Do solar panels work at night? Powering your home after dark

Do solar panels work at night?

The short answer to this question is no, solar panels don’t generate electricity at night due to the very nature of this technology, so for many people this begs the question: is it worth getting solar panels for my home, especially if I’m normally out during the daytime and only switch on and use most of my electrical devices and appliances in the evening when I return home?

One of the most effective ways of bringing down the cost of ever-increasing energy bills is to consider having solar panels installed. Even if you work all day and only come home in the evening, they are still worth having.

The key here is to understand things like how solar panel technology works, what time of the day your panels typically generate the most electricity, and whether battery storage could help you make better use of any surplus electricity. You might want to begin your journey by first looking at how much electricity solar panels generate throughout the year and then compare this to the average amount of energy your home typically uses.

The science: how solar panels work during the day but not at night

The short answer: No, when there is complete darkness, solar panels are ineffective and will not generate any usable electricity. They need sunlight to generate electricity. Photovoltaic technology in solar panels is capable of converting light into electricity.

The easiest way to explain how they work is that PV cells contain semiconductor materials that respond when photons (particles of light from the sun) reach them, which immediately releases electrical charges and creates an electric current that you can use to power the appliances in your home.

Therefore, after the sun has set for the day, solar panel electrical generation output decreases because daylight has faded and fewer photons are reaching the PV cells. Later on in the evening, when it’s pitch black and darkness has completely returned, your solar panels will stop producing electricity because there is not enough light to sustain meaningful solar generation.

This process is perfectly normal, and it doesn’t mean that there’s something wrong with your system. They just need natural daylight to work.

The good news is that even long after the sun has gone down, homes with solar installations can still use electricity to power their home and appliances. However, instead of this power coming directly from the sun, you need to find it from another source, such as the national grid or energy stored in a home solar battery.

You can learn more about the benefits of storing daytime solar for nighttime use on the official Energy Saving Trust website. The underlying message here is that your appliances don’t have to be powered by appliances at the precise moment electricity is generated.

You end up having three different choices with solar technology. You can either use the energy straight away, as soon as it’s generated. You can store some of it for later using a solar battery, or you can export surplus electricity.  

The important point here is that solar panels do not have to power your appliances at the exact moment they generate electricity. The choice is yours.

What time of day do solar panels stop working in the UK?

There isn’t a specific time of the day in the United Kingdom when all solar panels decide to just stop working just because there is no natural sunlight left in the sky. Several factors and variables can see their total output changing throughout the day to correspond with things like cloud cover & heavy rain, shading, daylight hours, the roof orientation, and the amount of sun rays that are currently reaching the panels.

During summer, a well-designed, fully functional solar array (one that’s either mounted on the roof or in a suitable location on the ground) may start generating useful electricity during the very early hours of the morning as soon as the sun comes up, and it will keep on producing energy for you in the evening. In other words, you are looking at solar generation in the UK starting from around 5 am until 9 pm during the summer months, depending on your exact location. 

In winter, the sun is much lower in the sky, and there are far fewer hours of sunlight during the day. For example, useful generation typically starts around 8.30 am, and it can stop generating useful amounts from around 3.30 pm. Again, it all depends on where you are in the UK.

Consider these time frames as examples rather than guaranteed windows that impact the total output of your solar panels.

What happens when the sun goes down?

The electricity produced by your panels will keep on decreasing as daylight fades, and your system’s inverter will continue to monitor the available power and operate within its designed limits. As soon as solar input has decreased to a point where the panels are ineffective because they can’t generate any more electricity, the inverter will no longer be able to convert solar energy for you, and it will automatically go into its night-time standby mode.

In other words, you won’t need to keep manually switching off the panels each day after the sun has gone down, or switching them back on again in the morning as soon as the sun comes out.

Another important thing worth taking into consideration during the planning of your solar installation project is how seasonal patterns in the UK can impact solar generation. As mentioned, a system that might not produce a great deal of electricity during the long, dark winter months might generate huge amounts during the summer months when the skies are clear and the days are filled with longer hours of natural sunlight.

