Does it pay for SCE Homeowners to wait to get solar? ​Since solar technology is still improving each year, and since prices continue to fall, maybe it makes sense to wait for a few years to get a better system for less money. Here is a cost comparison for a typical SCE homeowner between getting it now or waiting for a year.

Actually, it doesn't make sense. Quality and efficiency of PV systems is likely to improve only gradually from now on. Prices have already fallen by 73% in the last nine years (about 7% per year), but are likely to fall slowly from now on, partly due to the phasing out of state tax incentives and utility rebates.

But suppose prices do continue to fall by 7%/year. For the SCE-customer homeowners we use throughout the site as an example, paying an average of $200 per month to SCE, assuming all the best choices for everything and taking all factors into account as before, what difference would this make?

If they postponed getting solar for one year, their net PV system costs over 20 years would decline by $540 to $1,760, depending on type of financing. But they'd lose about $1,900 in 1st-year savings. So waiting doesn't pay.

The ITC is scheduled to remain 30% through 2019 but will go down to 26% in 2020, 22% in 2021, and disappear in 2023. It represents a discount of about $7,000 on our homeowners' system, so it would be a shame to wait until that is reduced or no longer available. There are no California state income tax credits for solar.

Another reason to get solar sooner rather than later is possible future changes to electricity rate structures, such as changing the time of use periods for on-peak, off-peak, and super-off peak rates to reduce savings for new solar customers.

Solar is a great deal right now. Who knows how this might change as adoption rates soar in the future, as they are widely predicted to do? The only reason to wait would be if there's no way to afford it now.​