Home solar, my findings after 12 months

lazyade

When I looked at getting home pv solar panels back in September 2013 I really struggled to find data on typical annual yield for a 4KW home system. So now I've had my installation for 12 months I wanted to post my findings to help other people considering a solar installation.

Here's an overview of the installation:

- install date 6 November 2013
- size 3.92 KW
- panels - Sunpower 327w (x12)
- inverter SMA 3300
- location - East Kent
- facing east
- yield as of 2 November 3,665 KW
- tax free income from Feed In- Tariff £630 (both generation with
deemed export)
- average daily yield 11.35 KW, peak 17.62 KW (May to June) and lowest 2.72 KW (November to mid-January)
- installer Solar Advanced Systems in Edenbridge, Kent

As some of you may know the government publishes a fixed formula for calculating annual yield based on postcode, installation direction and roof pitch (the SAP 2009 standard), my installer estimated 2,883 KW so I'm +782KW or 27% more - which has been a nice surprise (especially as the installed roof faces east). Obviously it's been quite a decent summer but that is offset by a really rainy January.

I chose the Sunpower panels as they are one of the most efficient panels on the market (20% efficiency) - I figured that over the long term the extra cost would be recouped through greater yield.

I also purchased a solar switch. This device connects to your water heating immersion, when your are net generating (ie. generating more than you're using), rather than sending the surplus to the grid, it sends the power to the immersion to heat the hot water. This has meant that May to September I used no energy to heat my hot water - another save.

Obviously weather sways these figures a lot but my electric consumption is down 22% over the year and my gas consumption is down 25% (a good part likely down to not having to heat hot water in the summer months). These savings are of course on top of the money you get from the Feed-In Tariff payments.

Hope this has been helpful.

tunnel

It may help if you added your install cost, regulars on here know that the sunpowers come at a premium price whereas newbies to solar may look at your figures and think wow...i'll have some of that without realising the "extra" cost involved for your particular set up.


Nice to see you're doing so well though, very good figures for an easterly aspect system

lazyade

Installation cost was around £7,900. Didn't put on original post so as not to detract from the purpose of the post - which was to share the yield info.

ed110220

Hi,

that's some good info. How does your yield compare with the PVGIS (http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php) estimate? If I choose an East Kent town at random, Ashford, and put in 4 kW, 35 degree slope and -90 azimuth it estimates 3280 kWh/year.

Ed