The first cars to harness solar power were developed in the 1970s. Despite 40 years in the making, today they remain "concept cars" outside the mainstream market. While all models use photovoltaic cells, the most successful in terms of speed and reliability use PVCs to charge a separate battery, which is then inserted into the car. The biggest hurdle the solar automobile industry faces is the astronomical cost of building and purchasing solar-powered cars. Given that the top speed of even the most expensive solar vehicle is only around 60 mph, a price tag in the hundreds of thousands dollars is well beyond most consumers. However, this does not stop schools, corporations and amateur teams from taking part in solar car competitions. Since the early 1980s, annual races have been held all over the world, the most famous courses being the World Solar Challenge in Australia and the North American Solar Challenge, which runs from Texas to Calgary, Canada.
Solar heating is usually powered by photovoltaic cells on the roof of the home, ideally south facing at a 20- to 50-degree angle. There are two forms of solar heating, the more common using photovoltaic energy to heat water, which can then be used for radiated heat and swimming pools. In Scandinavia, passive solar energy is used to blow hot dry air into the home, both warming and dehumidifying. The limited energy that is produced through photovoltaic cells and their reliance on strong sunshine means that solar heating will not meet the demands of the average household in winter, when heating is required more urgently. While the efficiency of solar power can lead to significant savings in the long term, the cost of a specialist to install the cells, as well as the price of the technology itself, is a significant deterrent to most homeowners.
Outdoor solar powered lights have enjoyed much success in recent years as a cheaper, safer and easier-to-install alternative to line-powered systems. Solar powered lights utilize photovoltaic cells to capture solar energy, which is then diverted to a rechargeable battery. The quality of light produced is significantly poorer than that of normal electric lighting, meaning solar lighting tends to be used for decoration. More powerful spot lamps do exist but the energy requirements mean that both the battery and the photovoltaic cell have to be externally attached to the light via a cord, making them less aesthetically appealing.