Due to lack of funding, the state of Minnesota had to turn away nearly 50,000 households who applied for fuel assistance and qualified in 2006. Since then, funding has expanded with numerous experimental programs underway on both the energy assistance and the weatherization front.
The Minnesota Renewable Energy Grant program assists weatherization agencies throughout the state with installation of renewable energy equipment, including solid fuel furnaces and solar hot air units, on low income homes. Open to all 32 weatherization agencies in the State, the Renewable Grant pilot program launched at the end of 2007. Nine agencies have participated so far with $134,957.00 awarded to date. The pilot program produced pay-back calculations and solar site analysis for 30 single family homes in the past year. This grant has installed solar air heat systems on 30 homes to date, at an average expense of $4,500 each.
The technology installed with this pilot program is a solar powered furnace (SPF), using Minnesota based manufacturers and local contractors. The furnace is developed by the Rural Renewal Energy Alliance (RREAL) and uses state of the art passive solar air technology. By delivering solar heat to low-income families on public energy assistance, RREAL endeavors to make solar energy accessible to people of all income levels.
Innovations in the RREAL SPF make it more durable and higher performing than earlier solar air heat technology. The SPF is made of glass and aluminum and incorporates an air-tight interlock system that allows multiple collectors to be connected in serial fashion. On the back of the panel, an extrusion rail mounting system is designed to make the panels easy to install. The panels come is three sizes with the largest, 4’ x10’, as the most popular.
A solar air heat system can eliminate the need for a considerable portion of a household’s winter heat fuel use. A glass front panel traps heat as its ultra clear, low iron surface has an excellent transmittance property of 91.8%. The panels work like a greenhouse with a dark painted interior metal plate absorbing heat. The selectively coated aluminum absorber plate has an absorbtivity of .933 and an emissivity of -.49, the best available for solar thermal uses. The high performance air flow design behind the absorber plate results in maximum heat scrubbing for the air. The airtight connection system reduces the size of the fan needed to move air from the heat absorption panel to the home’s interior.
The program grant paid for site visits–which normally cost a $250 fee– to determine whether the candidate homes had adequate south facing facades. In addition, site analysis fixed the location of the inlets for heated air and the outlets for cool air, as well as the location for the fan and the availability of adequate electrical service for the fan. System design must include two 4’x10’ SPF collectors, three 4’x6.5’, or three 4’x8’collectors. Side by side installation in which the panels are parallel is preferable. If the home is very small, exceptions are made for fewer collectors. A typical large home with adequate sun hours is fitted with three 4’x10’ SPF collectors at a cost of $3,900. Mounting and balancing of the system cost $1,000. Installation and wiring of the system costs $3,000. About $700 in miscellaneous expenses brings the total system cost to $8,600. The 30% federal tax credit lowers the net total cost to $6,020. The payback period depends on numerous variables. A household might save $200 per month in the heating season, producing a payback within five years. The SPF collector systems are built to last fifty years. A small home system with two 4’x6.5’ SPF collectors comes to a net total cost after tax credits of $3,780. A large commercial building with eleven 4’x10’ SPF collectors comes to a net total cost after tax credits of $23,855.
The pilot program benefits includes the staff learning how to incorporate renewable energy technologies into existing homes, gain installation skills in different settings, and monitor home energy consumption and savings. The program involved low-income homeowners in each stage of the work and educated them about energy use. Favorable local media attention from the SPF installations helped develop community awareness of energy self-sufficiency and expand the potential partners and funding sources for local weatherization agencies.
Posted on: September 8th, 2011