Countryside Village, Powercut with lights on

Will Solar Panels Work During a Power Cut?

No, solar panels typically do not work during a power cut or blackout unless they are combined with a battery storage system. This is a safety measure to prevent the solar panels from sending electricity back to the grid and potentially harming workers repairing the power lines.

When the electricity grid goes down, the solar panel inverter automatically detects and shuts off to disconnect from the national grid. This is because there is a real risk of electrocution for any engineers who may be working on the grid nearby if solar panels are still generating and sending electricity to the lines. That risk is especially high if there are lots of solar panel systems in the affected neighbourhood.

However, if you have a battery storage system with back up capabilities installed along with your solar panels, the batteries can store the energy generated during the day. Then, during a power cut, that stored energy in the batteries could be used to power your home and essential appliances, such as microwaves or kettles, until grid power is restored – if your system is configured to handle backup capabilities.

Without battery storage, grid-tied solar panels alone cannot provide power during an outage. However, with a properly configured battery backup system, your solar panels can continue generating electricity that is stored in the batteries to keep your home powered through a power cut.

How to Make Solar Panels Work During a Power Outage

It is possible for solar panels to work during a power outage, but it requires a specific setup and is not the default behaviour. Solar panels will only work during an outage if:

  1. Your panels are not grid-tied. This means you live off-grid in a remote location not connected to the national electricity grid. In this case, your home can continue drawing power from solar panels or other off-grid sources like wind turbines or hydroelectric generators.
  2. You have a solar battery installed with backup power functionality. Most modern solar PV systems come with a battery to store excess solar power. If configured properly, this battery can provide backup power to your home’s circuits during a grid outage using the stored solar energy.

So, in summary, basic grid-tied solar panels will shut off for safety reasons during a power cut unless you have a battery backup system or live completely off-grid. However, with the system configuration, you can use your solar panels to keep your home powered during periods of grid blackouts.

Will Adding Battery Storage Solar Panels Power a Home During a Power Cut?

While adding battery storage to a solar PV system is a step in the right direction for backup power, it does not automatically enable the batteries to power your home during a grid outage. Many standard solar batteries lack the Emergency Power Supply (EPS) or “islanding” functionality required to safely disconnect from the grid and supply the home’s circuits.

 

Jason Howlet and GivEnergy Inverter

Jason Howlett, GivEnergy Group CEO

Jason Howlett, CEO of GivEnergy, comments:

‘One of the more common misconceptions about solar panels we see here at GivEnergy is that a solar PV array will make you energy independent. While the benefits of having solar generation should never be underplayed, solar panels are only effective when installed as a standalone measure.

For instance, your solar panels won’t protect you from a power cut by themselves. Being able to generate energy is not the same as being able to store and automatically switch over to that energy during an outage.

When having the system wired in, you can request one of two routes to backup power in the event of a power cut:

  • Essential loads (providing power to essentials only, such as a fridge, lights, Wi-Fi router, etc)
  • Crossover switch (providing power to the whole home via an automatic switchover)

More premium battery storage systems, meanwhile, may offer backup power out of the box. (I.e, without needing extra wiring work.) Always consult with your solar installer to discuss your backup power objectives.’

How Common are Power Cuts in the UK?

In the UK, an outage may be more common than you think. A study found that nearly 66% of households will experience a power cut, which usually lasts an estimated two and a half hours. Due to the way the grid is designed, a power cut may not affect all houses on the same street as this is typically down to different suppliers. If you have solar panels on your property and are experiencing outage you can visit the National Grid Power Outage microsite to determine if your area is currently impacted.*

During the day, a properly sized solar PV and battery system can keep a home powered during a power cut if sufficient sunlight hits the panels. The solar panels will continue generating electricity that can directly power the home’s essential loads while recharging the batteries for night use.

How Long Can a Solar PV System Power My House During a Power Outage?

Depending on your typical usage, a typical 10 kWh battery storage capacity, and modest energy usage, most homes can run off the batteries alone for 12-24 hours** without solar charging.

Careful load management and prioritising essential energy can extend this further. However, heavy-use appliances such as ovens, kettles, and vacuum cleaners would significantly decrease the time you can run on battery storage only without further energy top-ups from either solar panels or grid connection.

For example, if the home uses 1 kW per hour on average for essential loads like lights, fridge and internet, then a 10 kWh battery theoretically provides 10 hours of backup power at night during a power cut:

10 kWh / 1 kW = 10 hours of backup power.

How Will the Length of a Power Cut Affect the Performance of Solar Panels?

The duration of a power cut can significantly impact the performance and effectiveness of solar panels and a battery system in providing backup power to a home. Here are the key considerations:

Short Power Cuts (Hours)

Many power outages in the UK last up to 24 hours, and a properly sized solar and battery system can typically keep a home powered, especially if the outage occurs during daytime hours when sunlight is available.

  • During the day, the solar panels continue generating electricity to directly power the home’s loads and recharge the batteries.
  • At night, the home runs off the stored energy in the batteries until the grid is restored or the sun rises again.

 Longer Power Cuts (Over 24 Hours)

For prolonged outages lasting several days or more, the duration that the solar panel and battery system can sustain a home depends on battery capacity, solar exposure, and managed energy consumption.

  • With good solar exposure during daytime hours, the panels can recharge the batteries daily to enable backup power.
  • Consecutive cloudy days with limited solar charging may drain batteries faster than they can recharge.
  • Prioritising essential loads and practising energy conservation becomes crucial to maximising battery runtime.

Winter Solar Panel Performance

The season and weather conditions can also affect solar charging ability during an extended outage:

  • Winter months with shorter days and lower sun exposure may limit solar charging capability.
  • Snow or overcast conditions further reduce the panels’ ability to recharge batteries sufficiently each day.

This can quickly deplete battery reserves if the outage is prolonged without sufficient solar exposure to recharge.

Tip: Keeping Solar Batteries Topped Up in Winter Months

Using a low-rate tariff can be an effective way to ensure your solar batteries stay topped up with electricity, even during periods of low sunshine or night-time power outages. This provides backup energy security through outages while minimising your energy bills.

*https://powercuts.nationalgrid.co.uk/

** https://www.solar.com/learn/how-long-can-a-battery-provide-power-during-an-outage/