Making the Most of your Solar Panels

If your home has solar panels – installed by you, or your landlord or through a ‘rent-a-roof’ scheme – you may need to re-think the way you consume electricity in order to reap the greatest benefit.

Making the most of the free electricity from your solar panels may involve changing your routines and thinking differently about energy use. It may mean planning ahead: for example using your washing machine or dishwasher during the day rather than in the evening.

Solar photovoltaic (or PV) panels convert the energy in sunlight into electricity, and this is effectively free electricity that can be used in your house (once the cost of installing the panels has been taken into account, of course). Surplus electricity is exported to the grid to be used by somebody else.

However, when the sun isn’t shining, or when you’re using more electricity than the panels are producing, the extra will be imported from the national grid, as it was before you had the panels, and you will be charged for it by your energy supplier at the normal rate.

Solar panels: use them wisely to make them pay

A typical 2kWp (2000W) household array of solar panels will produce 2kW under optimum conditions, that is:

• if the panels face more or less south and are sloped at the right angle to receive the most sunlight
• if the panels are free from shade;
• if it’s a sunny day.

So, at noon on a bright June day they could be producing close to 2000W, while on a cloudy afternoon in December that value might be nearer to 100W. In order to know how to use this free energy wisely, you need to have an idea of how much electricity different appliances use.

Let’s look at some typical power ratings:

• Low energy light bulb: 15W
• Fridge: 100W
• Laptop: 150W
• Microwave: 750W
• Washing machine: 2500W (2.5kW)

And let’s assume your solar panels are generating a steady 1000W (1kW). Of this, 100W will be used by the fridge – though not continuously since it switches itself on and off according to need – leaving 900W for other appliances. So based on the ratings above you could use your 750W microwave for free and still have 150W available to run lower power appliances, such as lights. If you wanted to  run your washing machine you’d pay for the extra 1600W that you need and that the solar panels can’t generate.

It follows that 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.