Many areas have an unreliable grid supply with frequent power cuts. Using a battery store and inverter/charger gives back-up power allowing critical loads to be run until the grid supply is restored when the batteries can be re-charged. Including a solar array or wind turbine enables loads to be run for extended periods without the mains.
All loads can be run on conventional 230Vac wiring. Usually it is not feasible to size the system to run all loads so heavier or non-critical loads (eg. air conditioning or heating) should be separated off and only ever run from the mains.
Systems vary from small inverters to run individual appliances such as central heating pumps or computers to bigger systems for households or other premises.
In many instances power cuts experienced may only be of short duration. In which case a reliable standby system need only consist of an inverter/charger and battery bank. This enables essential loads to be maintained from the battery until mains power is restored which then replenishes the battery.
The best systems give battery back-up maintained by wind & solar generation but allow this generation to be grid connected whilst the grid is available. This ensures full benefit is always obtained from on-site generation but power cuts can be averted.
In order to protect linesmen working on the grid system ‘Anti-islanding Protection’ must be included.
This is sized to cover load consumption for the maximum length of power cut expected.
Deep cycle batteries designed for this type of application should be used.
PV Solar Generation
Adding wind or solar generation allows the battery to be kept charged and enables loads to be run for longer (even indefinitely) without mains power.
If the possibility of extended power outages is envisaged then a back-up diesel generator can be incorporated to maintain supplies and to replenish batteries .