Here is a brief synopsis of how PV works in conjunction with a battery and a hot water diverter……
Night time: Battery empty
Power taken from the grid
Day time: Battery Empty & House burning more energy than panels are generating
House is using 2kW of power and the panels are generating 1 kW of power. 1kW of power goes from the panels (via the inverter changing the PV power from DC to AC) onto the fuse board. The other power required to run the house comes from the mains. Therefore, your house is only pulling 1kW from the grid.
Day time: Battery Empty or not fully charged & House burning less energy than panels are generating
House is using 2kW of power and the panels are generating 3 kW of power. 2kW of power goes from the panels (via the inverter changing the PV power from DC to AC) onto the fuse board. Therefore, the power from the solar panels is running the house exclusively. The surplus power (1kW) goes through the inverter but remains in DC and is stored in the battery in DC.
Day time: Battery Full & House burning less energy than panels are generating
House is using 2kW of power and the panels are generating 3 kW of power. In the event the battery(s) is fully charged, all the power from the solar panels (in this case 3kW) is converted from DC into AC power and sent to the fuse board. This means that there is surplus power on the fuse board (1kW). The hot water diverter sensors on the fuse board detect this surplus power (1kW) and send ONLY the surplus power from the solar panels to the immersion heating the water from this surplus power.
Day time: Battery Full, House burning less energy than panels are generating & Hot water fully heated
House is using 2kW of power and the panels are generating 3 kW of power. In the event the battery is fully charged and the hot water is fully heated, all the surplus power (1kW) goes out onto the grid. You don’t get paid for feeding this surplus power onto the grid at the moment. It is planned to pay homeowners for this surplus power from Q2 2021, but they have not said what this rate will be.
Day or night time: Battery Full, House burning more energy than panels are generating & Hot water fully heated
House is using 2kW of power and the panels are generating 1 kW of power. If the panels are generating less than the house is using and the battery is fully or partially charged, the deficit that the panels can’t produce will come from the battery so no power is coming from the grid.
Day or night time: Battery Full & House burning more energy than panels are generating
House is using 2kW of power and the panels are generating 0kw of power. If the panels are not generating anything and the battery has sufficient power, all the power required by the house will come from the battery, so no power is coming from the grid.
Day or night time: Battery Empty & House burning power
House is using 2kW of power, the battery is empty and panels are generating 0kW of power. If the panels are generating nothing and the battery is empty, all the power required to run the house (2kW) will come from the grid.
Night time: Battery Empty & Night Saver Power tariff on the house connection
If your electrical bill has a night saver tariff connection during the winter months you can set the system up to be force charged from the grid during the reduced rate night saver tariff. This power can then be used to run the house during day time hours, especially during the winter months when PV is at its least efficient. This is particularly effective when you have 2 batteries (11.4kWh storage capacity) or more as this amount of power will run your home for a large proportion of day time hours
In conclusion, please note if you get an electric car the charger can operate in the same mode as a hot water diverter, sending only surplus PV power to the car.
Solar Home are Ireland’s longest established Solar Panel company. Finally, if you require more information or a quote from Ireland most experienced Solar Panel company give us a call any time on 091-848700.
