Comments on: New Solar Module Reduces Payback by up to 5 Years

By: Steve C. Yang, P.E.

Steve C. Yang, P.E. — Fri, 03 Aug 2012 01:20:00 +0000

A word of caution, all these pay-back estimates are based on ‘perfect’ operation through-out the year! It is NOT the case for many! Things can go wrong in PV arrays. Owners and operators should check up on their arrays periodically. Free analytics is available at http://www.pvwizard.com. Check it out.

By: Zachary Shahan

Zachary Shahan — Tue, 31 Jul 2012 23:29:00 +0000

Wow, that’s awesome! What model?

By: Zachary Shahan

Zachary Shahan — Tue, 31 Jul 2012 23:29:00 +0000

So. Cal: likely

Does that improve performance?

By: Bob_Wallace

Bob_Wallace — Tue, 31 Jul 2012 22:14:00 +0000

US average rooftop solar installed $4.44/watt, first quarter 2011 so less now. But let’s go with the older price.

Southern CA with an average of 5.5 solar hours, 23% capacity factor. 1kW of panels * 5.5 solar hours * 365 days = 2008 kWh/Yr.

2008 kWh @ $0.25/kWh = $501.88. A kW of panels would be offsetting a $501.88 electricity bill for the year.

$4,440 financed for 5 years at 6% = monthly payments of $85.84 or $1,030 for 12 months. Pay older ‘full price’, pay off in five years, and you get to break even in less than ten years.

But take off the 30% federal subsidy and the $0.65/W SCE subsidy and the price drops to $2.65/W. $51.23 monthly payment or $614.76.

So it looks to me as if the subsidized price of rooftop solar is getting pretty close to a five year payment. Perhaps all the way there with more current installation rates.

Open Neighborhood, an LA community installation program has been reporting $2.78/W installed prices. Clearly they’ve hit a five year payback when you include subsidies.

Oh, if you assume $0.25/kWh and 3% inflation over a five year period then you should be using an average grid price of $0.27/kWh. Over a ten year period utility power will average $.29/kWh.

By: Anne

Anne — Tue, 31 Jul 2012 20:59:00 +0000

Is your house located close to a body of water?

By: Dcard88

Dcard88 — Tue, 31 Jul 2012 01:32:00 +0000

This reads like sales propaganda 101. I would want to see specs if I were considering a system. I am still waiting to see anything close to a 5 year payback, and thats in CA where the rates are .25 per kW +++. I would challeng anyone to prove a 10 year payback if your rates are below .18 per kW. Cos that quote 12 year payback for Resi are usually best case scenario, meaning no shading ever, and assuming rate increases of 5% annual..

By: Bob_Wallace

Bob_Wallace — Mon, 30 Jul 2012 23:52:00 +0000

So, Joshua, what’s the cost per watt?

Are these folks dropping prices below $0.75/watt or are they just writing copy? Perhaps they’re making a lower BoS claim due to higher efficiency?

Self cleaning is interesting, but many arrays are never cleaned now so there’s little to no savings coming there.

By: Bob_Wallace

Bob_Wallace — Mon, 30 Jul 2012 23:49:00 +0000

These products promise to “further reduce” “up to five years”. That would make the 5 and 3.8 periods shorter (but almost certainly not 5 years shorter ;o).

Rule of 72. A five year payback/payoff is a 14.4% return on investment. A 3.8 year payback is a 18.9% return on investment. A 3 year payback is a 24% return on investment. Fixed and guaranteed.

Just try to find that sort of investment opportunity available for us mere mortals in the real world.

The best current money market rate for $10k+ accounts is 1.05%.

If you borrow the money to install at 12% you’ll still be making the spread between 12% and [14.4% to 24%]. And then enjoying many years of free electricity.

What’s not to love?

By: Paxildog2004

Paxildog2004 — Mon, 30 Jul 2012 23:00:00 +0000

Payback in So. Cal. for my system is about 3.8 years since it functions at 142% of design for some reason. I won’t argue.

By: John Jay Gebhardt

John Jay Gebhardt — Mon, 30 Jul 2012 12:35:00 +0000

Payback periods are already at 5 years. In the Caribbean it is 3 years.