Solar Technology Options
There are many renewable solar options available. Click on one of the technologies below to learn more about it.
Photovoltaic
Panels
Evacuated
Tube Collectors
Flat Plate
Collectors
Photovoltaic
Thermal Hybrid Collectors
Photovoltaic Panels
Overview
Photovoltaic panels, also known as solar panels, collect energy from the sun and convert it into electricity. Domestic photovoltaic panels generate electricity to power household appliances or produce heat. Given that the sun is a renewable energy source, the electricity produced by photovoltaic panels is clean and carbon free. The only emissions associated with solar panels are the emissions generated during manufacturing and transportation of the panels Photovoltaic panels are becoming an increasingly popular heating technology among homeowners, especially in remote areas where there are little alternatives for other sources of electricity.
What is a Photovoltaic Panel?
Solar panels are made up of small photovoltaic cells that are connected, hence the name PV panels. Each panel consists of many cells. The photovoltaic cells are made from a semiconducting material, most commonly silicon.
When the sun shines on the silicon photovoltaic cells, an electric field is created, and hence electricity is produced. The sun's rays do not need to shine directly on the cells. However, the more direct the sunlight is, the more electricity is produced.
Types of Photovoltaic Panels
There are three common types of domestic PV panels:
- Monocrystalline PV Panels: This type of panel is made from a single piece of silicon. Therefore, it is most efficient, but also most expensive out of the three options.
- Polycrystalline PV Panels: This type of panel is made out of multiple silicon pieces which are melted together. This PV panel is less efficient than the monocrystalline panels, but are also more affordable.
- Thin-film PV Panels: This is the cheapest and least efficient type of solar panel; however, it is ideal for applications where great flexibility is required.
The most popular photovoltaic panel system is the grid-connected system. This allows electricity to be drawn from the national grid at times when the PV panels are inactive, such as at night. The alternative to a grid-connected system is a stand-alone system. This system uses solar batteries in order to store electricity produced throughout the day so it can be used later.
Advantages
- Low Operational Costs: As photovoltaic panels use solar energy to produce electricity, their operational cost is essentially zero. The only operational costs are associated with the price of electricity in instances where electricity is drawn from the grid.
- Environmentally Friendly: Photovoltaic panels account for no CO2 emissions, as they provide clean, green energy.
- Renewable Energy: Solar energy is is an abundant resource and does not have a limited supply.
- Low Maintenance Cost: Photovoltaic panels have lower maintenance costs compared with other renewable energy systems.
- Silent: PV panels have no moving parts, and therefore are totally silent.
- Support: PV panels can be easily integrated with other heating technologies in order to meet the household's demands.
Disadvantages
- Reduced Reliability: As electricity production from PV panels depends on the weather, this might pose a problem during cloudy or rainy periods.
- High Capital Costs: PV panels are one of the most expensive heating technologies in terms of upfront cost, especially if combined with storage batteries.
- Low Efficiency: PV panels have a low efficiency compared with other renewable heating technologies.
- Fragile: PV panels can be easily damaged by external factors, such as heavy hail for example.
Evacuated Tube Solar Thermal Collector
Overview
While photovoltaic panels use the sun’s energy to produce electricity, evacuated tube systems harness the sun’s energy by converting the radiation into heat, which is later used to heat up the water in the home’s central heating system. Given that the sun’s energy is a renewable source, the heat generated by an evacuated tube system is clean and carbon free. Evacuated tubes have already been used across the world as a water heating technology.
What is an Evacuated Tube Solar Thermal Collector?
An evacuated tube collector system consists of rows of parallel, transparent glass tubes supported on a frame. Each individual tube consists of two components: a thick outer glass tube, and a thin inner glass tube. Both tubes are made from extremely strong glass. The inner glass tube, also called ‘thermos-flask tube’ is coated with a substance that absorbs solar energy while preventing heat loss.
The air between the tubes is evacuated, forming a vacuum between the two glass layers. This plays an important role in the performance of evacuated tubes. There is a metal heat pipe attached to an absorber plate inside each inner glass tube. The role of the absorber plate is to transfer heat from the tube to the liquid flowing through the metal heat pipe. The heated liquid then travels to a copper heat exchanger, where cold water flows in and hot water flows out. The hot water is then stored in a very well-insulated hot water tank, so that it can be used throughout the night or even the next day.
One of the most important aspects of evacuated tube collectors is the installation angle, as performance and efficiency depends on this factor. The installation angle largely depends on the latitude of the location. Similar to photovoltaic panels, evacuated tube collectors can be installed on the roof of a property. In some cases, evacuated tube systems can be mounted independently outside the house, for example in the garden.
Advantages
- High Efficiency: The evacuated tube solar collector system is the most efficient type of solar hot water system.
- Low Operational Costs: As evacuated tube collectors use solar energy to produce hot water, their operational cost is essentially zero.
- Environmentally Friendly: Evacuated tube collectors account for no CO2 emissions, as they provide clean, green energy.
- Renewable Energy: Solar energy is supplied by nature and does not have a limited supply.
- Low Maintenance Cost: Evacuated tube collectors have lower maintenance costs compared with other renewable energy systems, as tubes can be replaced individually.
- Support: Evacuated tube collectors can be easily integrated with other heating technologies (except combi-boilers) to meet the household demand.
- Cold Weather Performance: Evacuated tube collectors can perform well and heat water to high temperatures even in sub-zero environments.
- Incentives: Evacuated tube collectors are eligible for the Renewable Heat Incentive, meaning homeowners can receive part of their investment back.
