This is worked out from weekly or fortnightly meter readings which are then divided by 7 or 14 to give average daily figures. Not the most accurate figures ever, but the best we have.
The gas figures began in Jan 2012 (the door to the boiler-room where the gas meter is, was jammed shut through the winter!) and the solar PV figures began at the end of November 2011 when the panels and inverter were installed.
You can see how from March onwards, the obvious synchronised changes of the incoming electricity usage and solar PV generation figures made me realise that there was a problem: any power we generate but don't use is exported to the national grid as with most domestic systems (we get the feed-in-tarrif export payment on 50% of our generation for that).
Basically, whenever we had a stunning week for generation (end March, early June, early July) the electricity import figures have increased even further to outstrip the generation.
Where the problem arose is that our electricity import meter (Siemens S2AS) is not properly programmed to account for micro-generation. It includes an "anti-fraud" bug which means that it is setup to log electricity units IN and OUT of the property and counts them all as imported units which must be charged for. This means that we are being charged for what we export, which should not be the case.
The reason I believe the electricity in & generation out figures have coincided for the recent week in early Aug (18 units per day, 124 units for the week) is that recently we've been running the dishwasher during the day almost exclusively, whereas we usually only get round to it at night. This means that our import and export figures have been lower as we've bought in less power and used more of what we've generated.
As you can see from the first week in Sept, the lurching increase in apparent electricity import is clearly linked to the fact that we've had a great week for generation.
The 2nd week in Sept has not been as good as the first but if you look at the first Mon - Sun week in Sept, it was our best week ever with 142.6 units - even beating the previous best at the end of March - 140 kWh in 7 days. So much for the Summer between June & August - wettest for 100 years apparently!
daily electricity and gas use / solarPV generation units
No comments:
Post a Comment