Windmill: 10% bill reduction. 20% if upgraded. 5 windmills will contribute to bill reduction, at max, meaning 5 un-upgraded windmills will drop your bills by 50% and 5 upgraded will mean no bills!
Twizy: The car now gives a 10% bill reduction. OPTIONALLY: It will also now go super mega fast and save a hell of a lot of time getting places, at the expense of only one sim being able to ride at a time. Do not follow your sim while driving because you'll get slowdown as the game rushes from one area to the next, instead watch from map view.
Solar Panels: 5% bill reduction, 10% if upgraded. Limit is 10, meaning 10 solar panels is a 50% reduction and 10 upgraded panels is a 10)% reduction.
I don't know for sure, but I think having over 100% bill reduction means you actually earn money. So that's cool!
Both files are in one rar, only use ONE!