SolarWall^® Photovoltaic / Solar Thermal (SolarWall PV/T^TM)

Adding SolarWall® to photovoltaics (PV) dramatically reduces ROI timeframe

SolarWall® PV/T^TM (photovoltaic + solar thermal) is a hybrid system which provides up to 4 times the total energy from the same surface area. The secondary benefit is to reduce the operating temperature of the PV modules and thereby improve electrical performance. The patented system provides both PV generated electricity and warm air for building ventilation or process heating.

Why SolarWall^® PV/T^TM?

PV modules are mounted slightly above the SolarWall® surface where air is drawn in and behind the modules. SolarWall® PV/T produces the following benefits:

• Increased electrical production by decreasing module temperature. Testing has verified that removing the heat energy with the SolarWall® collector improves the PV efficiency by up to 10%.  The cooling effect allows the PV panels to operate at their rated electrical output and also prevents damage caused to PV modules caused by overheating.
• The heat energy captured from the PV modules is used to displace the traditional heating fuel in the building.  The SolarWall® PV/T hybrid system can be sized to deliver an additional 200-300% more heat energy over a conventional PV system.
• The SolarWall® system replaces the typical racking system needed to mount PV.

Collectively, the increased energy production and low additional cost serves to accelerate the PV system return on investment.

*SolarWall® system output when combined with PV
Note: SolarWall® output without PV is 500-600 Watts/m²

Up to 300% more total energy for only 20% additional cost!

Additional benefits include:

• System addresses the majority of a building’s energy requirements (electricity and heat)
• Huge reduction in greenhouse gas emissions.  Displacing the heating load is typically a direct source reduction from CO₂ because the fuel being displaced is usually natural gas or heating oil.
• Hedges against both electricity and heating costs
• Maximizes usable roof space
• Engineered to meet site conditions

The Science behind the SolarWall^® PV/T^TM System

Top, SolarWall PV/T being installed at the John Molson School of Business at Concordia University
Bottom, Building integrated SolarWall PV/T on the completed building

Conserval Engineering originated the concept of combining PV with SolarWall, which is also available now in a modular rooftop system called SolarDuct PV/T. The goal with the SolarWall® PV/T system was to address some of the problems inherent with conventional photovoltaics, and to develop a solution that would further enhance PV as a viable renewable energy solution. Two problems that can make PV unattractive are the long payback periods and the low efficiencies.  By combining SolarWall with PV into one technology provides a solution to both of these problems.

Typical PV modules have a solar conversion efficiency up to 15%.  The remaining energy produced is heat, which is neither captured nor utilized.  This means that PV panels actually generate 2-4 times more heat energy than electricity. This heat increases the operating temperature of the PV modules, which actually decreases their overall performance – and sometimes very significantly. Overheating of a PV module decreases electrical power generation performance by 0.4-0.5% for every 1°C about its rated output temperature (which in most cases is 25°C).  This is why the concept of “PV cooling” has become so important.

The solar thermal SolarWall panels cool the PV modules and enable the "waste heat" to be removed and utilized for practical heating purposes.  By removing the excess heat generated by the PV modules, the electrical output is also increased.  Modules can commonly operate at temperatures over 50 degrees C above ambient temperature, resulting in a performance reduction of more than 25%.  By dissipating the heat from the module and lowering the operating temperature, significant gains can be made in system performance and the heat can be utilized for practical heating purposes.  As a result of these effects, the testing showed that the payback on a PV system that incorporates a solar heating component could be reduced by between one third and one half.

The performance of the SolarWall PV/T hybrid system was established through testing at the National Solar Test Facility, in conjunction with the International Energy Agency Task 35.  The results documented that adding the SolarWall thermal component to a PV array boosts the total solar efficiency to over 50%, compared with 10 to 15% efficiency for most PV modules alone. The heat from the PV panels, captured by the SolarWall perforated absorber, was documented to be three times more than the electrical energy generated from the PV modules. This means that by being able to uniformly capture and utilize the excess heat, it becomes possible to realize an energy output improvement in the range of 200-400%, depending on air flow and other design considerations.  The test data also showed that the temperature gain from the PV modules is between 6°C to 20°C or well within the typical range for a SolarWall® solar heating system.

More Information on SolarWall PV/T

Below are SolarWall PV/T leaflets that contain additional information on the SolarWall PV/Thermal and SolarDuct PV/Thermal (roof mounted) cogeneration products.  You can download the PDF (requires a PDF reader; such as Adobe Reader) or view it online using iPaper (which requires Flash).

• SolarWall PV/T and SolarDuct PV/T - Solar Air Heating and Electricity (PDF)
  View the iPaper version