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minneapolis solar array on garage

1. What Is the Solar Potential of the Site?

The garage site has a clear path to the sun at all times of year – an oasis of direct light in a historic neighborhood otherwise well-shaded by towering elms. Only a utility pole and its web of radiating lines would cast shade on the panels.

2. What Are the Design and City Code Issues with Solar Panels?

I worked with the architect to orient a broad expanse of south-facing, smooth roofs. Given the simple rule of thumb that when mounting panels, they should be at an angle equal to your geographic latitude, we aimed for a 45-degree roof pitch. City code dictated the pitch of the garage to be equal to the house, which is a 10:12 pitch, or about 40 degrees. Close enough. At this pitch, the panels would err on the side of slight over-performance during summer and under-performance during winter.

3. What Solar Panel Connectivity Concerns Are There?

With a detached garage, the placement of meters and other hardware got complicated. My electric utility required a new bi-directional meter that can turn backward when I generate more electricity than I can use. They also installed a solar production meter that calculates how many kilowatt-hours I produce so that they can pay me for the energy via their Solar Rewards rebate. We had to install a DC to AC inverter and emergency shut-offs at both the house and the garage. This caused us to dig a shallow trench to run the DC electricity from the garage roof to the constellation of meters on the side of the house. As unsexy as it is, this work amounts to a majority of the project cost and is required whether you put up one panel or (in my case) fourteen panels. So, economies of scale are pretty real with residential solar projects. 

4. How Best to Choose an Installer and Solar Panels?

After getting three bids, one installer stood out as being best suited for my project due to their extensive experience and level of comfort with small, residential jobs and their track record of being very attentive to customer concerns. When you deal with products of a 30-year life span, you want to buy a product from a company that will still be around in 30 years. I’ve watched two Minnesota-based solar manufacturers flourish. But then go out of business, leaving their customers without recourse, should their panels have any troubles. I chose to go with a Korean manufacturer that is a very diversified company and has less likelihood of going out of business during the lifetime of my panels.

5. What Are the Economics of Solar Panels?

In just over three months of use, the panels have generated 2.01-megawatt-hours of electricity. At Xcel’s rate of 11.9 cents per kilowatt-hour, that translates to about $240 of savings on utility bills, with the sun’s harshest months just ahead. At this rate, and from my initial analysis, I anticipate the electricity savings paying for the upfront investment in about six to seven years.

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