a S facing roof of the same area. Perhaps that's where your 15% loss comes from too?

I notice you say you have 2 inverters, one for each string. I had that in my quote too, but a discussion on here implied only one inverter was necessary for two strings. Anyone throw any light on that?