Solar Thermal or Water Heater Efficiency?

Max Twogood for Zondits, August 3, 2015. Image credit: Avalanche Energy

[Somerville, MA] Avalanche Energy is a small start-up with a new take on a century-old technology. While they are based just outside of the snowy city of Boston, Avalanche has nothing to do with this frosty precipitation. Avalanche Energy has invented a novel solar thermal collector for heating residential domestic hot water. Solar thermal energy is often greeted with skepticism for its long payback and heavy, unattractive roof-mounted collectors.

For most homeowners the financial attractiveness of solar thermal energy is devastated by expensive modules, low efficiencies, and cheap natural gas. Even when the technology is desired, many homeowners struggle to qualify for loans to cover the upfront investment or are turned away because of inadequate roof orientation and structural support. However, market barriers are simply a precursor to innovation and perhaps Avalanche’s unique design can address these issues to create new opportunities in the solar thermal market.

Avalanche’s product, also known as the SunTracer, features two parabolic reflective dishes to optically concentrate solar collection on a single heat transfer point. The SunTracer system ties directly into the homeowner’s domestic hot water heater, so that a secondary heat transfer loop is not necessary. Having fewer heat transfer points reduces system losses and increases the net system efficiency. The module boasts a theoretical maximum efficiency of 81%. Not only is it more efficient than traditional flat plate rooftop collectors, but it can capture solar energy for a longer period of the day. The SunTracer leverages two servo motors and a global positioning system to rotate on two axes as its tracks the sun throughout the day.

Higher module efficiencies and longer periods of solar collection improve the customer’s annual energy savings and rate of return over that of conventional solar thermal technologies. Using a single transfer point with concentrating dishes reduces the water weight and rooftop footprint that would be required by a flat-plate collector for the same amount of savings. Solar tracking enables customers with poor rooftop orientations to take advantage of solar energy, and while approximately 50% of the population uses natural gas for water heating, the other 50% uses electricity, propane, or fuel oil, which offer much better paybacks. These units are small and not intended to completely offset fuel consumption, but rather supplement the water heater, improving the net water heater system efficiency. By providing smaller units, Avalanche can make them less expensive. Avalanche envisions the SunTracer to be a unitary system that can be purchased for as low as $2,000 before applicable incentives and tax credits.

For more information, visit their website: