Does solar work in Michigan winters?

It is the first question almost everyone asks, and it is a fair one. We are on the wrong side of a lake that manufactures clouds, and in late December the sun is up for about nine hours.

The short answer: yes, it works, and no, December is not the month to judge it by.

Solar is annual, not monthly

A solar array in West Michigan produces a large surplus in summer and a deficit in winter. That is not a flaw in the design, that is the design. The crediting structure and your utility bill both operate over a year, so the number that determines whether a system was worth buying is the annual one.

A typical West Michigan array produces something on the order of four to five times as much in June as it does in December. Your July production carries your February. When we model a system, we are modeling twelve months, and the monthly shape is something we show you so December is not a surprise.

Cold is good for panels

This surprises people. Photovoltaic modules are more efficient at lower temperatures. A module’s rated output degrades as the cell heats up, which is why a brilliant 92 degree August afternoon is not the peak performance you might imagine.

A clear, cold, sunny February day with snow on the ground reflecting light is genuinely excellent production weather. The limiting factor in a Michigan winter is daylight hours and cloud cover, not temperature.

Snow

Snow on modules stops production. There is no way around that. What matters is how long it stays there.

Panels are glass, they are mounted at a tilt, and they warm slightly as soon as any light reaches them, so accumulation usually slides off faster than the snow on the roof around it. A storm that leaves snow on your roof for a week will typically leave snow on your array for considerably less than that.

Do not go up and clear them. A roof in January is genuinely dangerous, and a squeegee or a rake will scratch glass and can damage the module frame or the flashing. The production you recover is not worth the risk to you or the equipment. We model your production with winter losses already included, which means the array is expected to pay for itself with the snow days in the math.

Lake effect and what it does to a model

West Michigan gets meaningfully more cloud cover in November through February than the state average, and the effect varies by how far inland you are. This is one of the reasons a production estimate pulled from a national average is not good enough here.

We model against local irradiance data and the actual geometry of your roof: tilt, azimuth, and the shading from your own trees and neighbors across the whole year, including the low winter sun angle that puts shadows in places they never reach in July.

A south-facing roof at a healthy tilt is the best case. East and west facing roofs work, they just produce differently, and the model tells us how much. We have put arrays on both.

What good winter design looks like

• Tilt and orientation chosen with the whole year in mind, not just the summer peak.
• Shading modeled at the December sun angle, which is far lower than most people picture.
• Racking and attachments rated for local snow load, flashed properly so a freeze-thaw cycle does not become a leak.
• Module-level monitoring, so if one module underperforms in March you know it is a hardware problem and not just the weather.

The honest caveat

Michigan is not Arizona. Our arrays produce less per installed kilowatt than the same equipment would in the southwest, and any Michigan installer who tells you otherwise is not being straight with you.

What matters is not how Michigan compares to Arizona. It is how your annual production compares to your annual consumption, at the rate your utility charges. That is a calculation we will run on your actual roof, and we will tell you if the answer is no.