Using Tesla’s listed specs, the Model S miles/kWh ranges from 3.12 mi/kWh (for the 80kWh battery) to 3.47 (for the 60 kWh) battery. Let’s say it gets 3 mi/kWh both to account for less-than-optimal driving and to simplify calculations. So you’ll need 8.3 kWh a day to drive 25 miles. Let’s round it to 10 kWh to further simplify things.
So you need to recharge 10kWh every day. Assuming you’re still near Worchester, MA, NREL says you get about 2.87 to 5.60 kWh/m^2 per day of sun depending on the month.
NREL assumes the panels are 16% efficient. 10 kWh / .16 = 62.5
Then you need to account for losses converting DC to AC. NREL assumes 77%. 62.5 / 0.77 = 81.17
81.17 kWh per day / 2.87 kWh per m^2 per day = 28.29 m^2.
So you’ll only need about 30 square meters of panels, which is about a 3 kW array. Here’s what that might look like; it’s not insanely large. This crude calculation roughly corresponds with the NREL calculator linked to above (input a 3kW system for your location and you get about 3662 kWh per year, or about 10 a day), but is way off from Stranger’s math… I think maybe he didn’t take panel efficiency into account? 13 m^2 seems small for a 53kWh/day system.