So, you are conducting research into getting solar panels. Rightly, you want to know how much they will cost to install, and how much money they’ll save you. Generating a cost for installation is fairly easy – companies will provide you with quotations. The products and service they are offering might vary, but it will good you a good idea of the investment required.

But how much money the panels might save you is not a straight forward question to answer. There are 2 elements to this.

• The first element is a semi-technical question: Provide an estimate of the likely power generated by the panels.

Using historic data on weather and data on irradiation levels in your region of the country, together with factors such as shading, azimuth, and the power rating of the panels, an overall average for the year can be provided with reasonable accuracy. On any given day and at any given moment, however, output will vary depending on whether the sun is shining.

• The second element is as much about behaviour as anything else: Provide an estimate of how much of the solar energy I’ll use and how that self-consumption reduces the amount of energy I’ll need to buy from the Grid.

Once you have solar panels you may well find that your behaviour changes. For instance, if you currently routinely put the dishwasher on in the evening after dinner, in the future you might put it on during the afternoon of the following day.

To illustrate this point, Zap Map (the Electric Vehicle charger mapping service) recently released some research which found that EV drivers are seven times more likely to have solar panels on their home than non EV drivers. So by taking this first step into Solar Panels, you become much more likely to install a Battery Storage system, buy an EV and perhaps even get a Heat Pump in the future.

To answer the self-consumption question, we are really answering that question blind unless we know how much energy we use overall in our home. The National Grid ESO report into Future Energy Scenarios included this useful graphic. It shows (using Terawatt hours on the Y axis) how much energy as a country we use in our homes. 2 key points stand out. Firstly, it confirms that space heating and water heating make up the huge majority of our energy use in the home. And secondly that electricity usage is concentrated on the use of appliances – lighting and cooking are only a tiny fraction of the overall energy usage.

And sticking with appliances, the big three involve generating heat: Washing Machine, Dishwasher and Tumble Dryer. Electrical energy saved by turning off phantom devices, or whether you have a modern A+ rated TV makes a tiny difference in comparison with 30 minutes of Tumble Drying.

You have managed to confuse me. What should I do now?

Using the Solar Energy Calculator from the Energy Saving Trust is a useful first step. But it’s way of dealing with all the complexity referred to above is to simply ask when during the day you are at home. But we have established that having the lights on all day uses less electricity than one cycle of the tumble dryer – so this isn’t actually a very useful metric.

Brimstone Energy will walk you through the decision making process, make things as simple for you as possible, and help you optimise your decision.

And finally……with a Home Storage Battery, the calculations change dramatically – in your favour. Because apart from anything else, it takes the biggest variable out of the equation – behaviour. You can put that dishwasher on whenever you like!