When days are really dull in winter generation will probably be accounted for largely by base load (central heating pump, fridge, freezer etc., sensors, displays etc.). When there is a little more than the minimum coming from your system one can step-up the power usage to include re-charging torches, toothbrushes, radios and laptops. During bright or sunny conditions you can use the excess electricity to switch on more thirsty electrical appliances, heat up hot water, or provide extra heating to your house. A good place to start is dishwashers and washing machines as you have control and flexibility over when they are run. Try to save up washing as much as possible for the sunnier days, this works out well as sunny days are great for then putting the washing out to dry.

You should stagger the use of high-wattage appliances to make the most of the free electricity available. This might mean waiting for your washing machine to finish before running the dishwasher. That way you can stay within the maximum power output of your system and avoid drawing extra power from the grid.

Other ways to get the most out of your system include:

• Switch usage times about e.g. Cook evening meal during day
• Save winter drying/ironing for good generation days
• ‘Hoover’ when the sun shines
• You could use a timer on your immersion heater that comes on when your solar PV is likely to be at maximum production rate but your house consumption lowest, i.e. mid-day mid-week in summer when your all out at work so your exporting to the grid but during the winter months it’ll make little difference.
• You might also consider using any excess electricity to top up the likes of electric storage heaters. If you do this you have to be particularly careful not to use more electricity than would otherwise be exported if you currently buy your electricity on Economy 7 or 10. This is because any extra electricity consumed during the day will cost you more than electricity consumed during the cheaper rates available at night using Economy 7 or 10 – making you worse off.
• Using a heat pump is likely to ensure you use all generation in winter, early spring/late autumn

How do I know what I’m generating and what I’m using?

As you can see from the above it can be a juggling act to keep varying use in line with varying production. You may be able to nip into your loft to check your system’s output on your inverter but for many this is simply not practical. It is also possible to check your own domestic electric meter. If you are only using power from your PV system the digits on your electric meter should not be moving. If the digits are moving backwards it’s a sign that you are exporting power to the grid but if this is the case you’ll need to contact your electrical supplier and get them to come and install a different meter. A digital electric meter will have a flashing red light when you are importing electricity from the grid. If you have a ‘key’ or ‘pay-as-you-go-meter’ you’ll need to contact you electric supplier to confirm that it’s compatible with a solar PV system.

Energy Monitors

The most accurate and convenient way to keep track of what you’re producing is to install an PV energy generation monitor in your house, typically in the kitchen or utility room. These can be bought for around £100. A typical example is the Geo Solo1 which will give you much the same information available from your inverter. Some models are straightforward to install but others may need to be fitted by a professional electrician. You can even have your system connected remotely to your computer, allowing you to monitor your panels over time. If you don’t own the solar panels, check with whoever does that it’s OK for you to fit a monitor.

In order to measure exactly how much power you are using you will need to install an energy usage monitor. Many homes now have energy monitors that show how much electricity is being used at the present time, as well as how much was used last week, last month etc. They are wireless devices that can tell you useful things like what your current energy use is costing you. Basic models can be bought for around £30 although you may find that your local library can lend you one to try out.

By using a PV energy monitor you can see what is actually being produced at a moment in time and then decide what you are going to run. Perhaps it would help to keep a list of the power ratings of your appliances next to your monitor to help you decide what to switch on and when. If you also install an energy usage monitor next to you generation meter you can accurately ensure that the electricity you are using is matched by what you are generating. Finally, don’t forget that it’s always pays to keep an eye on what the weather is doing.