Duluth man builds, sells, solar heating window blindsby Bob Kelleher, Minnesota Public Radio
Duluth, Minn. — The next big product for green energy might not come from a high-tech laboratory. It could be from a next door neighbor tinkering in the basement.
A Duluth area man is hoping he's come up with the next big thing. He's selling a heat-collecting window blind he rigged up at home.
Keith McKenzie was wondering, what if he could capture the sunlight coming in the windows and turn that into free heat? He came up with a system that looks like vertical window blinds, but the blinds are hollow and clear on one side, and they have a black strip of aluminum inside.
"Sun comes through the south window, hits up the high absorbing metal, and hot air naturally starts to rise," McKenzie said as he showed how the blinds work. "You can see where it's open on the bottom. It draws in cool air off the bottom; pushes out warm air on the top. Very simple.
McKenzie says one of the key innovations his solar panel brings to the marketplace is its location -- indoors.
"Every solar heater on the market is outside your house. And when it's 22 below outside, that heater starts at 22 degrees below zero," McKenzie said. "When the sun comes up in the morning ... with this one on the inside of the house, this one starts at about 60 degrees."
If you think Keith McKenzie sounds like a used car salesman, he is. He's senior partner at one of the region's biggest car dealerships, in Two Harbors.
But a few years ago he was in the solar energy business in the Twin Cities, selling things like solar collectors.
"I never quit playing with solar heating since that time. It became a little bit of a passion," he said.
Two years ago, he hit on the window blind heater. He got a patent, formed a partnership, and started making them in Chaska. Now he's getting inquiries from potentially big customers like motel chains.
"The inquiries are coming from the senior health care area. They're coming from schools. They're coming from homeowners. They're coming from motels. I've talked to a couple that are motel chains. The interest is coming pretty good," said McKenzie.
The heaters, sold under the name of SolarChoice, got a positive plug recently on Bob Vila's remodeling blog.
SolarChoice heaters hang in the windows of McKenzie's Grand Lake home near Duluth.
The cost varies by size, with a 6-ft. wide patio door size running about $1,300. Payback will vary, depending on things like how much sun reaches a particular window. And the efficiency is still under scrutiny.
The SolarChoice Web site says the heater can reduce heating fuel consumption by up to 35 percent. But that performance claim is still being tested. McKenzie is contracting with the University of Minnesota, Duluth Department of Engineering for a more precise study.
Last January, professor Richard Lindeke got his first look at the SolarChoice blinds.
"I was not a believer when I first got involved with this," Lindeke said.
After all, the sunlight's already coming in the window, and who in northern Minnesota would want to shade their south-facing windows?
But, Lindeke explains, the blind system might provide some degree of heating benefit, because it moves air away from windows that lose heat. He says the blinds might provide more heat than a passive system, like putting bricks in a room to absorb heat from sunlight.
"So there is a potential for 3 percent to 5 percent better recovery with these systems over a passive system. We don't know the answer to that," he said.
There's also something Lindeke calls the shadow effect, where these heaters could continue to pump out heat some time after the sun disappears behind a cloud, or sets at night.
The jury is still out on just how much energy they really save. Lindeke is overseeing a better controlled experiment this winter in a pair of small buildings that sit side by side on the campus farm.
Meanwhile, Keith McKenzie continues his scheming.
"I would like to find a little wind thing that the average home owner can have, and I've got some stuff on the drawing board," said McKenzie. "I'm not going to quit playing with these things."
The long-term success for SolarChoice heaters might hinge on university tests this winter, to figure out just how much they can really cut off a heating bill.
- All Things Considered, 11/30/2009, 5:20 p.m.