A normal a 4 KW system is made up of 16 of 250-watt panels.
A 4 kW solar panel system with a top-rated panel and ENPHASE microinverters should cost around the £7000 mark. There are many decent, good quality installation companies in your area which will quote you around that price.
This is an example of a typically installed system in the United Kingdom, but prices vary with many of solar companies overcharging, so always get three quotes.
You can start by using our own ‘get a quote’ service at: