Solar PV System with Energy Storage

Comparison of Conversol 5KW Off Grid Inverters-48V Battery
August 15, 2018

Solar PV System with Energy Storage

Installation of 8x solar panels on UK property, 2280Wp total power

The new installation of a  Solar PV System energy storage (2,280Watt) is feeding in parallel with the old grid tie system the home appliances of a 3 bed room property in Coventry (UK).

The first small PV array was installed in 2013 amd has 1200Watt output power. The energy is connected  to a feed in tariff meter. The energy is consumed directly consumed by the home appliances during the day. Any excessive power is fed back to the national grid.

The system works fine without any faults so far but there is no way to store the extra power. In cloudy days or at night the electricity is supplied exclusively but the energy provider.Installing another 8 solar panels on the south facing roof, the dependence on energy supplier will be reduced by an extra 90%.

what does it means in real numbers? A average household consumers 8kWh-10kWh of electricity per day (heating on gas, not electric). From May to August, the daily production is approximately 12-26kWh, in the winter, the production drops to 6kwh-8kWh per day.

We captured some real date from in summer, autumn and winter, it is evident that the solar installation is capable to cover all the electrical requirements.  For the cloudy days, the excessive power is stored in the battery bank, a sunny day with over 20kWh consumption is now wasted any more. The energy will be used when it is needed the most, the right time and the right day.

The following real-time power generation graphs shows the two systems running harmoniously together

Energy yield of solar panels in October 2018, installed power 3480Wp

 

Green energy produced by solar panels in Coventry, UK. The graph was captured in June 2018

 

 

 

The hybrid 3kW inverter with on grid and off-grid function connected to the 8x EGING PV panels.

With the advent of smart hybrid inverters, the photovoltaic industry moved to a new level of standards. For first time we are talking about bi-directional flow of energy. That means, that solar power is not moving from the solar panels back to the grid only. This is a summary of functions:

  • Power from the panels to the battery
  • From the battery to the ac appliances
  • From the panels to the loads & battery
  • From the grid back to the batteries & appliances
  • From the batteries to ac load if the grid fails (off-grid operation)

Nighttime
During the night the Voltasol is disconnected from the grid. The home is powered by energy stored in the battery. The Voltasol will reconnect the grid when the battery is discharged.

Battery charging
The next day, when the PV array produces sufficient power to supply the loads and to start charging the battery, the Voltasol will control charge current to absorb almost 100% of the surplus photovoltaic power.

Discharging during the day
When PV output is reduced (cloudy day) or most of the appliances/loads are turned on, resulting in no extra/excessive PV power available, battery charge process will stop. Inadequate PV power will be supplied by power from Voltasol. In case of more power is required, the inverter will get the extra energy from the grid.

Battery fully charged
Once the battery is fully charged, additional loads (for example the water heater) can be switched on, or surplus power will be exported to the grid.

UPS function When the grid fails, Voltasol will continue to power the home.

 

 

Solar Energy Power Cycle: Production, Storage, Consumption

Installation of 8x solar panels on UK property, 2280Wp total power

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Schletter mounting kit for roof, aluminium rails and steel brackets. Solid and water tight installation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soladin 1000 Web with intelliweb online monitoring connected to 230V grid. The inverter converts solar energy from 5x Eging PV panels

Stefanos Kandilidis
Stefanos Kandilidis
Electrical & Electronic Engineer at Voltacon Power Conversion. He used to work at the renewables R&D department General Electric for 8 years.

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