rKarmaConspiracy at the highest level of government ! <| sep |> While this is inflation adjusted , I ' m not sure CPI would make the best relative cost adjustment . Wage based inflation calculator would be more accurate due to the high amount of human capitol in education . Looking into this I found some national averagessalariesroseinthe 80 s a ndtheyvebeenslippingsince , but there is still some controversy in the data of relative increases in wage . <| sep |> Even then , if you ' re in the US , the public utilities have struck arrangements nearly everywhere in the US that sees them crediting not paying for extra generation , capping the maximum amount credited , capping the maximum amount fed into the grid , and so on . Basically , the lobbyists got there and drafted legislation screwing the consumer . If you wanted to know what amount of surplus would be needed , you need to know your time of day usage . Most houses use the bulk of their electricity after sunset . So you would need to generate enough during daytime to power the house and store whatever would be needed for the night time . Then you have to factor in generation losses due to weather , and losses due to shorter days , etc . It ' s not something we could answer for you .