Sunday, October 11, 2009

Rooftop solar as the low-cost alternative: An O'ahu example

O'ahu resident and Realtor Tony Kawaguchi started with the low-hanging fruit when he looked for ways to cut down a $625/month power bill in September 2008.

(Images: Top: Solar photovoltaic panels on Kawaguchi's roof. Bottom: “This is the Sunny Boy converter, installed by Mercury Solar. The installation took about 4 hours, and sits next to Hawaiian Electric’s meter, which now spins a lot slower than it used to,” Kawaguchi said. Credit: Tony Kawaguchi.)

He said he changed incandescent light bulbs to compact fluorescent bulbs, which use a quarter of the power for roughly the same amount of illumination. He dropped the temperature on his water heater. He retired one of his three computer monitors.

It didn't create the level of savings he was hoping for. Then he went upstairs.

Kawaguchi put a solar water heater on the roof, essentially removing his electrical cost of heating water.

And he then installed a photovoltaic system.

The electric bill was cut in half in the first month. Kawaguchi has since expanded his photovoltaic system to reap more savings. His bill was $153.47 in September 2009.

Kawaguchi said he was able to make the adjustments with very little cash outlay. He found a solar contractor with a program that financed the cost of the system at 2 percent interest. And he took advantage of a state 35 percent tax credit and federal 30 percent tax credit.

Additionally, Kawaguchi took advantage of a program under which he claimed the tax credits for paying to install solar water heaters on the roofs of low-income residents.

“I also bought another solar water system for a low income family on which I also receive the 65 percent tax credit, but the solar company finances nearly all of it at percent, and the low income family pays the loan off. So I receive the 65 percent tax credit on that $7k system, but don't have any cash out of pocket,” Kawaguchi said.

“So in reality - I paid NOTHING for all my solar power. I simply took money that I would have paid the government and instead purchased enough solar energy for other people to receive tax credits to pay for it all... I had my CPA look at it and he was already familiar with this type of deal through other solar companies,” he said.

Kawaguchi, who blogs on real estate at, said that from a real estate perspective, these changes make good economic sense.

“Imagine if you were a buyer comparing two similar homes in Hawaii, and one of them allowed you to have almost no power bill. That monthly savings would be a huge factor in the value you would see in that home,” he said.

© Jan TenBruggencate 2009


zzzzzz said...

Kawaguchi sounds like a candidate for an energy audit. Even after installing PV, his bill is higher than an average home.

Tony in Hawaii said...

@ zzzzzz

you must not live in Hawaii. our power bills are very high here. Plus my home is 3000sqft in a hot area.

zzzzzz said...

@Tony, I do live on O'ahu, so I'm paying the same rates as you.

According to, the 6.2% rate increase in 2009 would cause the typical customer to pay $7 more per month, from which you can easily determine that the typical customer bill is about $120 per month.

My last bill was very close to typical. Your bill, by contast, is higher than that, even after PV installation. Before PV, your use was about 5.5 times that of a typical customer.

This, along with your willingness to try to reduce your consumption, is why I think you're a good candidate for an energy audit. I find it hard to believe that there aren't a lot more low-hanging fruit that you haven't picked yet.