Optimising self-consumption after net metering

Under the net-metering scheme you could offset the power you fed back against the power you drew. A kilowatt-hour that ran your meter up during the day, you simply took off again in the evening. As a result it made little financial difference whether you used your solar power directly or only fetched it back from the grid much later.

That scheme is being phased out, expected in 2027. Always check the current state of play, because the politics have shifted the start date before. Once net metering ends, the rule is: what you feed back, your supplier buys back at a feed-in rate that is often a good deal lower than what you pay to draw. Some suppliers also charge feed-in costs.

The upshot is simple. A kilowatt-hour you use yourself at the moment your panels generate it is worth more than that same kilowatt-hour you feed back and buy back more expensively later. Hence the new rule of thumb: use your own solar power yourself as much as possible, while the sun is shining.

The cheapest step costs you nothing: run your big users when your panels generate the most, roughly between 10 am and 4 pm on a clear day. Think of the washing machine, the dryer and the dishwasher. Many appliances have a delayed start or a timer, so they switch on by themselves in the middle of the day.

Your hot water is a rewarding user to shift too. If you have an electric hot water tank or a heat-pump water heater, set it to warm up during the day instead of at night. A heat pump for your heating can be steered the same way: let it work a bit harder during the day and keep the home warm, so you have less to top up in the evening.

If you drive electric, the car is often your biggest opportunity. An average charge draws more power than a whole day of household use. Charge at home during the day on your own sun and you turn a lot of your own generation into miles in one go. If the car is at work during the week, smart charging at the weekend or a dynamic rate on weekdays helps.

Timing everything by hand is a hassle. That is why there is more and more technology that does it for you. A smart EV charger can be set to charge only with the surplus your panels are supplying at that moment. If the sun is strong, it charges faster; if a cloud comes over, it eases off. That way you charge mainly on your own power and not on expensive grid power.

A step further is an energy management system, also called a HEMS. Such a system looks at your generation, your consumption and sometimes the weather forecast, and steers your EV charger, your home battery and sometimes your heat pump accordingly. It takes the puzzle off your hands and tries to push your self-consumption as high as possible automatically.

With a dynamic energy contract you pay the current market price each hour. Around midday, when the whole country is generating solar, power is often cheap or even negatively priced. That is the moment to charge or heat the hot water. A dynamic contract does need some attention and does not suit everyone, but combined with smart control it can make your generation pay off better.

What you generate during the day but do not use directly goes to the grid. A home battery stores that surplus, so you use it yourself in the evening and at night instead of feeding it back. That raises your self-consumption considerably, often from around thirty per cent to sixty per cent or more, depending on your situation.

Whether it pays off depends on the price of the battery, your consumption pattern, your feed-in rate and any extra return from smart charging and discharging on a dynamic contract. The payback time has shortened in recent years, but it remains an investment you should calculate carefully. We would rather keep you honestly informed than make fine promises.

Worth knowing: a home battery needs space in your fuse box and a safe connection to NEN 1010. Sometimes an adaptation or extension of your box is needed. In our separate articles on the home battery and net metering we work the weigh-up out further for you.