This thermal storage system uses a massive tank of water to store energy from the sun. Alaska receives abundant sunlight during the summer but very little during winter months, when heating loads are greatest. Thermal storage allows us to capture heat with solar collectors in the summer and tap into it during the heating season.
In 2013, we installed 16 solar thermal collectors on the south roof of the building and buried a 25,000 gallon water tank in the ground. The solar collectors transfer heat into the tank in the summer through a heat exchanger, and the building draws from this heat in the winter. The system can produce 50 million BTUs a year, or the equivalent of 400 gallons of heating oil. This demonstration provides clues about how to design a residential thermal storage system and the potential costs and savings for homeowners.
This experimental solar seasonal storage project was funded by a $70,000 grant from BP Alaska, which includes solar hot water collectors and a heat storage system to enable solar energy to be stored and used during the winter. The tank was donated by K&K Recycling.