My 4.8kwh (+1kwh after a few months) system, with 14 KW of battery storage, has now been up and running for 12 months. It supplies 2 households (me and bro) and a farm business. System is grid tied to import when no solar, but is set to zero export. Figures for the 12 month period are as follows
5876 KW total consumption
4512 KW solar generation
1915 KW imported from Grid
My business tariff over this period has been 60p a kw. So figures are;
cost of imported electric £1149 (was actually less as there were some government subsidies up until April 2023)
due to inverter inefficiencies the actual energy saved via the Solar amounts to 5876-1915= 3961KW, or a saving of £2376 over the year.
System cost was around £12K as a DIY install using Victron equipment. Next 3 years I have fixed tariff at 29p/kwh so I expect savings to halve. Would suggest a 9-10 year pay back on the system on current usage.