Making Your Generation Work For You
These clever little boxes actively monitor what is going on with your PV produced energy - if you don’t use it, you lose it. Grid connected PV arrays will dump anything you do not use within your home or business directly to grid – meaning you could be managing your yield better. Immersion controllers automatically divert this otherwise ‘wasted’ electricity into your hot water cylinder via the immersion element. This not only maximises your return from your PV array but also keeps your hot water cylinder topped up ready for use. Second generation immersion controllers feature outputs for more than one immersion element and conductivity to wireless stat units allowing you to see exactly what you are using from your PV.
These devices such as the Wattson meter, allow you to see the amount of electricity you are drawing from the grid, meaning you can be proactive in managing your out goings as well as giving you a visual aid prompting you to make use of any PV generation you would otherwise be wasting.
Optiplug – Working in tandem with the original Wattson, Solar Plus and Professional models, this intelligent socket switches on your appliances when your PV system is generating spare electricity. The smart socket will learn how much electricity is required by the appliances that are plugged into it, only switching on when enough electricity is available, and turning off when electricity is no longer free. The Optiplug can be used with any device that uses or charges and does not require a manual switch on or being turned on and off intermittently such as an air conditioner or electric heater unit, heated towel rail or even an electric car charger.
A voltage optimiser is simply a transformer and electronics used to narrow the incoming electricity voltage to a lower and more stable level. Your incoming supply in the UK must be between 216V to 253V, generally electricity companies like to work at the top end of this as with higher voltages come less losses in the distribution network. A voltage optimiser will typically narrow this to a more constant level of 220V. The claim made by some is that this reduction in voltage, from say 250V to 220V, results in an electrical saving (around 13%), however, your electricity meter measures both Volts and Amps to produce Kwh which is the unit you will be charged on.
Most of the energy hungry devices in your house use electricity to produce heat; kettles, ovens, hobs, microwaves, electric showers etc. reducing the voltage that these devices receive will either mean that they will draw more amps or that they will need to be on for longer to achieve their function, therefore there will be no saving by using voltage optimisers for these devices. The same can be said for anything that uses a switch mode power supply such as, phone charges, TV’s etc will simply more draw current if the voltage is reduced. Devices that can benefit from voltage optimisation would be fans and pumps. A fridge or freezer could potentially benefit from the lower voltage but the saving is very low, for a traditional large ‘A’ rated fridge freezer the saving could be a maximum of £5 per year. You can’t change the laws of physics; Power = Volts * Amps, but for most devices in the house reducing the voltage will either mean the current is increased or the device needs to be used for longer and therefore there is no saving.
Independent studies, that have been completed with voltage optimisers, have shown the mean saving is around 5% over a year, so at least a 20-year payback period and that assumes the optimer itself lasts that long.
The other angle often used to sell these systems is that “it will improve your PV generation output”, the only way that a voltage optimiser could affect the output from a PV system is if the supply voltage at the property exceeds the 253V level during a sunny day. If this happens the PV inverter will switch off and then restart, hence will lose some generation during this time. All PV systems installed are approved by the DNO (District Network Operators - the companies responsible for the power grid) either because the system is less than 3.68Kw (inverter size 16A) in which case there is a default acceptance of the system, or the installed size is greater than this figure, in which case your installer would have sort specific permission to install the system - either way, if your voltage is too high for the inverter to work all the time, then it is the responsibility of the DNO to change the transformer tapings suppling your property to enable it to work effectively. This comes at no cost to the homeowner.
To save money on your electricity bill there are only two real options; use less or generate more. To use less the biggest and easiest saving is to replace all your light bulbs for LED’s, yes this is a little boring but it works and the savings will usually pay back in a year or 2. To generate more, either fit PV or extend or upgrade your current system making use of solar optimisers or a battery storage solution.
There is now a danger that “Voltage Optimisers” will be mis-sold as "Solar Optimisers" such as the SolarEdge system. True solar optimiser solutions involve the installation of individual DC optimisers to each solar panel and changing the inverter. Unlike voltage optimisers they will always improve the output of your PV system from between 5% to 25%.