Solar Hot Water and Solar Electricity Cut Costs for Bozeman Affordable Housing Project

This fall, the first residents will move in to the brand new 136-unit Larkspur Commons affordable housing development in Bozeman, serving residents earning less than 60% of the area’s median income. They may not know it yet, but two types of solar energy systems will reduce utility costs at their new home. Larkspur Commons is being built to include both a 4,000 square foot solar hot water system and a 12.42 kilowatt solar electric array on its roofs.

Larkspur Commons is owned by a partnership that includes Homeword of Missoula and GMD Development of Seattle. According to Steve Dymoke, Vice President of GMD Development, the decision to incorporate solar into the project was primarily about cost savings. In order to take advantage of a federal low income housing tax credit, they must retain ownership of the property for at least 15 years. As Steve explains, “Rents are restricted as part of the program but our operating costs are the same as a market rate developer, so we’re very focused on operating expenses and controlling costs in the long term. Solar is a cost-saving measure over the 15 year time horizon, particularly in a sunny place like Bozeman where even in the winter we’ll be generating a significant amount of electricity and hot water to offset our operating costs.”

Liquid Solar Systems is installing the solar hot water system at Larkspur Commons, and Onsite Energy is installing the solar electric system. Both are Bozeman-based businesses. Todd Hoitsma, owner of Liquid Solar Systems, explains that the project includes 16 separate solar hot water systems, each feeding 6-9 apartments with pre-heated water for each apartment’s own water heater. Overall, the capacity of the system is a whopping 5.6 million BTU/year, which Todd calculates is equivalent in energy terms to a 165 kilowatt solar electric system.

Solar hot water is a great fit for large multi-family developments like Larkspur Commons, Todd says. “Commercial projects like this with a high and consistent demand for hot water maximize the efficiency of solar hot water systems. Each solar hot water system on this project will operate in the 55-70% efficiency range, which is much higher than many residential solar hot water systems, not to mention solar electric systems.”

The solar electric system at Larkspur Commons will provide power to common areas such as a community room, kitchen, and outside lighting.

Roof space was a challenge for the solar installers. South-facing roofs are ideal for solar, but there wasn’t enough south-facing roof space at Larkspur Commons to accommodate all of the solar panels. Orion Thornton, co-owner of Onsite Energy, explains, “We had to really coordinate on the available roof space. We ended up putting the PV panels on a west-facing roof because the much larger solar hot water system took up all of the south-facing roof space, and some of the east- and west-facing roof space as well.”

In addition to solar, Larkspur Commons is being built to incorporate a number of energy efficiency measures including energy efficient windows and good insulation. According to Steve, “For the residents, the benefit will be a real comfortable year-round living environment and lower utility costs.”