Commercial Solar Electric PV Buildings In New Zealand

Issue 52, April/May 1997 EnergyWiseNews - By Cathy Sheehan & Simon Cope

Sun-powered buildings
Buildings equipped with solar cells as part of their roofing, cladding or glazing can use the electricity grid like a giant storage battery, selling the excess power they generate, and drawing it off when it's needed. Simon Cope outlines new developments.
The last two decades have brought significant changes to the design profession. In the wake of escalations in energy prices, shortages, embargoes and war, along with heightened concerns over pollution, environmental degradation and resource depletion, awareness of the environmental impact of design professionals' work has dramatically increased.

In the process, the shortcomings of yesterday's buildings have also become increasingly clear: inefficient electrical and climate conditioning systems squander great amounts of energy. Combustion of fossil fuels on-site and at power plants adds greenhouse gases, acid rain chemicals and other pollutants to the environment. Inside, many building materials, furnishings and finishes give off toxic by-products, contributing to indoor air pollution. Poorly designed lighting and ventilation systems can induce headaches and fatigue.

Environmentally responsive
Architects with vision have come to understand it is no longer the goal of good design to simply create a building that's aesthetically pleasing - buildings of the future must be environmentally responsive as well. They have responded by specifying increased levels of thermal insulation, healthier interiors and heat recovery ventilation systems. Significant advances have been made, and this progress is a very important step in the right direction.

However it is not enough. For the developed countries to continue to enjoy the comforts of the late twentieth century, and for the developing world to hope to ever attain them, sustainability must become the cornerstone of our design philosophy. Rather than merely using less non-renewable fuel and creating less pollution, we must design sustainable buildings that rely on renewable resources to produce some or all of their own energy and create no pollution.

One of the most promising renewable energy technologies is photovoltaic (PV) solar electric modules or cells. Photovoltaics are a truly elegant means of producing electricity on-site, directly from the sun, without concern for energy supply or environmental harm. These solid-state devices simply make electricity out of sunlight, silently with no maintenance, no pollution and no depletion of materials. Photovoltaics are versatile - the same technology that can pump water, grind grain and provide communications and village electrification in the developing world, can produce electricity for the buildings and distribution grids of industrialised countries.

Distributed power
By generating their own power while remaining connected to the electricity grid, buildings equipped with arrays of PV cells can use the grid like a giant storage battery. Buildings feed excess power to the grid during the day, helping the power companies to shave off the spikes in peak electrical demand. Then, when the sun goes down, these buildings draw electricity off the grid. It's a win-win situation: owners get paid for power they don't need, and power companies don't have to spend millions on new power plants to meet peak demand.

Building-integrated PVs hold the promise to provide distributed electricity all across our country. Tens of thousands of square kilometres of unused building surfaces are bathed in sunlight every day, all going to waste.

Interest in the building integration of PV, where the PV elements become an integral part of the building, often serving as the exterior weathering skin, is growing world-wide. PV specialists from some 15 countries are working within the International Energy Agency's Task 16 on a five-year effort to optimise these systems. Architects in Europe, Japan, the US and New Zealand are now beginning to explore innovative ways of incorporating solar electricity into their building designs.

World-wide, the first trend was for PV modules to be installed on top of existing roofs, supplying power to a battery bank in the basement of the building. Sophisticated electronic control equipment then converted this electricity into useable mains power for use by the building.

The next stage was to take these traditional, standard glass-fronted PV modules and make roof tile shapes out of them. What makes this different is that the PV modules are the roof. It was merely the second phase of a revolution. The biggest problem with these traditionally-made PVs has been the cost of manufacture, the glass on their front, the inability to cope with heat (loss of output), and the shading problems that occur.

Canon Inc, and the Pilkington group, came up with the answers to these problems. Both end products are completely different from each other in technology and usage.

Solar sandwich
Pilkington Solar International (Pilksolar) a subsidiary of Pilkington group, one of the world's largest glass manufacturers, was set up to concentrate on the company's solar-related activities.

Pilksolar has developed a technique of laminating conventional raw PV cells between two layers of glass. These facade elements can be produced in sizes up to 2.1 x 3.2 metres. The transmissivity can be adjusted to the customer's needs, using different arrangements of the solar cells. Depending on the application, the energy facade elements can be built as double glazing units with high thermal insulation, sound or burglary protection. The frameless Optisol® facade elements can be used like regular glass panes with almost all profile frame systems.

Optisol® energy facade elements are integrated into a roof skylight at an angle of 25 degrees, facing south (in the northern hemisphere). The dense polycrystalline cells render interior sunshade protection superfluous.

Dynamic examples of the application of PV elements in areas like parapets, glazed stairwells, entrances, attics, skylights in hallways, glass roofing and all kinds of inclined roofs have all been successfully achieved by Pilkington Solar.

Roofing materials
Highly efficient amorphous silicon solar cell technology is the key to Canon's expected domination of world PV production this year. The company's move to solar cell manufacture, which follows 19 years of research, was boosted in 1993 when the Japanese government introduced a subsidy scheme to promote the commercial installation of PV technology. The technology used by Canon is claimed to be the biggest breakthrough in recent solar cell research. Its manufacturing costs are 50% lower than conventional manufacture, and the Canon cells are more efficient energy generators.

Canon has developed a large range of products with this technology:

  * standard PV modules suitable for single module use, such as recreational vehicles, holiday homes, houses, and commercial buildings where the existing roof structure is intact;
  * flexible (floppy) modules for marine and camping use;
  * UniKits, an easy-to-install, all-in-one kit which is a solar lighting and power system for remote cottages, garden sheds, garages etc;
  * roof-integrated solar modules.

Canon roof-integrated solar modules are designed to look and function as attractive roofing components for the homes and buildings in which they are installed. They are thin, flexible and light, adding no unnecessary weight or bulk to the roof structure. They are also laminated with advanced polymers, making them highly water-resistant, durable and resilient to high temperatures, and are manufactured with uniform dimensions for easy incorporation into construction plans. For these reasons, the roof-integrated solar modules cost less to install than other products and save users the double expense of installing roofing and solar modules separately.

Solar Energy House C/- Simon & Kristina Cope | 19 Manapau Street, Meadowbank, Auckland 1072 | New Zealand | Contact us now to arrange your tour