New solar array technologies (e.g. ROSA, FAST, Ultraflex) could provide the power for a high-‐power SEP stage (with specific powers of 130-‐220 W/kg).
Space Solar array technology has been doubling every four years.
There are other potentials for more radical improvement in space capabilities, but this incremental scaling up and improvement of what has already flown in space.
The Japanese Ikaros satellite, a solar sail, is producing power at about 0.8 kg/kw [1250 watts per kg, 5 to 10 times better than what the SEP stage can do) for the power production system. This extremely low value is accomplished by using a heliogyro thin film solar sail design, which has no structure, and thin film solar cells on part of the surface. Given reasonable improvements in thin film solar cells this figure could be 0.16 kg/kw [6250 watts per kg or 28 times better than the 220 watts per kg expectation for 2020] for power production, not including other parts of the satellite.