Systems Larger than 4kW

The information on this page is now out of date - from 15 January 2016 some of the rules have changed

It is possible to install a system larger than 4kW on a domestic house. However, if you exceed the 4kW mark you get paid a slightly lower rate for every unit generated. In practice, it is probably only worth going over 4kW if 6kW or more can be installed on your roof. This would require a roof of approximately 4m x 12m.

However, the 4kW mark is slightly daft anyway - and has caused confusion throughout the industry. When connecting a Small Scale Electricity Generator (ie - solar panels or a wind turbine) to the national grid, the installation is required to met legislation set our by the District Network Operator. Through out the UK, most domestic installations under 4kW are installed under G83 rules - G83 rules state that a system must not exceed 16A per phase. On most houses this will be 3.68kW (230V x 16A) - which is less than 4kW! To get around this, inverters limit the AC output of the system to 16A - in practice a 4kW system would rarely exceed 16A per phase as conditions are rarely ideal! Current limiting is most likely to happen on a cool sunny spring day - click HERE to find out why.  If you wanted to exceed 16A, the inverter needs to comply with G59 rules. If you have a three phase supply, it is possible to install just over 11kW - so probably best to make use of the 10kW FiT.

If this is giving you a headache there is no need to worry - we deal with this on a regular basis and handle everything for you.