Annual outout will vary from place to place and from year to year. We present yield in two ways. Firstly, through the mandatory SAP (standard assessment procedure). This assumes that for every kWp of PV installed, 850kWh will be generated. In southern parts of England we know we yield more than this so we perform geographically accurate yield predictions for each project. It is not uncommon to find systems in the south west of England yielding over 1000kWh per kWp installed. We will produce a yield prediction in your quote documentation.