Energy Saving Voltage Optimisers

Voltage optimisers are energy saving devices with a proven track record in the UK. In the UK the historical mains supply voltage from the National Grid was 240Vac ±10% and this was lowered to 230Vac for harmonisation with Europe. The widespread deployment and concentration of multiple solar PV and wind turbine installations has helped to push up the average mains supply voltage to most buildings and readings above 250Vac per phase are common leading to increased energy usage and higher electricity bills for those customers.

Voltage Reduction Technologies

Voltage optimisation devices are available for domestic, commercial and industrial sized installations and reduce electricity bills through voltage reduction. There are several types of voltage optimiser design including fixed voltage adjustment and automatic, electronically regulated technologies. The fixed voltage type tend to use toroidal transformers are and suitable for smaller buildings (up to 100A) including domestic and retail shops where they can be installed into single and three phase installations. Larger sites including industrial manufacturing complexes, retail and supermarket outlets or hotels may require a more sophisticated voltage reduction solution based around auto-tap-changing transformers, with advanced electronic control circuitry.

Voltage optimisers must be installed by a suitably qualified electrician or electrical contractor. Whilst domestic unit installations are relatively straight forward with the installation taking place close to the builder income and distribution board, larger installations will require a desktop and field-based survey. The reasons for this are that on larger sites the load mix and cable distance must be taken into consideration to maximise savings, identify the local mains supply voltage and that required by the loads on site.

The Carbon Trust

In the UK, the Carbon Trust provides funding for voltage optimiser projects. Loans with enhanced capital allowances are available form projects from £3,000 to £100,000 in value which are repayable within a project payback period of up to four years. The loan is based on the amount of carbon dioxide emission that can saved by the project. The Synchronised Power team can manage the complete financial application and process for sites investing in voltage optimisation.

How Voltage Optimisers Work

Voltage optimiser operation uses voltage correction technology to reduce the AC main supply voltage supplied to connected loads to reduce their power and energy usage. The following example helps to explain the concept in terms of Ohms Law.

Voltage = Amps x Resistance (V=IR)

Power = Volts x Amps (P=IV) Watts

The table below shows the saving in energy (kW) achieved using voltage reduction from 250Vac to 220Vac for a 100A load.

Situation Mains Power Supply Voltage Current Power Saving
No Voltage Optimiser 250Vac 250 × 100 = 2.5A 250 × 100 = 2.5kW
Voltage Optimiser Installed 220Vac 220 × 100 = 2.2A 220 × 100 = 2.2kW 0.3kW

The example shows a saving of 0.3kW or in terms of how we are billed electricity 0.3kWh. Over a 24-hour period the saving is 24×0.3kWh=7.2kWh or in a year 109.5kWh.

Voltage Optimisation with Solar PV Installations

Voltage optimisers units can improve the return on investment in solar PV (Photo Voltaic) installations to generate further energy savings and cost reductions.

Firstly, the voltage optimiser can reduce the amount of energy consume within the building. With the building using energy generated from the solar PV installation less energy must be imported from the local grid. Secondly the voltage optimiser will help to protect connected loads from the wear and tear associated with higher mains power supply voltages.

Solar voltage optimisers can be retrofitted to existing PV installations for sites that want to further reduce their energy usage. The ideal installation slot for the device is between the consumer unit and its AC power source.

Solar PV Voltage Optimiser Savings

Energy savings can be achieved through the installation of a solar voltage optimiser with a PV installation. The following savings are based on a 7.5% voltage drop (242Vac to 224Vac):

Type Load
Appliances with Motors A-rated Freezer/Refrigerator 16%, 3-speed heat pump 15-18%
Heating Resistive heating 14%*
Lighting Compact Fluorescent Lighting 11%, Sodium/Discharge 15% Halogen 12%, High Freq Fluorescent 0%
Motors Air Compressors 12%, Circulation pumps 12%, Fans 12%, Vacuum cleaner low power 24%, Vacuum cleaner full power 16%
TVs/Computers CRT 5%, Plasma/LCD 0%, PC 4%, Laptops average 6%, Radio 9%, Printer 7%, Scanner 12%
Consumer Electronics DAB Radio 5%, DECT phone base station 30%, ADSL modem and wireless router 5%, HiFi 13%

*thermostatic control will result in a much smaller saving.

Please contact us for further information on our voltage optimiser range or a free desktop or site survey. We can also maintain third party unit installations.