The reason for this? Simply that the renewable market is growing rather rapidly and the price of renewables are declining. With existing infrastructure in conventional plants, if you add enough capacity that you end up retiring the most expensive 2-5% of your conventional generation every year, it makes a huge impact on pricing.

Even if the price of every source rises consistently from year to year, as you trim off the most expensive production methods, the end price will stay fairly stable…

Add in the fact that roof-top solar is almost at grid parity in most of these places (if it’s not already there) and I just don’t see prices going up substantially…

In the United States, 99% of solar photovoltaic installations were net metered, signifying that net metering in the United States is preferred by far over the alternatives, which are off-grid solar and on-grid but not net metered solar.

http://cleantechnica.com/2013/04/19/99-of-2012-us-solar-pv-installations-were-net-metered/#3xOtWxcB3GettUgq.99

Currently, 43 states plus D.C. have implemented net metering policies. While many states have adopted net metering, types of NEM policies vary significantly by state. Vote Solar put together an index that grades each state by the effectiveness of their respective NEM policy.

http://www.seia.org/research-resources/net-metering-state

A lot of those states get a grade A or B. (Of course it’s easy to guess where the F states are located.)

Solar prices, including installation costs, are coming down. Panel prices are expected to drop by one-third in the next three years.

The western world is recovering from the 2008 economic crash. There’s more money to spend on getting solar on rooftops and less anxiety causing people to avoid investing.

Concern about climate change is growing.
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I would expect we would see end-user solar installation rates highest in areas with the highest retail electricity rates. The New England and Middle Atlantic states have higher than average electricity costs which makes solar a good investment even though they might get a bit less sun (annually) than Southwest states.

Look at how much solar New Jersey has installed.

http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a

I question whether grid prices will rise that fast. What we’re seeing in places that have installed a lot of renewables (solar in Germany, wind in Texas) is that it’s making electricity cheaper or at least dampening the rate of price increase.

A lot more solar on US grids will cut the amount of expensive peaker power used and lower the merit order price ceiling across the board. Just removing a little demand can have a very large effect on peak settling price.

Another point is that the US average LCOE is not very useful. Electricity markets are state not federal, and insolation varies regionally. So with grid parity already there in the Southwest, you’d expect mass adoption starting there and spreading E and N. I’d add that without the cost-of-capital number for LCOE, which depends on public policy and financial intermediaries, you can’t evaluate the estimates.

Also battery storage technology is improving exponentelly. And battery storage technology makes roof-top solar very attractive and significant player.