Disadvantages
- High Capital Costs: Evacuated tubes systems are the most expensive solar hot water technology.
- Need for a Backup Heater: Although evacuated tube collectors can produce hot water during wither months, a backup heater might be needed on some occasions in order to meet household demands.
- Incompatible with Combi-Boilers: Solar hot water systems are not compatible with combi-boilers.
- Fragile: Evacuated tube collectors can be easily damaged by external factors, such as heavy hail for example.
Flat Plate Solar Thermal Collector
Overview
Similar to evacuated tube collectors, flat plate collectors harness the sun’s energy by converting the radiation into heat, which is later used to heat up the water in the home’s central heating system. Given that the sun’s energy is a renewable source, the heat generated by flat plate collector systems is clean and carbon free. Flat Plate Collectors have already been used across the world as a water heating technology.
What is a Flat Plate Solar Thermal Collector?
The main component of a flat plate collector system is the heat absorbing plate, usually made from copper or aluminium, as these two materials are good heat conductors. The heat absorbing plate is covered with a black coating so that it can absorb as much solar radiation as possible. In order to absorb solar energy, the flat plate needs to be installed with the heat absorbing plate facing towards the sun.
Parallel copper pipes are soldered lengthways directly beneath the heat absorbing plate, so that there is maximum contact surface between the two components. The central water heating system is connected to the flat plate collector, so that water flows through the copper pipes. Therefore, when sunlight heats the heat absorbing plate, heat gets conducted through the copper pipes, heating the water flowing through them. The heat absorbing plate together with the copper pipes are enclosed in a well-insulated box in order to maximise the efficiency of the system.
Similarl to other solar heating technologies, flat plate collectors can be installed on the roof of a property. In some cases, flat plate systems can be mounted independently outside the house, for example in the garden. A flat plate collector system requires a hot water tank for the hot water to be stored.
Advantages
- Low Maintenance Cost: Flat plate collectors have lower maintenance costs compared with other renewable energy systems.
- Low Operational Costs: As flat plate collectors use solar energy to produce hot water, their operational cost is essentially zero.
- Low Capital Costs: Flat plate collectors are one of the cheapest solar heating technologies.
- Environmentally Friendly: Flat plate collectors account for no CO2 emissions, as they provide clean, green energy.
- Renewable Energy: Solar energy is supplied by nature and does not have a limited supply.
- Support: Flat plate collectors can be easily integrated with other heating technologies in order to meet the household demands. (Other than combi boilers)
- Cold Weather Performance: Flat plate collectors can perform in a cold environment.
- Incentives: Flat plate collectors are eligible for the Renewable Heat Incentive, meaning that homeowners can get a part of their investment back.
Disadvantages
- Lower Efficiency: Flat plate collectors are less efficient than other solar hot water technologies, such as evacuated tube collectors.
- Need for a Backup Heater: Although flat plate collectors are able to produce hot water during winter months, a backup heater might be needed on some occasions in order to meet household demands.
- Incompatible with Combi-Boilers: Solar hot water systems are not compatible with combi-boilers.
- Less Compact: Flat plate collectors require more space compared with other solar hot water technologies.
- Technical Limitation: Given the absence of optical concentration in flat plate collectors, the area from which heat is lost is great. Therefore, high temperatures cannot be attained.
Photovoltaic/Thermal Hybrid Solar Collector
Overview
A photovoltaic/thermal hybrid solar system, or PVT system for short, is a combination of both photovoltaic and solar thermal components which produce both electricity and heat from one integrated system. Given that the sun’s energy is a renewable source, the heat and electricity generated by photovoltaic/thermal hybrid systems are clean and carbon free. Photovoltaic/thermal hybrid solar collectors have been developed since the 1970s and represent an ideal method for producing both electricity and heat for a domestic property.
What is a Photovoltaic/Thermal Hybrid Solar Collector?
A PVT collector combines photovoltaic and thermal technologies into one system in order to produce both electricity and hot water. A PVT collector consists of several layers.
The first layer consists of the photovoltaic module, which is made from photovoltaic cells. When sun rays shine over the silicon photovoltaic cells, an electric field is created, and hence electricity is produced. As a result of this process, the PV module retains heat, which is conducted through the thermal grease and the absorber to the serpentine tube, which is connected to the central heating system of the property. Therefore, the water flowing through the serpentine copper tube heats up and is then stored in the hot water tank.
There is a large variety of Photovoltaic-Thermal Hybrid Collectors designs, as these depend on the different applications required. Some systems have a greater focus on generating electricicty, while others have a greater focus on generating heat.
Advantages
- Low Operational Costs: As PVT collectors use solar energy to produce hot water and electricity, their operational cost is essentially zero.
- Environmentally Friendly: PVT collectors account for no CO2 emissions, as they provide clean, green energy.
- Renewable Energy: Solar energy is supplied by nature and does not have a limited supply.
- High Efficiency: Photovoltaic-thermal hybrid systems are more efficient than standalone solar technologies.
- Two in One: PVT collector systems combine the advantages of both photovoltaic and thermal collector systems into one technology.
Disadvantages
- High Capital Costs: PVT collector systems are considerably more expensive than either photovoltaic or thermal systems.
- Interdependence: The operation of the photovoltaic system depends on the operation of the thermal system, and vice-versa.
- Weather Dependency: Despite being more efficient than other technologies, PVT collectors still depend on the weather.
- Incentive: PVT solar collectors are not one of the heating systems which qualify for the Renewable Heat Incentive scheme.
