Here’s a Tiny Solar-Thermal System for Your Tiny House

Tiny houses don’t have much room on their tiny roofs, and that’s a problem when it comes to finding space for solar panels, let alone a combined solar power system that can generate both electricity and heat. However, help is on the way in the form of a new compact photovoltaic thermal energy system under development at Michigan Technological University, and it could help make off-grid solar power more cost-effective for larger buildings, too.

Rooftop Real Estate and Solar Power

The installed cost of solar power would be substantially lower with an integrated system that maximizes all of the available solar potential in a relatively small space.

The good news, according to MTU, is that commercially available solar systems are already highly cost-efficient at collecting solar energy for heat and hot water.

The bad news is, thermal systems are not as popular as they could be, because all you get is the heat and hot water. For electricity you need photovoltaic panels, and since conventional solar panels can easily take up all of the available roof space, that leaves the thermal system out in the cold.

A New Silicon Solution for PVT Systems

Lead researcher Joshua Pearce focused on thin-film silicon technology, which is far cheaper than conventional solar cells based on crystalline silicon. For rooftop applications, it also has a weight advantage.

However, thin-film technology faces a major obstacle. Its efficiency can degrade significantly after prolonged exposure to light, an effect called the Staebler-Wronski effect.

Pearce’s solution, developed in collaboration with the company ThinSilicon and Queen’s University in Canada, basically involved creating thicker thin-film cells that can be applied directly to a solar thermal energy collector.

The thicker cells essentially overcame the Staebler-Wronski effect, and the research team also found that they could even boost their electrical efficiency by about 10 percent, by “baking” them in near-boiling temperatures once a day (a process called spike annealing).

Distributed Solar Power and SunShot

Aside from helping to spread the solar love around to more building owners, a high-efficiency, low-cost PVT system could have important implications for the Obama Administration’s national energy policy.

One element of the policy is the transition to smart grid technologies that rely more on distributed energy, including rooftop installations. Along with supporting more clean energy and energy efficiency, the distributed energy model will help to reduce the threat of widespread power outages in an era of increasingly erratic weather.

Another key element is the SunShot Initiative, named after the iconic 1960’s era Moon Shot program that rapidly vaulted the U.S. from an also-ran to the winner of the race to the moon.

The aim of SunShot is to bring the cost of solar power down to parity with fossil fuels, while propelling the U.S. back into the leadership position it once held in the global solar energy market.

Part of the SunShot effort relies on increasing the efficiency of solar cells, but equally important is its focus on simply lowering the cost of installing solar systems, and that’s where Pearce’s integrated PVT system could offer the most significant savings.

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