Recently the British govt decided to force energy companies to pay people who installed photovoltaic solar panels on their roof. The rates are as follows:
Main Tariff: 41.3 p/kWh for everything you generate plus
Export Tariff: 3 p/kWh for what they deem you export, e.g. they might say you use 50% and you export 50% of what the panels generate.
Both tariffs rise by inflation rate r = 2.4% each year.
A typical 1kW system in the UK generates 850 kWh per year. A 2.0 kW system will generate twice this and so on, whatever the size. Anything under 4 kW qualifies.
Okay, so far, so good. I want to work out three short formulas that will predict my earnings from
Main tariff (m)
Export Tariff (e)
for any given year 1-25
rate rise = 2.4% (r)
For example, year n=1,2,3,4....25 (the last year they'll pay).
I can do this on a long complex spreadsheet, but I'm sure that there is a shorter formulaic way to do this.
It's a good problem to solve actually, so I hope someone can provide the formulas.