If you’ve ever wanted to see the potential of solar thermal energy, watch this video below. Or better yet, go to Okotoks, Alberta, and see The Drake Landing Solar Community (DLSC), a unique solar water heating AND solar space heating housing development in Canada.
According to the DLSC website, this solar development of 52 homes is the first of its kind in North America. What’s so solar “gee-whiz’ about the development is that every home is heated by a huge central solar heating system that stores solar thermal heat underground during the summer months and distributes the energy to each home for space heating needs during winter months.
(Click to enlarge)
The solar storage technology is called Borehole Thermal Energy Storage (BTES). On first glance, the concept seems similar to a geothermal heating system, but it’s not. Of course, the main difference is that the thermal power source is coming from the sun, not from the earth’s crust.
According to the developers, this BTES system heats 90% of each home’s space heating requirements. And yes, that includes Canadian winters. The remaining 10% is backed by a natural gas heater. In addition to solar space heating, each home has its own flat plate solar water heating system on top of the garage. As for the homeowner’s energy costs, it’s structured as a flat monthly fee that is less expensive than gas or oil heating.
(click to enlarge)
Other solar details:
- The Development’s system consists of 800 flat-plate glazed collectors.
- 50% propylene glycol antifreeze
- Mounted on four rows of garages, with two rows of collectors per garage
- Azimuth – south; tilt – 45°
- All 52 houses are serviced by direct-buried, pre-insulated piping.
- Short-term thermal storage (STTS) tanks are central hub for heat movement between collectors, district loop (DL)/houses, and (BTES)
- The District Loop moves heat from the STTS to the houses
- BTES is connected to the STTS through a heat exchanger, all located within the Energy Center, a separate building. (See video).
- There are 4 individual home-run loops off a manifold in the Energy Center.
- Water temperature is modulated based on outdoor temperature.
- Flow is modulated based on the number of houses calling.
Borehole Thermal Energy Storage (BTES) Details
Above ground, it looks like a wide open park. But below ground….
- There are 144 – 150mm dia x 35m deep boreholes spaced 2.25m on center.
- Single 25mm PEX U-tube with 40mm grout tube.
- High solids grout – 9% Blast Furnace Cement, 9% Portland cement, 32% fine silica sand, 50% water
- 24 strings of 6 boreholes in series.
- Divided into four circuits and distributed through four quadrants so that the loss of any single string or circuit has minimal impact on the heat capacity on the entire system
- All circuits and strings start from center of the BTES and move toward the outside to maximize stratification.
Here’s an abbreviated promotional video from DLSC. The section shows how the BTES works:
It’s very exciting to see innovative solar thermal developments like this. We sincerely wish the developers of The Drake Landing Solar Community great success.
Contact Free Hot Water about designing solar hot water or space heating system for your green housing development.
