[ChoGGi]

The panels on my roof go straight to the energy company anyways. You need to add batteries to use it yourself.

[IshKebab]

Only the surplus goes straight to the energy company. If you're consuming any energy and producing it from solar you'll use your own solar first, even without batteries.

[elric]

Which is maybe 10-20% for most people without batteries. Better than nothing, but not great.