LED lightbulbs
Here is a beginner's guide to buying LED lightbulbs.
Old-style halogen and other bulbs are no longer sold; LED bulbs - using a fraction of the electricity, and now a similar price to the old ones - are now the norm.
And forget that cold blue colour: LED now comes in a range of light-colours, including lovely warm ones.
LED will immediately start saving you a lot of money and will carry on saving you a lot of money every year.
You've probably been spending £10-15/ year in electricity running a single old-style (halogen) bulb for a few hours a day, and the bulb needed replacing every couple of years.
An LED equivalent costs only £1/year to run, and the bulb can last for 20 years.
Lithium storage batteries
A few years ago I installed lithium storage batteries so that I can use even more of the electricity generated by my solar PV panels; see this info sheet for details (note that the price of storage batteries has gone down since this was written).
Here I am with my storage batteries and solar inverter