100 MW * 8760 hours/yr = 876,000 MWh/yr<br /><br />150 MW * 8760 = 1,314,000 MWh/yr<br /><br />Now, 150 MW/100 tons is 70 watts per lb, which is spacecraft typical power density. <br /><br />At $0.15/kwh, this generates $131,400,000 per year. <br />At $0.20/kwh = $175.2 million/yr<br /><br />Assuming a ten year life, this is $1.75 billion in lifetime revenues at 20 cents/kwh. Given the launch cost alone is $1.6 billion, not counting the cost to build the SPS, it still is not cost effective to launch SPS'.<br /><br />If you are generating 150 MW, your revenues are $2.63 billion over 10 years.<br /><br />Assuming a $1.9 billion launch cost for 100 tons to LL1(200,000 lbs, at $9,500/lb launch cost, which is how the SeaDragon numbers scale for inflation), and assuming SPS production cost of $5.00/Wp and 10W/kg power density, the SPS will cost $50/kg or $22 million delivered to the launch site. This is based on earthbound solar panels, though. Going with GaAs multijunction technologies, and spacecraft type construction, a closer price is $5,000/kg, or $2.2 billion. Assuming no hiccups in deployment (and automated deployment), this is $4.1 billion.<br /><br />Assuming a 5.5% finance rate (utility bonds) this is about $7 billion total capital costs for a 10 year payback.<br /><br />Now we can also increase the electricity rate at the rate of inflation, averaging 3%/yr, this ups the 10 year revenues to $2.06 billion, still way short of paying back the investment. You would need 30 years to earn $8.575 billion, and still owe $7 billion. <br /><br />Essentially you'd need electricity prices in the range of $0.30-0.40/kWh to make this investment pay itself back.