You could try to integrate into another VPP. If there is none (or no suitable) you have to either wait until someone starts one, or take the initiative ;) //Ed

You could try to integrate into another VPP. If there is none (or no suitable) you have to either wait until someone starts one, or take the initiative ;) //Edit: I suppose only allowing Tesla is for two reasons: 1. They can do the necessary software adjustments very easily (homogenous system) and 2. this adds an incentive for consumers to buy Tesla over other solutions.