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Renewable energies: the solid state relay solution
We are more and more confronted with environmental issues linked to air pollution, greenhouse gas emissions, global warming, and the increase in the cost of electricity and gas.
In order to solve these issues, the global market is getting more and more focused on renewable energies, representing a huge potential.
Among numerous technologies used in the renewable energy industry, solid-state commutation is highly used in many processes, from the manufacturing of solar panels to the de-icing of wind turbine blades.
This article will introduce you to the most frequent solid-state-relays applications on the renewable energy market.
In order to capture solar energy, solar panels are equipped with photovoltaic cells made of silicon. Photovoltaic cells capture sunlight and transform it into energy allowing it to be directly used on a precise system, redistributed to the electricity network, or stored on batteries for future utilization.
Photovoltaic cells manufacturing
Photovoltaic cells are electronic components that allow to capture sunlight and transform it into electric energy. These cells are made of silicon.
Solid-state-relays are very useful in the majority of the manufacturing process of solar cells.
Silicon ingot squaring
Raw material (silicon), is first transformed into ingots.
Wafer slicing and cleaning
The ingots are then sliced in very thin layers (approx. 250 µm). These layers are called wafers. Once the slicing is done, it is necessary to clean the wafers in order to remove damaged silicon from the slicing. Solid-state-relays are used in order to control the heating elements in the wafer cleaning machines.
celduc® products used in wafer cleaning machines :
Diffusion / Treatment / Doping
Diffusion furnaces (thermal treatment), are used during the thermal annealing process, allowing to activate dopants by oxidation, and chemical vapour deposition. These furnaces will heat the wafers at temperatures between 800 and 1200 °C.
Solid-State-relays are then essential to precisely control the heating elements in the furnace.
celduc® products used in diffusion furnaces :
Annealing of the metal contacts of the wafers
A fast-firing furnace is used in order to burn and sinter the metal contacts of the solar cells. Heating is generated by short-wave infrared lamps, controlled by solid-state-relays. A burst control mode allows for precisely setting up the power of the load.
celduc® products used in fast-firing furnaces :
In order to guarantee the optimal performance of solar cells and reduce the light absorption loss, an anti-reflective coating in applied on the cells with the help of special machines.
Solid-state-relays are useful to control the heating elements in anti-reflective coating machines.
celduc® products used in anti-reflective coating machines :
Solar cells are then placed in an aluminium frame, forming the solar panel.
A solar farm is a grouping of many solar panels on big land. It is directly connected to the electricity network, allowing many households and companies to be supplied with green energy. Solar panels generate direct current (DC). It is then necessary to convert it into an alternative current ( AC).
Solid-state-relays are useful to protect solar panels against winter overvoltage, to protect them from a potential no-load of the converters, and inefficiency boosters allowing to increase the solar panels’ power.
celduc® products used in these applications :
A solar tracker is a motorised robotic arm allowing to orientate solar panels towards the sun to increase the energy production. Trackers can follow the sun east from west and regulate their height to catch more sun rays. DC inverters are used in order to control the motor of the robotic arms of the solar trackers.
celduc® products used in solar trackers :
- XKRD range (four Solid state relays pre-wired as a reverser)
- SGRD range(DC inverters equipped with all control electronics, short-circuit protection and a lockout to prevent the two rotation directions from being gang-operated)
Energy storage systems
Most of photovoltaic systems have integrated batteries that store the electricity generated by solar energy for future uses, when the sun exposure decreases for example. Solid-state-relays are used as an intermediary between the solar panel and the storage battery and is also used to discharge the battery once it is too full.
celduc® products used in energy solar systems :
Wind energy with wind turbines
A wind turbine produces energy generated by the wind, spinning its blades connected to a rotor, itself connected to a generator. The generated energy is then redistributed in the electricity network by underground cables.
Turbine blades manufacturing
AC solid state relays are used during the manufacturing of turbine blades during fibre and compound manufacturing, and blade moulding.
Turbine blade curing process
Because of the environment they are surrounded by (frost, insects, sand, salt, etc.), turbine blades can develop small cracks and holes over time. It is then essential to repair them in order to avoid bigger, irreversible damages during a process called the curing process. In order to do so, heating blankets are used to heat the blades between 60 and 80 °C.
Solid-state-relays are then used in order to control the temperature of the heating blankets.
celduc® products used during the curing process:
Wind turbines de-icing
Frost can highly damage wind turbine blades, but, the highest energy production potential is in cold environments. Indeed, winds are stronger and apply greater pressure to the blades.
It is then really important to install a de-icing system on the blades to avoid any damages that would decrease the turbines’ productivity.
Wind turbine de-icing systems are composed of 3 different steps. First of all, the system must detect the presence of frost, then the blades must be heated to melt the frost (heating elements directly integrated into the blades), and finally, the system must control the efficiency of the de-icing process.
Solid state relays are then used in the blade de-icing system to control the heating elements directly integrated into the blades.
Energy storage systems
Batteries allow storing of the energy generated by wind turbines. These batteries can be used in isolated areas, or to prevent a network disconnection.
DC solid-state relays are then used to switch the charge and discharge of batteries.
Biomass regroups every organic matter that can be transformed into energy. Biomass regroups green substances (wood, vegetable waste, etc.) and animal substances (food waste, animal waste, etc.).
Once these organic matters are burnt, they transform into energy and can be used to generate heat.
Pellets boilers allow heating of the water in canalisation systems by combusting pellets (compressed wood). The hot water is then stored in a tank or immediately used. Solid-state-relays are used in pellet boilers in the cleaning, ignition and fan & valve systems.
A growing market
Following global awareness regarding the need to use renewable energies to stop pollution and global warming, the market for renewable energies is developing more and more, year after year.
Renewable energy systems must be highly reliable with high service lives, which is why solid-state-relays are essential to the market’s development.