Optimisation of solar cells in DC grids
Ferroamp’s Solar String Optimizer (SSO) is used to connect solar cells to the EnergyHub system. When the SSO won the prestigious innovation award in the solar electricity class at the 2020 Intersolar conference, they called it the first solar cell converter for DC grids. The SSO is a smart further development of the traditional MPPT input in traditional inverters. The advantage of connecting solar energy to Ferroamp’s DC grid is that all solar electricity, regardless of where the panels are installed and what kinds of panels are used, is connected as a shared production resource, so that we can use smaller cables and also control how we best use this energy. The solar string optimizer is a unique product on the market and has been developed to take full advantage of the possibilities offered by Ferroamp’s EnergyHub DC grid. Our solar string optimisers are market leaders in terms of function, efficiency, flexibility and safety.
The solar string optimizer offers a new level of flexibility in planning, installing, monitoring and maintaining solar cell installations. Each optimiser has built-in MPP functionality, which guarantees that each panel generates maximum production, and it also has a number of built-in safety features. For example, it shuts down completely in the event of a power failure or when a fireman’s switch is used. The SSO monitors and shuts down “its string” in the event of a fault that causes dangerous leakage current to the ground, such as a cracked or broken panel. Installations can be performed with 1-64 strings with maximum safety and control, and can also be expanded when demand increases.
An expandable system
Installation is easy to perform, by connecting the SSO units to the DC link with two wires. A high DC link voltage allows for thin wires and much simpler cable management. The DC link also means that fewer cables run from the panels to the inverter. The SSO connects its own solar loop and makes sure that it works in the system. If there is a need to add more solar cells to new surfaces, this can be added to the same DC grid. This enables gaps in production hours to be filled or new surfaces to be covered by, for example, solar cells as sun protection. The new solar cells are easy to add to the system. EnergyHub takes care of control.
Smart and dynamic control
The SSO is fitted with control electronics that enable automatic remote control. The DC/DC converter automatically shuts off and disconnects the solar string if the EnergyHub is disconnected. The SSO is controlled by a small local computer that knows what is expected at any given moment. A Ferroamp system can, for example, scale down production if necessary to protect a main fuse. A facility that normally has local loads that consume the energy produced may, in certain situations, need to be slowed down if these loads are not working or are in operation. This can be important for industrial premises or schools, which generally want solar production that can be used in normal operation, but that end up in the risk zone for producing too much during weekends or holidays. The EnergyHub system can channel energy to batteries when the output is too high, or you can direct other loads to be stored in hot water. Finally, it can feel good if the SSO itself can downscale if needed,
The SSO can handle string voltages up to 720 Vmpp, it can handle up to 12.5 Ampp and has an efficiency level of over 99.5%. A high DC link voltage allows for thin wires and much simpler cable management. The DC link also means that fewer cables run from the panels to the inverter.
Each SSO can only deliver 12.5A, which means you can handle all installations with a 1kV cable with three conductors (plus, minus and a ground conductor) 3 x 2.5mm2 between the SSO and our DC distribution centre. It is safe, neat and easy to install.
Most of the EnergyHub system is based on software. This allows new features and enhancements to be downloaded over the internet to enhance or customise its function as required.
The SSO has a built-in residual current circuit breaker that disconnects the loop from the system if it detects any electrical fault in the solar panels. This can happen in the event of production faults, settlements or if, for example, someone throws stones at the panels. The SSO contains relays that disconnect the solar cells physically if the installation is disconnected, or if a remote-controlled emergency switch is being used, should it be needed in the event of a fire, for example. This cuts the power to the entire DC grid.
Thanks to the technology built into the DC grid, we can use fuses for all cabling. This is a big difference compared with other solar inverters, where the cables between panels and inverters can cause an arc if the insulation were to be damaged. If you place the SSO as close to the panels as possible, in principle all cables will be safer. Electricity is always dangerous, but a Ferroamp system is in principle as safe as an AC grid with fuses and section switches.
The SSO can be mounted right next to the solar cells, and it can withstand both water and heat. With the SSO next to the panels, the installation is as safe as possible.
SSO Single 8kW
SSO Single 8kW is used on solar strings up to 8kW.
Ferroamp’s solar string optimizer delivers the same voltage (760V) no matter what you have in it. This means that multiple solar loops can be connected in a DC grid. The SSO can handle a mixture of panel surfaces at different radiation angles. How many solar panels can be connected to each solar string optimiser depends on the panel’s specification.
Thanks to the latest silicon carbide technology, the efficiency is as high as 99.5% for maximum utilisation of solar energy. Connect directly to Ferroamp’s DC grid, so that solar energy can be stored or used immediately. This provides the greatest possible flexibility with the least possible losses.