Generate Hot water using Solar Thermal - heats water all year round - in winter acts like a pre-heater of water for gas to top up and in summer takes over the water heating.
I like the fact it heats water at bottom of tank which is always colder than the top and a big temperature difference. Saves a lot of CO2. Had this done 5 years ago and no problems.
Generate Electricity using Solar PV panels - great investment as the money I get on the FIT payment will pay back the investment very quickly and also saves a lot of electricity and CO2. Best investment I made on the ROI front. Had some tripping of circuit breakers at first but supplier great (The Green Shop in Bisley Glos) and quickly sorted it out - working great now for nearly 2 years and very happy with them. We put the washing maching on now when the sun shines !
Install Solar PVs with any spare cash - great investment and index linked and future proofef - wish I had done it sooner.
Shower in the day if you can to get the best from your solar water heating and check out the weather forecast if its sunny you can put on your dishwasher etc to use the free electricity. Although if you can't do this then use a timer to switch on the appliances.