Solar energy takes advantage of the sun’s rays to generate heat or electricity. It is an infinitely renewable resource and unique for its ability to generate energy in a quiet, clean, and consistent manner.
While both types of solar systems capture energy from the sun, solar photovoltaic systems use photovoltaic panels to produce electricity. Solar hot water, or thermal, systems capture sunlight to heat water for domestic use, to heat a swimming pool, or for a radiant heating system.
Photovoltaic energy enables generation of electricity directly from sunlight. The solar cells used for this process are semiconductors, usually made from silicon. When sunlight falls on a solar cell, electrons in the cell are set into motion, generating an electric current. A closed circuit connected to an end user’s home electrical wiring or to a power grid is essential.
Physically, solar cells can only generate direct current. The generated electricity can be used to directly charge storage batteries or utilized by a DC power consumer. Known as off-grid solar power systems, they are deployed in areas where access to a public grid is not available.
Grid-connected systems require inverters to convert the DC into AC power. Solar power is fed directly into the power grid, the amount measured by an installed meter and subsequently remunerated.
Using solar power to heat your water is one of the most practical and cost effective ways to harness energy from the sun. Solar thermal systems absorb the sun's heat and use it to heat your residence's own hot water needs. In general, the solar thermal system will easily heat water to 60ºC or higher matching the range of its traditional hot water tank counterpart. Effective systems can collect up to 70 percent of the sun's energy that reaches them and transfer it to you.
In general there are two types of active water heating systems: direct and indirect.
Direct Solar Water Heating
As implied, direct systems capture the sun's heat in collectors to directly heat a household's water supply. The system consists of collector pipes filled with water that are linked to an insulated storage tank usually located inside a home. As the sun heats the water inside the pipes, the water flows into the storage tank. Although direct systems are more efficient that indirect ones, they require more maintenance to keep the pipes clear of mineral deposits. Direct solar thermal systems also work best in warmer climates where the system is less prone to freezing.
Indirect Solar Water Heating
Indirect systems do not heat the water directly rather they use fluid with a low-freezing point to absorb radiant energy from the sun. Also termed closed-loop systems, an indirect solar water heating system absorbs the sun's rays into heat pipes evacuated of air which in turn heats up the pipe's thin copper laminate located on the back of each pipe. The collection array consists of multiple heating pipes that are mounted and tilted to maximize solar collection.
Often glycol (an ingredient in antifreeze) runs through adjacent pipes within the array and heats up via contact with the copper laminate. As the temperature in the pipes rise, the heat activates a pump that circulates the glycol fluid through a heat exchange coil in the water tank. That coil, in turn, transfers its heat to the water tank and voila, hot water is produced.
Solar pool heating systems work on a similar principle to a direct system solar hot water heater. However, because the water can heat up too much in a solar thermal system, the collector's glazing is often removed. Using non-glazed pipes or a heating system that resembles a flat black mat prevents the pool water from becoming super-heated as well as reduces costs to the overall system.
Absolutely! Radiant heating applies solar thermal technology. Transferring solar energy through pipes into an under floor radiant heating system is a wonderful way to stay warm. Radiant floor systems are typically 40 percent more efficient than their forced air counterpart and can be zoned to match thermal comfort to each room.
Solar panels are flat panels of photovoltaic arrays mounted on a roof or a pole to capture the sun’s rays. Building integrated photovoltaic materials are PV arrays that are integrated into the building material itself, primarily windows, roof tiles, or walls. Solar panels work well for retrofits or remodels while BIPV are appropriate for new construction or a major renovation.
A 2kW solar electric system will cost approximately US$ 6,000. That total includes the cost for all components – solar panels, panel mounts, and inverter – and labor associated with installation. It does not however, reflect all the avoided costs, such as the tax breaks, FiT payments or the credits received through net metering.
Solar photovoltaic panels require little maintenance – no need to wash or dust. It is, however, important to place panels where they will remain clear of shade and debris. Thus you will have to wipe them off if too much snow or leaves fall on them.
Solar hot water collection arrays don’t need much attention either. It does help to periodically use a window wash brush, biodegradable soap, and water to clean the tubes.
Planning, configuring, and doing any custom ordering for your solar energy system can take up to a few weeks. However, the installation process itself can typically be completed in only a few days, in many cases even less!
Although solar energy systems work in parallel with conventional residential electrical and plumbing systems, there are tricky things in the process well suited to seeking out professionals who specialize in solar power installation. Solar installation professionals can help you determine the type and size of system most suited for your needs.
Solar professional installers can take the guess work out of installing a solar power system. Whether you are considering solar photovoltaic, wind turbine, solar hot water, or solar heat for your pool, a solar expert can help you determine the type and size of system that will work best and guide you through the process.
As with any major purchase, it’s helpful to compare costs and information. Seeking information from multiple professionals can provide constructive advice, set realistic expectations, and help you fine-tune the design that will work best for your application.
In bright sunlight, a square meter of a conventional photovoltaic panel will yield 160 watts of power. That’s a helpful rule of thumb for calculating a rough estimate of how much area you might need. For example, a 1000 watt system may need 16 – 20 square meters of area, depending on the type of PV module used, the orientation and obstacles on the roof.
