FREDDY works with all electricity metres. You no longer have to draw the electricity you generated yourself from the grid. This slows down the electricity consumption and the electricity metre slows down or even stops. When FREDDY produces a surplus, the electricity flows back into the grid. Old electricity metres then turn backwards. Modern electricity metres have a backstop and stop. If you have more than 12 FREDDYs, please contact an electrician. We recommend FREDDY in combination with a smart metre. Electricity Metre