I think EVU blocking is typically a feature that enables you to block the power supply from the energy provider in situations where there is an excess production of renewable energy in your system. When your solar panels or other renewable energy sources generate more energy than your household or building requires, the excess energy is often fed back into the grid. However, in some cases, it may be more beneficial to keep the energy within your own system, rather than exporting it back to the grid.

So it’s a way to prevent the energy from being exported back to the grid and instead using it to power other appliances in your home or building. This feature can help you maximise the use of your renewable energy and reduce your dependence on the grid.

EVU blocking should only be used in specific situations and should be configured correctly to prevent any issues with your energy supply.

I'm not sure if that helps you.