In a spare hour of time, I played around with the records I now hold of my house's consumption of power over the last year and a half. The plan was to use it as a basis for comparing the cost of buying electricity from different suppliers. It was spreadsheet heaven and the results were surprising. Previous spreadsheets had shown me that the second most important factor in making the PV array pay was by paying as little as possible for for the electricity I would have to buy.
I waded through the morass of tables and systems for charging for electricity and standardised on a typical three-month period to which I could apply each company's tariff. This is becaue many tariff rules apply to the quarter of a year.
It is saddening to see how complex the market is and how opaque it must be for the vast majority of consumers. There are two main charging systems; some have a daily standing charge, others don't but they have you pay a higher unit cost for an initial quantity of power which drops to a low tariff once you have used a set number of units within a certain time. In negotiating this mess, the spreadsheet is invaluable.
My current supplier, Scottish Power, is run-of-the-mill. It matched a slew of companies by being around £300 for the sample quarter. Suppliers of so-called green energy were the most expensive, going well above the £300 mark. This is to be expected as you're paying a premium for buying energy from wholly renewable sources.
The shocker was EDF energy. At £208 for the quarter, it was well below its nearest rival and nearly two-thirds of what I pay now. The catch is that this is a promotional rate which will only last until summer 2011, but even their standard rate is competitive. I believe that part of the reason for the low price is an aggressive push into Scottish Power's home market. Like most of the other large suppliers, there were further discounts for direct debit payment.
If I weren't about to install a solar PV system, I'd likely jump on this wagon, or at least investigate further. However, once the generating system is built, I'll be placing EDF at the top of the list of suppliers to investigate though I wonder what their reaction will be to me wanting to sell them power through the FiTs scheme. [Note from 10 May: I did change to EDF, with 7 May being my official changeover date.]