# The MCS self-consumption calculations in the Performance task don't work for my project - why?

The MCS calculations won’t work for projects with an annual generation greater than 6000 kWh, annual consumption not between 1500-6000kWh or with battery storage over 15.1kWh.

For these situations, we recommend using the Easy PV [Consumption task](https://help.easy-pv.co.uk/books/performance-and-consumption/page/getting-started-with-the-consumption-task "Consumption task") to generate accurate system projections and then ensure you select the Easy PV calculations in the [Financial task](https://help.easy-pv.co.uk/books/financial-task/page/using-the-financial-task "Using the financial task").