New solar technology with curved panels is able to capture twice as much energy per area unit compared to conventional, flat models, raising the efficiency bar for high temperature solar thermal plants.
Rectangular, curved solar panels glitter in the sun. Lined up along side each other, they form a prototype construction with a distinct appearance, standing 3.5 meters high and 24 meters wide, located beside a straw-fired heating plant (Sabro Varmeværk) west of Aarhus, Denmark.
The new technology sets out to demonstrate and support the development of renewable energy technologies for district heating. Developed by Danish company Alpha-E and currently being tested in collaboration with the Municipality of Aarhus, the value propositions of the new solar technology include a very short construction phase, the ability to shift the panels according to the rays of the sun and using aluminium as construction material instead of glass:
“It requires a container, a fork lift truck and a little cement in the ground, then it’s pretty much done. Avoiding fragile materials such as glass, which easily shatters and requires special transportation, reduces costs. Our panels are also flexibly constructed, which means they can tolerate strong winds up to 35 m/s without breaking”, explains one of the co-founders behind Alpha-E, Kim Nichum.
Shifting with the sun
The solar panels shift with the sun, enabling greater efficiency, especially in colder climates such as the Danish during autumn and spring, where conventional solar systems are unable to supply demand because of the weak sun.
The curved panels concentrate the sunrays to a focal point on an absorbing tube with 99.6% accuracy. In addition the panels have reflection value between 90-97%, depending on whether the aluminium solar panels are treated or covered by, for instance a layer of film.
The curved design of the panels are inspired by satellite dishes, which are able to catch the sunrays and concentrate them to a 24 meter long tube centred in the middle of the construction, where the tube acts as a focal point.
Alpha-E aims for a target price of EUR 335 per square meter. The calculation for cents per kilowatt will be disclosed after the full calculation for the entire year in testing at the heat plant.
Higher temperatures
The technology also distinguishes itself in the area of heating. A standard solar collector can heat up water for a district heating plant up to 90-95 degrees Celsius, whereas the new technology in its smallest version, which matches the prototype, can reach temperatures of 250 degrees Celsius. The largest version, with solar collectors reaching 8 meters high and 24 meters wide, can reach temperatures exceeding 400 degrees Celsius.
“The largest facilities (…) are primarily used for big industry or energy farms, which for instance produce electricity. The smaller facilities are suitable for district heating plants or other industries, where the temperature needed ranges from 90 – 250 degrees Celsius,” explains the co-founder.
The Danish enterprise is also looking at alternative options for their technology, because Alpha-E wishes to seize opportunities internationally. Their technology can be relevant for associated areas such as cooling or desalination of fresh water, due to its higher efficiency.