You can get a far more realistic picture of how much you could save simply by looking at expected annual generation, along with how much and what time(s) of the day you will use the electricity.

You can power your home at night (and benefit from off-peak grid tariffs). Although solar panels are essentially ineffective when it’s dark outside, you don’t necessarily have to rely on buying electricity from the grid at peak rates.

Long after the sun has gone down, there are in fact two different ways you can get the most out of solar. One example is to store the electricity your panels produce during the day or charge a battery from the grid when electricity is cheaper.

Some of you may be asking: why not use battery storage to save daytime solar for when you’re at home in the evening? With home batteries, surplus electricity generated by your solar panels is stored so you can use it later, which means that instead of sending any excess electricity that you generated during the daytime to the grid, you keep some of it for use in the evening.

For instance, with the most common type of solar panel systems, around lunchtime is the sweet spot for generating your home’s main daily energy requirements. A solar battery can store the excess output during this time, and then discharge it later on in the evening to help power the appliances and devices in and around your home.

This popular solar solution for many UK homeowners is super handy, especially if you (and most other occupants in your home) are out during the day using little or no electricity, and find yourself at home more in the evening when you all use far more electricity.

If you decide against the battery option, then you can simply export some of the electricity generated while you are away and then purchase it back from the grid when you’re back home later.

By taking advantage of battery storage, though, you become far less reliant on the grid. They help you use the energy that your system has generated during the day.

However, the exact amount that you can save often boils down to several other factors, such as the total cost to install your system, battery size, tariff, how much electricity you generate, and how much you actually consume on an average basis.

Another important factor is the battery’s total capacity. For instance, on a sunny day during the summer without a cloud in sight, a small battery can fill quite quickly with charge, but if you simply don’t use enough electricity in the evening, then it won’t warrant investing in a larger solar battery. As mentioned, the ideal battery size for your project largely depends on your typical energy habits.

Can I charge my solar battery from the grid overnight?

Yes. These days, it’s possible to charge a growing number of home battery systems either from solar panels or from the electricity grid, which is handy if you have a ‘time-of-use’ tariff that offers cheaper electricity during certain periods.

With that said, tariff rates are rarely fixed for too long, so you might want to think about charging your battery at specific times of the day and then using the stored electricity during peak (more expensive) periods.

For example, some households use pricing options that can change every 30 minutes throughout the day, whereas others might use tariffs such as Octopus Go (a smart tariff with super cheap electricity between 00:30 – 05:30 every night – which is also compatible with all EVs and chargers).

The exact time when electricity is cheaper (i.e., the tariff rates) and the cost depends on current terms and conditions, so always remember to read the small print before signing up somewhere just because you heard there was a good deal. What might appear worthwhile at one particular time may not work out cheaper in the long run.

If you want to learn more about multi-rate tariffs like Economy 7 and how they can charge different rates at certain times of the day, check out the official Ofgem website, which explains in greater detail how it all works. Remember that although smart tariffs provide more flexible pricing solutions, the total financial benefit for you will depend on how you use electricity and things like whether your equipment can respond to the tariff.

Prior to going down this route, check that your tariff is suitable and that your battery and inverter support scheduled grid charging. It’s also worth taking into account battery losses and any other restrictions that may apply to your current energy agreement.

The aim of this pricing system is to use stored energy when the price increases, and to charge when electricity is cheaper. When used in conjunction with solar panel systems, it can significantly help UK homeowners make far more practical and efficient use of lower-cost grid electricity and their own generation.

Energy habits: when should I do laundry if I have solar panels?

Changing when and how you use your electricity can also make a huge difference, especially if you want to get the most out of your system or don’t have a large enough solar battery for your typical needs.

Solar panels tend to produce the most output at around lunchtime, although as the seasons change throughout the year, the exact best time for generation can vary somewhat. Other things that can also affect this are the weather, shading, roof pitch, and the direction that your roof and panels face.

