Solar Power Distribution System

In domestic solar applications without a local battery, a significant amount of the energy produced during the day is not used in the house, but rather fed back into the grid with a low compensation rate per kWh (typically in the form of a rebate). In the early morning and in the evening, when power consumption peaks, the solar panels do not deliver much energy and users have to buy energy at a much higher rate. With e-cars it will become even worse as the vehicles are typically not in the garage during the day and users will need to charge their cars at home overnight, essentially flipping the “duck curve” of traditional, daily grid utilization patterns. Read how RECOM helped a customer designing smart grid controller solutions.

Solar installations in domestic areas quite often only have solar panels and an inverter feeding energy into the house or into the mains utility grid. The downside is that energy bills can still be high as rates paid for energy fed back to the grid is much lower than the price per kWh when buying energy.

This is due to the daily energy consumption performance not matching the energy production of the solar panels. Consumption is higher early in the morning and highest consumption is in the evening when people are coming home from work and switch on many devices including lights. E-mobility applications have the potential to exacerbate this scenario as people charge e-bikes or e-cars outside of the peak sunlight hours.

In the evening, there is little to no energy coming from the solar panels in most regions. Intelligent systems can manage the surplus energy generated during the day with the use of energy storage and pragmatic control implementations. Smart grid solutions can use large, central batteries to store this energy to support charging EVs or e-bikes when no energy is directly available from the solar panels.

The system measures the average energy consumption, calculates energy needed by individual consumers and controls the distribution of energy from the solar panels to the batteries connected to the system. Smart systems can even control devices with high-energy consumption like compatible, “smart” models of washing machines or dryers to start when a surplus of energy from the solar panels is available. A compact, low power auxiliary AC/DC module was needed to supply the main contactor relay to activate or deactivate the system at the appropriate time and only when it was safe to do so.

RECOM offered a very small, 5W AC/DC converter module with an input range of 85 to 528VAC, qualified for applications requiring overvoltage classification III. This classification is much higher than standard, domestic products, and requires devices to withstand higher surge voltages, normally 4kVAC, and have enhanced safety features, such as wider gaps between the input and output. Installations of this type are often permanently connected after the incoming, utility-grade metering device and before the local control circuit. The very-wide-input voltage range of 85-528VAC means that the RAC05-K/480 can be safely used with 120VAC or 230VAC single-phase mains supplies or between two phases (277VAC or 480VAC) if no neutral connection is available.

International safety approvals and an integrated EMI Level B filter allowed easy deployment. Its full power -40°C to +60°C operating temperature and fully-encapsulated design makes it ideal for this application, which could be sited in unheated garages or outdoor carports.