Found this:
CHARGING: Power in the Paddock for recharging will come from the grid through temporary power boxes we're paying to have installed. We will do our best to accommodate everyone's charging needs but there are a limited number of tie-ins available to us. The power will be RV-style hookups, 50amp 240 volts. If you have access to any sort of travel adapters, you'll want to bring them. Additionally, we will have 3, possible 4 Superchargers installed by TESLA for Model S charging. We ask that all drivers and riders be courteous and share the hookups for recharging during down time. In 2015 we are offering 2 EV auto groups but have not increased our charging capabilities in the paddock. Only vehicles participating in the REFUEL SportElectric Time Trial will have charging "privileges" in the Raceway paddock. All others must agree to charge in the outer lots south of the paddock near the lake. This is the only way we can accommodate more EVs for this event without bringing in generators. If there is enough charging capability in the paddock for non-TT participants, we ask that you request permission to charge in the paddock before doing so. The TT (and thus paddock charging for cars) is limited to 35 vehicles. Please be aware that we may limit participation in the TT to experienced drivers. If you want to sign up for the TT but are not able to, we may be able to accommodate additional drivers who are willing to charge in the outer lot.
http://speedventures.com/events/eventdetail.aspx?id=525