It doesn't get cheaper than this: Charge using your own solar power  

As a PV system owner, you'll already be aware of the environmental and economic advantages of generating your own energy. As the owner of an electric car, you can significantly increase your potential savings with the Fronius Wattpilot. This electric car charger can switch between 1 and 3-phase automatically and regulate its output in 1 ampere steps. This allows it to make optimal use of the surplus PV energy from 1.38 kW to 22 kW and use any surplus energy from your PV system to sustainably charge your vehicle at virtually no cost. 

Your benefits: you save while you charge and make optimum use of your PV system so that it pays for itself faster. 

Optimal power distribution – with Dynamic Load Balancing

Whether with excess energy from your photovoltaic system or with power from the grid, Dynamic Load Balancing allows you to use the entire available amount of your household electricity optimally. With one or more installed charging stations, not only can you charge your electric cars at the same time, but also in an energy-optimised manner. The energy required can be controlled and distributed dynamically among up to three vehicles being charged. The advantage for you is that both the performance of your photovoltaic system as well as the energy consumed in the household are taken into account. This saves high connection costs and also effectively prevents overloading at the house connection. And best of all, thanks to Dynamic Load Balancing, you can prioritise precisely and therefore achieve even higher charging power.