What Type of Solar Energy System is Right For Your Home?
Solar power systems generate electricity from sunlight. They can be grid-tied or hybrid.
Solar energy has many benefits over other sources of electricity. However, it has certain environmental impacts.
Solar technology has a long history. It all started in 1839 when French physicist Edmond Becquerel discovered the photovoltaic effect.
Solar Photovoltaic (PV)
A PV system uses solar panels to convert sunlight directly into electricity. Sunlight is made up of different colours of light, each with a specific energy level (also known as wavelengths). Some of this spectrum is reflected and some cannot be converted to electricity (for example infrared SOLAR ENERGY SYSTEM and ultraviolet). Solar photovoltaic cells are designed to capture the sunlight with the most amount of energy and generate the highest voltage.
The most common semiconductor material used in PV cells is crystalline silicon. The crystal lattice of silicon atoms gives the cell an organised structure that helps convert sunlight into electricity efficiently. Thin-film solar technologies use a range of other materials, such as cadmium telluride and copper indium gallium diselenide, which offer a lower cost than traditional crystalline silicon cells.
A solar PV system is usually connected to a battery, which stores excess power and can be drawn upon when demand is high. In stand-alone systems, the battery is located as close to the modules as possible, which minimises power losses. In grid-connected systems, an electronic device called a maximum power point tracker can optimise the DC-AC voltage conversion.
Many Australian states and territories offer incentives, such as interest-free loans or higher feed-in tariffs, to improve the financial return on a PV system. Choice recommends working with accredited installers and retailers when installing a new PV system.
Solar Thermal (CSP)
Concentrated solar power (CSP) systems focus sunlight through a series of mirrors, concentrating it to achieve high temperatures. This heat can then be used to drive a traditional thermal power plant or engine for electricity generation. CSP plants can also be coupled to thermal energy storage to improve dispatchability during cloudy or nighttime hours.
The primary CSP technologies are parabolic trough and solar power tower plants. While both systems have been proven at commercial scale, the CSP industry is currently focused on trough technology due to its low capital cost and efficiency compared to tower. Crescent Dunes, a 550 MW CSP project in the Mojave Desert, is a good example of trough technology.
Large CSP projects require a large amount of land. For example, a 100 MW plant will need five to ten acres per MW of capacity. CSP plants also need to be located in areas with high irradiance, as they use large mirrors to concentrate sunlight on a receiver to generate heat. The NREL has a tool to help determine the solar potential of a site.
Energy storage is an integral part of CSP, as it enables the system to provide flexible, dispatchable power. Current commercial projects use liquid molten salt as the storage medium, although new options for storage are being investigated including gases like air and liquid metals and solids like ceramics.
Solar Water Heating
Solar Water Heating (SWH) is a very efficient way to use the sun to heat your home’s water. This reduces your utility bills and also helps to lower carbon emissions. In many parts of the country, SWH can even be used to offset your electricity or gas usage.
The basic principle is that sunlight passes through a collector’s glass covering and strikes absorber plates within the collector. These plates are designed to capture the solar energy and convert it into thermal energy. The heat is then transferred to a storage tank or to the home’s water supply via a heat exchanger. Insulation materials are also crucial, reducing heat loss and ensuring that the heat is retained in the system.
There are two main types of solar water heating systems: passive and active. Passive systems are very simple, and work by positioning a hot water tank directly over or above the collector. As the tanks’ water gets warmer, it naturally rises into the collector. Active systems use a pump station and system controller that monitors temperature data to determine when the collector is hotter than the tank and to start the pump accordingly.
Both types of systems require regular inspection and maintenance to ensure optimal performance. Unless you are comfortable working on ladders, walking on roofs or performing soldering or hot work, it is important to hire a qualified technician for inspections and maintenance.
Solar Hot Water
Solar hot water (SWH) systems use the sun’s energy to heat your home’s water, cutting heating costs. They have been in use for centuries, but today’s technological advances make them suitable for virtually any climate.
The key components of SWH systems include solar collectors, a storage tank, a heat transfer fluid, a backup water heater, pipes and controls. A pump station or system controller solar water pump for home uses temperature data to manage the system, ensuring maximum performance. The heat transfer fluid is either potable water or a mixture of potable water and antifreeze, depending on the type of system. The antifreeze allows the system to operate in regions with freezing temperatures.
A solar storage tank is sized to match peak household hot water demand and the SWH’s production capabilities. It also contains a pressure relief valve and air vents at high points in the piping to prevent overheating. Indirect circulation systems are best for climates with frequent freezing conditions, while direct systems can be used in areas that don’t experience freezing weather.
SWH systems are relatively simple and inexpensive to maintain. O&M costs are generally less than 1% of the initial system cost, making them a smart investment for homeowners and businesses. The DOE’s Solar Water Heating website features a list of system types and a wealth of tips on selecting and maintaining a system.