Possible.. interesting thing to note is that home owners are more inclined to lease panels than buy them (so retail cost doesn't matter much it appears). SolarCity really took off after it started offering the 0 down lease. If that trend continues, Tesla could potentially offer a blanket $x/month for energy production and $y/month for consumption (cars) and lock people in. We know panel cost and batter cost will go down over time, so the game is likely in selling experiences not entities..