Suddenly solar Bloggers are discussing BIPV. There is a growing agreement that it is a coming reality for buildings on both residential and commercial roofs. We are not surprised. We are literally the pioneers in North America for BIPV thanks to getting a head start with our Swiss origins. We began our first production in Virginia 1997.
Before speaking about solar though, there are smarter ways to build homes than are normal in USA. Europe is famous for longer lived buildings and part of the credit goes to not small how roof are built and covered there. Our company was originally Swiss. We have borrowed wholesale the Swiss approach to building roofs. Instead of the laying a membrane on a plywood deck, we us a lattice or counter batten on top of a membrane. We then attach the slates to the counter-batten. Please see
You will notice that the slates overlap generously. If it were possible for wind driven rain to penetrated the overlap it would gutter down between the vertical support members without being trapped. Each day the roof warms and any moisture the enemy of all roofs is heated and expelled from the plenum of free air. This plenum air further acts as an insulator from the attic. Actual test confirm a 14 degree F cooler attic under this type of roof construction. The building saves on air conditioning costs even without solar!
Continuing, still without discussing solar electric advantages of this mode of construction. That previously mentioned hot air in the plenum is valuable to home or business owner or dweller. Solar thermal is not as sexy as solar electric but it is dependable and cheap! Our company uses a patented system called BITERS short for Building Integrated Thermal Energy System. It does two important tasks. It cools the Sunslates or TallSlates modules making them more efficient. It carries the thermal energy to a location that it can be more productive e.g., a swimming pool or domestic hot water or to a geothermal underground bank to be extracted in winter months. Depending on location, the thermal energy is 1.5 to 4.0 times greater than the solar electric!
Combining the two energy sources on one building is incredible! Also the thermal collection is invisible to the eye but very helpful on the monthly utility bills.
Many are surprised that hot weather can work against good solar electric production, but it’s true. That is why NASA uses solar in deep cold space so effectively. Cooling a solar roofing is critical to productivity. That is a key reason why we invented BITERS to cool our Sunslates as you can see in this image of the construction for Future House USA in Beijing for the 2008 Summer Olympics. The BITERS system is a series of metal stripes with a circulating fluid to scavenge thermal from the underside of the Sunslates or TallSlates. Like all of our designs it is two for one, improving electric production and rerouting the thermal to a productive purpose.
Most commodity solar modules are rectangular and increasingly large. They are challenging to place on roofs with multiple angles, penetrations like sewer stacks, and dormer bumpouts. By keeping our exposures of Sunslates to 1.3 square feet, 2.0 square feet and 4.0 square feet for TallSlates we can fit the architecture of the roof beautifully.
We supply our contractors with two size of Sunslates. the smaller one The Sunslates5 is ideal for more “cut up” or angled roof plans, as pictured above. The Sunslates6 is 2.0 exposure and works ideally for large format roofs as below.
Finally the TallSlates that are designed to fit into Greenstone slates system. It is larger at 4.0 exposure allows for more rapids and economical installation and uses the same high performance cells as the two Sunslates systems.
All of our solar roofing systems are designed to optionally accommodate the BITERS thermal system. All will produce, depending on solar resource, 1350 Watts per roofing square(100 square feet)
These few examples of the benefits of choosing true building integrated solar, electric and thermal just the beginning. The aesthetics speak for themselves. They have been Dade County tested for high winds. Some years ago, the largest roofer in California Old Country Roofing, told us that they were so impressed. They had never had a roof leak. That is true for our solar roofs across the USA, Canada, Europe and Asia. Snow in cold country cannot get trapped on or under them. They are walkable for cleaning but very slick so only with safety harness.
Roofers understand the importance of keeping water out of buildings. They also are very aware of aesthetics. We train our roofing contractors to handle the electrical connections on the roof including continuity testing so that they can hand dependable information to the solar contractors in the attic or where ever the home runs are being connected. That keeps the costs down and the quality high.