Both Solar on one roof - Meter it!

November '10: We welcome the arrival of these PV panels in a house in Willow Rd, WB, installed by MG Renewables. It is the ideal location, pure south facing and a clear modern roof, space for 16x235Watt panels with only the centre portion left for the existing vacuum tube solar water panels, and space for more in the future.
Kas, the owner has set up a spreadsheet to record the daily input, this is one way to 'enjoy' the panels - monitoring their progress and comparing it with weather information. He has had solar water heating panels for a couple of years, but without any form of metering, so there's no way to know if it's doing any good. With a regular metering regime and his new PV panels he can meter the PV, the day and night electricity, and the gas too, comparing tariffs and calculating income.It becomes a bit of a hobby, and one can look forward on sunny days to see what the score will be, a bit like anticipating a 5 day cricket match result.
See the growing sheet at: tinyurl.com/Kas-meter

Metering is a way to save energy

It is amazing how the simple act of storing your meter readings can save energy. Somehow, the competitive instinct kicks in, and you try harder to get a lower meter reading than the week or day before - result is that you save energy! It isn't just about the design of the house or its boiler or insulation - energy saving is also linked to lifestyle.

It is worth doing the metering record for Electric, Gas, and even Water if that is on a meter. If you have a PV roof, it is essential so you can calculate your payback! You can compare it with the amount you have to import.

There is a more detailed article about this on the WB Ecohouses blogsite. See the Metering Page on there. It also contains tips on how to convert your Gas to kWh.

If you want an XLS file with the simple algorithm for calculating dates and times and day number, write to rushcliffesolar@gmail.com - otherwise just build your own one a day to day or week to week basis, and you will see how the house and how you perform.

Does your meter go in reverse?

19 April : Some people ask if the meter will literally 'go in reverse' if you have a good day of photovoltaic generation.  Mine doesn't, it remains static during the day and only moves forward if we do some ironing or use the kettle a lot, or the heating has to be on. After sunset, it rolls along as a normal one would. Chris Brook of EvoEnergy has provided me with an answer:

"Whether your meter works in reverse depends on the type of meter installed. Old style mechanical meters will run in reverse and people with these will get an extra, though unintended, financial benefit. If you have a more modern electronic meter this will accurately record the units of electricity you import from the grid. It will be stationary if the amount of energy you are producing exceeds your current demand. Your [OfGem] generation meter will tell you accurately how much you have produced. In terms of what you export, this will only be measured accurately if your electricity supplier installs an import/export meter. The only energy provider currently doing this is Scottish and Southern Electricity. Other major providers intend to estimate how much you have exported based on the amount generated. As far as we know most are going with a generous 50/50 estimate.

Energy you produce will flow to its nearest point of use. If there is demand within your home this will be nearest. If you produce more than you currently demand the excess will flow to its nearest point of use via your mains electricity cable. In all likelihood there will be demand from one of your neighbours and this is where the electricity will be used. The electricity flows via the grid to your neighbours."

In this way, there is no transmission loss. There are no substations or transformers to go through, which eat energy at the change over. It is another reason why the generous Feed in Tariff can be justified. For every kilowatt used by your or your neighbours, it is saving the heat equivalent of 3 kilowatts of coal in a distant power station.