A 3kW system (typically 10 panels) will generate around 3100kWh in a year in Surrey. You get a government incentive (called feed-in-tariff FiT) for anything you generate. What you generate avoids you buying it from your energy supplier via the grid. And excess electricity is feed back (exported) into the grid for which you earn money from your electricity supplier. PV panels generate in light cloud conditions as well as sun. Obviously their is no generation in late evening and night after sun down. The payback period is around 7 to 9 years. Panels last 20+ years. Typically the return on investment is around 6% (much better than the savings bank).
Often solar PV generation is during the day time when people are away from the property and so electricity consumption is low, so lots of excess solar generated electricity is exported to the grid. With a battery storage system this excess electricity is used to charge batteries. The batteries then power the house in the evening and overnight. From around March to November the property can be almost self powering using self generated solar electricity. Over the winter period you will need to augment some of the electricity needs with grid electricity. But even then you can use the battery system to charge the batteries overnight using cheap economy-7 electriticity.
Electric vehicles (EV) are coming of age. They create zero local emissions. They only cost around 2p/mile to charge, compared with around 11p/mile for petrol of diesel fuel. Because EV's have no gearbox, differential gears, clutch, internal combustion engine they have very few moving parts and inherently have low maintenance costs and low failure rates. Their component costs are governed by 'Moore's law' the same principle that has seen consumer electronics prices drop and drop; whereas everything else in life goes up and up.
With an EV charging point you can charge your EV overnight using cheap tariff economy-7 electricity (say 6 to 7p/kWh). Using a 3.2kW charging point you can recharge a typical EV in around 10hours. Using a 7.2kW charging point you can recharge a typical EV in around 5hours (this is similar to a power shower electricity capacity).
Remember: you can use a 13 Amp socket to recharge an EV (with the right cable)- but these were never designed for this purpose and the electrical protection is not really adequate; and it takes a long time to charge.
Now you can use all that excess solar generated electricity to charge the EV (if it is present during the day). Potentially you can be saving say £1000 per annum in fuel costs. And being good to the environment. Especially by avoiding the local pollution effects such as particulates (PM2.5, PM10), nitrogen dioxide and other nasties. The integration of solar and EV is a real game changer.
This is the panacea.
Soon EV manufacturers will be releasing vehicles and technology that allows the vehicle's battery to power the house (ie. reserve flow of electricity), making even better use of energy to avoid taking expensive electricity from the grid via the energy supplier. Customers can then sign up to provide national grid support contracts, and earn extra money, so that the EV energy can be used to support grid peaks (with very clear limitation on how much of the EV energy can be used, so it is still ready to use first thing in the morning).
All of this, will be what one can call 'disruptive technology' and is likely to transform both the energy industry and the vehicle transportation industry in the next 10 years.