Walker Energy Systems

I just learned from the Tenney-Lapham Neighborhood Association newsletter that a MadiSUN client has installed a 5.8kW solar electric system. I did an assessment for Patty Prime and Richard Linster last fall. Their house had good solar potential and their electrical consumption was already pretty frugal, so they were great candidates for solar.

And this spring they decided to go for it. Their house (like many on the isthmus) sits at 45º to due south and is hip-gabled, so they were able to put up 25 PV panels by utilizing both the southwest and southeast sides of the roof. They will be able to meet 100% of their electrical needs and still sell several thousand kilowatt-hours a year back to MG&E!

You can see a photo and  read a nice article from the TLNA newsletter here.

On June 3rd, Mayor Dave Cieslewicz formally announced the MadiSUN program. This program, funded by a Dept. of Energy Solar American Cities grant, has the goal of doubling the number of solar energy systems in Madison by the end of 2009.

A major component of the grant is to provide the community with a consultant who can help interested residents and businesses install a solar system. The consultant can provide technical expertise and answer questions regarding design, permitting and rebate programs. The service is provided at no cost to the resident or business.

And the winning bidder for the contract to provide these consulting services was Walker Energy Systems. I have already talked to several dozen individuals and businesses who are interested in solar energy, giving them detailed information about the costs and benefits, discussing their buildings’ suitability for solar power, and performing site visits to measure the “solar window” over their property for shading or other issues.

If you are a resident of Madison and interested in learning whether solar energy can work on your home or business, you can get started by simply sending an email to solar@cityofmadison.com with your name, address, email and phone number, plus some good times to contact you.

I will first call you for a brief conversation to discuss your interests and give you an idea of the costs and payback. If solar seems like a good fit for your property, we can then schedule a site visit to measure your property’s solar window. I then provide you with a report outlining your property’s potential and with a financial analysis spreadsheet on cost and payback projections.

The MadiSUN program gives Madison residents a quick and easy way to get up to speed on solar energy and find out how well solar energy would work on their property, at no cost to them. You can get more information about the program on the City’s MadiSUN web page.

I’ve found that the most interesting aspect doing solar assessments is that they frequently remind me of the importance of asking the right question in the first place.

Consider a solar PV (electric) assessment I did for a homeowner in rural Dane County. The home is a passive solar design from the ’70s, with two stories of south-facing, floor-to-ceiling windows and a substantial amount of tile flooring to absorb heat all day. It has two backup heating sources: a wood-burning stove and some electrical resistance heating recessed into the floor in front of the first-story windows. The house is on-the-grid for electricity, but has no natural gas or LP supply.

The homeowner described their heating situation as primarily passive solar, with a fair amount of wood-heating, augmented with some electrical heating. Sounded like a pretty good design…

As always, the first thing I did was to download their utility records for the past couple of years. If you haven’t done this for your own home, I strongly recommend it: MG&E has a great on-line service that gives you tables and graphs of your energy consumption, and lets you download the data for further analysis. The first step to an energy-efficient home or business is knowing how much energy you use and when.

As soon as I looked at the numbers, I realized that the homeowners’ description of their heating strategy didn’t exactly match the data. Their modest-sized house was using over 15,000 kilowatt-hours per year, nearly double the state average and triple what I typically see for houses of similar size and age!

Of course, being an all-electric house meant that they did have to cook and dry clothes with electricity, but 15,000 kWh/year is still a lot of electricity.

The owner was a bit puzzled at how high their electrical consumption was, as he knew they burned quite a bit of wood and the house was, after all, a passive solar design that generally felt pretty comfortable except during long spells of especially cold and cloudy weather.

A key step in any solar assessment is to measure the building’s “solar window”. The amount of solar energy available to be collected on the roof of a building depends on a number of variables. Some are determined by the latitude and climate of the location (how long the days are, how much cloud cover the area has in a typical year). Others are specific to the building itself (the slope of the roof, the direction it faces, any shading from surrounding tress and buildings). I use a special camera system that photographs the sky from east to west, and then use software that takes the photos and computes the amount of solar energy available in a typical year and the amount that would actually reach a collector on the building’s roof.

And that’s when we learned the punch line to the story: When the house was built 30-odd years ago, they had planted a row of pine trees as a wind-break and privacy screen. The trees are a considerable distance to the south of the house, but had obviously grown quite a bit over the years. The solar window analysis showed that the trees had grown so tall that they were blocking the sun during most of the middle of the day (prime solar heating time) during most the the mid-winter months!

So the data showed, to everyone’s surprise, that they really had a wood- and electrically-heated house with a passive-solar assist. We had started out trying to see if solar PV panels could help reduce their electric bill, when the real issue was trees impairing their passive-solar system.

I also noted that a number of the south-facing windows showed signs of fogging, indicating that the thermopane windows had lost their vacuum. This meant that they were letting less sun in and more heat out than they had originally.

So my assessment report advised that, Yes their roof could be a suitable location for solar panels. But the highest priority improvement in which they could invest is to restore the passive solar design by trimming the trees and replacing the failing windows!

I love the idea of generating carbon-free electricity on the roof as much as the next person, but as a solar assessor my job is to give homeowners objective, factual advice about how to get the most benefit for their investment of time and money. It doesn’t make sense to invest in expensive solar PV panels, and then throw the electricity away through leaky windows. First things first: doing conservation measures first, then adding renewable energy hardware is almost always the best policy…