We all love solar, but I’m a little concerned with a trend I see here in Vermont lately—too much solar going up in beautiful farm fields, and not enough going up on people’s roofs. It’s no mystery why this is happening—it’s cheaper to install arrays on racks in open fields than to install them in any other configuration. Though the price of solar panels is steadily dropping, the profit margin for arrays like the one in the image above is still thin, despite favorable federal and state tax policies. The arrays wouldn’t pay off for investors if the costs of installation were much higher, and putting arrays on rooftops can be complicated and expensive.
I’m on the board of directors for the Acorn Energy Co-op in Middlebury, VT, and we’ve been struggling with this issue. Despite a strong preference among the board to support rooftop arrays, it’s been very difficult to get large rooftop projects past the planning stages. The problems are myriad. As opposed to a flat field, every rooftop is different, so projects must be individually designed. Labor costs of these projects are higher, as well, and all involve rooftop penetrations, a potential source of leaks.
Our group has tried multiple times to support projects on the largest roofs around—dairy barns. These huge, flat, slightly-angled roofs nearly scream for solar installation. But, we’ve found that most of these types of buildings haven’t been designed to support any additional roof weight beyond code-required snow and wind loads. As such, insurance companies won’t insure the projects. The difference in weight requirements is so small as to be almost laughable– in most cases a few extra pounds of dead load per square foot. These building are usually built with trusses, and the trusses are computer-designed for each building to be only as strong as required. With prior planning, most roofs could be made stronger, during construction, for a tiny percentage of the roof cost. (We’re currently working with structural engineers and roof truss suppliers to get actual cost figures). However, to retrofit existing roofs costs enough to derail most of these projects. The whole situation reminds me of that old nursery rhyme, “For the want of a nail the shoe was lost…”
Other factors also push the projects onto open agricultural land. First, there is often tremendous opposition to the cutting of trees, either from the landowner, or neighbors, which makes open areas more suited than wooded ones. Then, a whole host of laws prevents development on wetlands (for good reason), so potential sites must be dry. Then, if the soil is too rocky and doesn’t support digging, then that too incurs extra costs. So, when all is said and done, the arrays usually end up sited in farm fields. This isn’t catastrophic—we’re going to need a lot of solar, and the arrays don’t permanently damage the land. When their lifetime usefulness is past, the posts can be pulled and farming could recommence, or the land could revert to an undeveloped state. But if we’re not careful, there’s going to be a public backlash against solar. It’s by far the most promising technology we have to avert climate change and shift our paradigms around energy use, so we can ill-afford such pushback.
So, my personal opinion here—it would be better to utilize all those big empty roofs. Barn roofs, warehouse roofs, school roofs, the roofs of big-box stores, the space above parking lots, the roofs of every house… We need to change building codes to require the few extra pounds of load carrying capability that solar arrays would add, and we need to raise awareness about the future value of such rooftop space, so as to encourage roof designs that support future solar installations. Those things alone won’t solve the problem; I’m not sure how to completely change the economics that make arrays in agricultural fields more profitable. But, we might need to refine our mindsets with regard to solar installations. Rooftops first, please.