Also, try to make the most of daytime generation. If your typical daily routine allows it, consider only using the most energy-hungry appliances (e.g., tumble dryers, conventional ovens, electric showers, and washing machines) between late morning and early lunchtime (so around 10 am and 2 pm, where possible).

Remember, instead of using these times as a guarantee of peak generation, consider them more a general guide. For example, these windows will likely differ on heavy cloud days during winter, or, for example, with an east- or west-facing roof.

Other things that you might like to try running during these hours instead of before or after include the following:

– Immersion heaters

– Portable heaters

– Dishwasher

– Gaming PC

– Kettle

– All other energy-hungry appliances that can safely operate during the day

If you have modern appliances with built-in smart controls and/or timers, use them. Figure out how you can schedule them to switch on and do their cycle when electricity prices are at their lowest or when your panels produce the most electricity, and try to do things like have a shower, dry your hair, play your favourite PC games, cook/prepare meals during the ‘sweet spot’ times.

What is self-consumption?

The term self-consumption in the context of energy, electricity, and solar power technology tends to refer to people who use the electricity that is generated by their own solar panels rather than relying on the grid for their electricity needs.

For example, if your solar panels generate electricity while using a conventional fan oven to cook a meal, that power can be used directly. If your appliances are switched off and your home doesn’t need a great deal of electricity, then instead, it’s possible to export more of that surplus solar generation.

The overall financial value of your solar system can significantly improve just by practising much better self-consumption techniques at home. It’s particularly relevant when the electricity that you pay for sets you back more than you actually receive for exporting your surplus energy to the grid.

Furthermore, a solar battery is another simple and effective way of increasing self-consumption because it allows you to save some of that surplus for later.

Quite possibly the best course of action for UK homeowners, depending on their current financial situation and circumstances, is to combine a well-designed system around sensible daytime energy habits, and to base your planning on your actual needs.

This approach doesn’t mean you can only run every appliance between 10 am and 12 pm every day because this is often impractical. It’s about becoming more flexible and thinking more about how, when, where, and why you use electrical devices and appliances the way you do.

Troubleshooting: Will a solar panel drain a battery at night?

No. A solar charging system that has been configured correctly is designed to ensure that current doesn’t flow backwards through the panels to cause the battery to drain throughout the night. Another way that the flow of electricity moves between the panels, battery and home can be better managed is with inverter systems and modern charge controllers.

The exact protection they offer typically depends on the type of system you have designed, but ordinary nighttime darkness is unlikely to cause your panels to discharge your solar battery. With that said, if you notice in the morning that your battery percentage/charge has dropped by a certain amount throughout the night, this can be put down to various reasons.

Why does my battery level fall overnight?

Don’t forget that your home continues to use electricity throughout the night, even when you’re not physically using any devices/appliances.

Fridge-freezers, for example, as well as home security systems, Wi-Fi routers, and various other devices left on standby, keep on consuming small amounts of power while you sleep unless they are completely unplugged from the wall. Therefore, if your battery sends power to these devices/appliances, it will gradually be depleted of charge.

Small amounts of energy are also used by the battery system and inverter themselves. Standby operation, controls, and its monitoring mode all require a small amount of power, too, but the exact power these devices use can also depend on the settings and the equipment.

The displayed charge level of battery management systems may also adjust, but the percentage shown on an app is simply an estimate of the battery’s current state of charge. As the system recalculates its available capacity, this value can change slightly.

You may also find that your settings will enable a scheduled discharge or allow for grid charging. Furthermore, its charging and discharging schedule may affect the level you see in the morning, especially if your system is configured around a time-of-use tariff.

If you notice a slight change (e.g., a drop) in the morning, it doesn’t mean that there is a fault. However, if your household uses only tiny amounts of electricity but you find that a large amount of charge has disappeared from your battery, the best thing to do is check the monitoring app, system documentation, and battery settings because there may be a fault.

If the same thing keeps happening and you can’t seem to get to the root of the problem, or you spot something out of the ordinary with your battery, let your installer know, and they should be able to help you fix the issue.