Unfortunately shading a photovoltaic system dramatically decreases its output. Just shading the bottom row of wafers alone amounts to an 80% reduction in efficiency. So above all, don’t shade your array!
Like other types of solar energy systems, solar hot water heating systems work best on south-facing walls with full sun exposure. Because of the collector tubes' type of construction, the outside elements have less effect on its performance compared to a photovoltaic collection system; a bit of shade on the thermal array will have a less noticeable impact.
The location of your home and the local climate will play into where you place and how you install your solar electric or solar hot water system. Wind speeds, heavy snow loads, and salt water can all affect a solar array. Understanding how those inputs effect performance will determine the types of mounts or how the arrays are angled. A solar expert in your area is likely quite knowledgeable about your local conditions and can help you design that works well for you.
Most wind turbines have three blades which face into the wind; the wind turns the blades round, this spins the shaft, which connects to a generator. A generator produces electrical energy from mechanical energy.
The actual wind speed at your site will be influenced by the local topography and any nearby obstructions such as trees or other buildings. Wind movement around buildings themselves is very fickle, so take expert advice. A site with an average wind speed of 4-5 meters per second is generally sufficient enough to make installing a small wind turbine worthwhile.
Tower height varies according to wind turbine models, but generally ranges from 6 to 24 meters. In general, the higher the tower, the higher the average wind speed that the turbine will experience and the smoother the wind. The rotor diameter of small wind turbines ranges from 2.0 to 7 meters depending on the type of a model.
Ideally, stand-alone turbines should be sited as far away as possible from buildings or trees, which may block the wind and cause turbulence. As a guide, the wind turbine should be about twice the height of obstructions in the immediate front of it (for at least the prevailing wind direction). In general, the turbine should be above the height of nearby obstructions that are within a distance of 10 to 20 meters of the tower heights.
Rooftop-mounting turbines is not something generally recommended. It is fairly difficult finding a place on a roof that is strong enough to withstand the forces and has a good wind. Local turbulent airflow around the building, which causes reduction in generated output and could damage the turbine, must be considered as well. In general, the less turbulent and varying the wind, the better the wind power generation.
The maintenance required for small wind turbines is likely to be minimal. Wind turbines are designed for over 20 years life time. Usually bearings are greased for life and sealed so you don't have to grease them annually. But an annual check is likely to be required and can be performed by yourself or your solar expert.
Small wind turbines have been designed to be very quiet, for instance by having direct drive systems to avoid gear box noise and to increase efficiency. In general, the wind itself makes more noise than a wind turbine. It is most unlikely that any noise from small wind turbines will be heard at more than 30 m.
Small wind turbines are unlikely to have any detrimental effects on aviation and associated radar or navigation systems. In general, turbines with small diameters are unlikely to have effects on television and radio reception. If this occurs it is likely to be highly localized and technically easy to overcome.
Experience and careful monitoring by independent experts shows that birds are unlikely to be damaged by the moving blades of wind turbines.
In the case there is a Renewable energy support scheme in your country with a fixed price payment for a specific period, the solar electricity is normally all fed into the grid, as the remuneration is usually higher than the price paid for using electricity from the grid. In this case, the energy received from the grid and that which is fed into it are registered and calculated separately using in most of the cases two meters.
Net metering is a service to an electric consumer under which electric energy generated by that electric consumer from an eligible on-site generating facility and delivered to the local distribution facilities may be used to offset electric energy provided by the electric utility to the electric consumer during the applicable billing period.
Feed-in-tariff is a policy mechanism designed to accelerate investment in renewable energy technologies. It achieves this by offering long-term contracts to renewable energy producers, typically based on the cost of generation of each technology. Rather than pay an equal amount for energy, however generated, technologies such as wind power, for instance, are awarded a lower per-kWh price, while technologies such as solar PV are offered a higher price, reflecting costs that are higher at the moment.
Off-grid photovoltaic systems function independently of a grid power supply. The solar electricity produced during the day is stored in a battery, and thus is also available at night and in periods of bad weather. A charge controller monitors the charge status of the battery and provides protection against overcharging and complete discharging, which will ruin the batteries.
Smaller systems working with direct current are often used in the hobby and leisure sector. They provide power to summerhouses, holiday homes, motor homes and boats. Typical applications in the commercial sector are telecommunications, measuring and controlling systems, and cathodic corrosion protection. For higher electricity demands, a system with an inverter is recommended. These systems provide alternating current, just like power from the grid, and are suitable for supplying power to residential houses, schools, and clinics. Given the correct sizing, power supply systems for entire villages may be produced.
Solar water pumps function without batteries. The solar generator powers centrifugal or membrane pumps directly. A water tank takes over the role of the battery: instead of electrical energy, water is stored and may be used at any time.
Specific to developing countries is the lack of infrastructure for a stable electricity supply. Sparsely populated rural regions are particularly affected by this. Not only is the quality of life in private households impaired in villages without electricity, but there is also no way of developing an economic infrastructure.
This is where the hybrid solar systems offer a solution. These systems are not dependent on conventional fuels such as oil and gas, they are made up of a photovoltaic system, a small wind turbine and an electricity generator which can run on vegetable oil or other alternatives. During peak load times or when, due to a lack of sunlight or wind, the solar system and wind turbine can no longer supply the required output, the generator comes into operation.