This project seeks a solution that improves the performance of a small-scale, off-grid, photovoltaic system based in a family home. The solution could have potential broad application for off-grid homeowners. Michigan sun exposure is a story of feast and famine – this home seeks to enhance their system by effectively storing some of the system’s summer electrical surplus for use during the short and cloudy days of winter.
The system consists of a dozen 250w Sun Power panels on a 25′ tall dual axis, heliotropic tracker. Power is currently stored in 60 golf cart batteries and uses an 8kw inverter for daily use. The family is adept at modifying behavior and power use during the season variations. Their daily use ranges from as little as 4kw in the winter to more than 20kw in the summer. When sunless days stretch past 3 or 4 days in the winter, a small generator is used to charge batteries while they wait for the return of the sun. In Winter 2013, 30 gallons of gasoline were used. The client wishes to eliminate the use of the generator / gasoline and expand power availability in the winter. Many summer days, the batteries are at full capacity early in the morning and since they are off the grid, surplus power goes unused. This project seeks solutions for taking that surplus and storing it for use in the winter months. Possible solutions could include wood gas, fuel cell / hydrogen or even kinetic energy.
A&D Professor Joseph Trumpey