Renewables: "talking 'bout my generation"

sly_dog_jonah

Cavemanu wrote: »

I've been comparing my energy consumption bills for several years, as we are quite low users of energy and live in a modern house. We have noticed around 42% electricity consumption reduction and interestingly around 21% consumption in gas since the PV has been installed. Some of this reduction from the previous year is probably due to temperatures/weather etc.
Have any forum-ites got any energy consumption reductions they could share? I'm getting too impatient to wait an entire year and thought some people who have had their systems awhile might have some longer term bill savings they might be able to mention.
I think our energy consumption patterns/habits have remained pretty much the same, except that I do try use appliances in daytime when sun is out.
thanks in advance for your input!

Hi Cavemanu,

I haven't crunched the numbers recently to work out the average Electricity savings since our panels were installed late October 2011, but here's a graphical view of our PV generation, Electricity usage and Gas usage. The white bars are previous year's values for comparison (if available), green/red bars illustrate above/below average generation and below/above average usage. Since we moved into our new build house late Dec 2010 there's no year-on-year comparisons available for August-November yet:
Solar PV Generation
Electricity Usage
Gas Usage

All the graphs are in kWh rather than £'s since price rises over the past 2 years will skew the figures otherwise.

April electricity usage this year was particularly low because we were away for 10days. The colder spring is also evident in the gas comparison (central heating was kept on until later in spring). The July value for this year is extrapolated from 1day's reading, so can be ignored. We cook with electric but central heating & water is gas-powered. We also have an electric fire in the lounge which got a bit of excess usage in winter 2010/11 before we fully appreciated the cost! I work from home so can optimise our use of appliances to when the sun is shining.

The electricity import savings peaked at 45% in April but were only 25% in June due to the poor weather, and May's saving was 33%.

Despite an awful morning of torrential rain yesterday the afternoon brightened up and we logged a 14.8kWh to kick off July, which is pretty good considering our orientation (which favours morning production). The rain's back again this morning though.

Martyn1981

SDJ - thanks, very interesting. Visually, it looks like you're cutting leccy by about a 1/3. We seem to be doing similar, hoping to knock approx 1,000 units off the old 2,700pa consumption.

Bad news re gas, changed to EDF first week of July 2011, they mucked up the gas transfer and haven't been charging me anything. I chased for 4 months with e-mails and phonecalls, then realised that they probably couldn't back date their bills more than 12 months.

I was hoping that the first days (of July last year) would start to 'fall off' the bottom next week, but they've just made the gas account live. So close, but no cigar!

Mart.

SiEd

Why is there a difference in the SAP prediction and the PVGIS prediction? There seems to be a difference of approx 180 kwh for my installation

Martyn1981

SiEd wrote: »

Why is there a difference in the SAP prediction and the PVGIS prediction? There seems to be a difference of approx 180 kwh for my installation

Hiya, SAP is 'standard assessment procedure' and takes no account of your location, nor local climate which can be effected by mountains, forests etc.

Edit: Sorry, should have explained that the government only wants companies to quote against a single specific average, that way it prevents salesmen from 'accidentally' over quoting generation. This way if you had a number of salesmen estimate your generation against SAP, the results should be fairly consistent.

I think the SAP figures are based on the Sheffield University research levels, so as an extremely rough (and fairly inaccurate) guide, below Sheffield should be more than SAP and vice versa.

(Sorry, trying to add a link, but all the good examples seem to be on PV company sales pages.)

Hence why PVGIS classic is more accurate as it reflects local solar levels, and PVGIS climate seems even better again as it considers actual results, which can be affected by climate.

Mart.

Cavemanu

Thanks SDJ that's really helpful, much appreciated! :-)

shafeeq

Hi

3.06 kw for me today

EricMears

5.789 kWh today
16.701 yesterday

pvgis would suggest I should expect to average 14.7 kWh/day in July. Not holding my breath for a record month

Oscargrouch

EricMears wrote: »

pvgis would suggest I should expect to average 14.7 kWh/day in July. Not holding my breath for a record month

4.1kWh for me, only 47% of my daily PVGIS average; I'm with you Eric. :rotfl:

At least I was not wrong in yesterdays statement; yesterday is still the best this month....:D

jackieblack

8kWh for me yesterday and 10kWh on Sunday
(So yes, Oscargrouch, 1st July still the best day of the month so far!:D)
My target for July is a smidgeon over 8kWh per day so right on track so far, however the month is still young.......:(

WestonDave

4Kwh yesterday (off 4kWp!) - I had to press the button twice to check it. Grr where is summer? (Hopefully its saving all its nice sunny weather for when I go camping later in the month - yeah right!). Wonder if I can fit little water wheels in my guttering down pipes - they might have generated more last month! Still 4 covers the interest so can't be too unhappy - today is more of the same but we wait and hope!