PV Generation and Electricity Meters: 6 Month Update

FREE BRIEFING: due to overwhelming interest in the issue of ‘electricity usage meters going backwards after PV installation’ we have produced a briefing note on the topic. Click here to contact us to request your FREE copy

So, I’m now over 6 months into my ownership of PV panels and the vagaries of the seasons, and their effect on electricity production, are becoming clear in relation to the issues with renewable generation.

The first 3 months of production, roughly July through to September, produced approximately 311 KWh of electricity (and an income of about £140), the second 3 months, October through December, produced a rather less impressive 129 KWh (and an income of about £57).  So for 6 months the total generation and income for my 1.67KW peak system is 440 KWH and about £200.  If this is projected for a full 12 months it will mean a total production of approx 1000 KWh and a yearly yield of around £400-500.  So payback on an £8K system, based on those generation rates will be nearly 20 years, and that is with the 43.3pence tariff.  I haven’t included my reduction on my electricity bill here as I had the issue of my backward running meter in place for the first 2 months of PV production (the highest 2 months of production so far) so it’s hard to tell the true reduction in my use of grid electricity through those months. However, my typical annual usage is low anyway (about 1700 KWh historically, compared with a stated national average of 3300 KWh per UK household) so I cannot expect a huge reduction in my yearly bills, £100 max I predict.

Talking about electricity use meters going backwards, the number of searches that have brought people to my website using a variation on this theme is now in the hundreds, and the blog post has been read 230 times, and I regularly get 5-6 hits a day on the topic.  So this is a widespread problem.  With 50,000 plus installations in already, and no-one systematically tackling the issue, energy suppliers are going to have a merry old time trying to sort out very unusually low electricity bills in the summer months, and I wonder how vigorously they will try to claw back that missing historical electricity usage that has been lost to the backward running meters?

Looking at other seasonal factors, the snow we have had recently have very much affected generation, on the days of snow fall we have produced exactly zero KW of electricity, it’s the first time absolutely no generation has occurred, as even on the cloudiest, most overcast day we have still generated something.  I had hoped that the panels’ surfaces were sufficiently slippery and on enough of an angle that would mean the snow would not settle too much and hence would self clean, but that obviously hasn’t been the case.  So you can imagine that in a heavy and persistent snowfall all PV generation could come to a standstill.  An issue I wonder if the powers that be have taken into account in their forward projections.

So, I await with interest the next 6 months.  We are now into a six month period with increasing daylight hours.  I have even noticed a difference from January to February in terms of how early generation starts in the mornings.  Given that our summer from July onwards was a bit of a wash out, I’m hopeful that the second 6 months will be more productive than the first., but only time will tell. Watch this space.

Related blog posts:

Being a PV generator: Lessons I have learnt Part 1

Being a PV generator: Lesson learnt Part 2

PV systems and meters running backwards: need for clear guidance


3 comments… add one
  • Richard February 21, 2012, 8:52 am

    Frightening payback calc! Especially as that's undiscounted and doesn't factor in the possibility of a replacement inverter at some point. Hopefully May/June/July with the sun at its highest will prove more productive. What pitch and orientation are your panels?
    Mine have produced 67 kWh since 2nd Feb which, considering it's a bigger system (2.88 kWp) is about on a par with your second period production. I had fun the other day watching the meter oscillate from >2 kW to <0.1 and back to >2 as the sun disappeared behind a cloud and reappeared again. Now that's what I call intermittency!
    Did you have to wait ages for your supplier to sort out admin details etc? My lot acknowledged my application and said it would take 6 weeks to "do all the checks"!!!

    • Paula February 21, 2012, 11:23 am

      Hi Richard
      Yep it isn’t great. But bear in mind that July onwards was a pretty bad summer, and it was Mar, Apr and May that was recording record generation levels in PV systems. I’ve seen a big jump in my generation levels even in the last few weeks and am generating much earlier than just a few weeks ago even, and getting up to 300-350 watts earlish in morning this compares to not getting above 100 watts in Jan. My orientation isn’t perfect either, its South West. Not sure of pitch, would have to go back to the paperwork for that. I’m confident that the second half of my first year will generate much more than my first. I’ll do a download of Feb’s generation at end of month and let you know what that is

      Ecotricity were pretty efficient with my paperwork, I’m pretty sure it didnt take 6 weeks. But there again, there is probably a rush on paperwork at the moment!

      BTW – I’m getting record numbers of visitors to my site with the search term of ‘my meter is going backwards after pv install’ – its incredibel and i guess is coinciding with the rush to install in Dec/Jan. I intend to write a short briefing on it as there is obviously a lot of confusion out there!

  • Richard February 24, 2012, 10:27 am

    I've had people knocking on the door asking about the system! We are fairly prominent – facing a corner of the Common. I'm thinking of charging a finder's fee!


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