Solar Battery Backup For Home Power Outages

solar panel battery backup

A home battery backup system provides electricity to households during power outages by storing energy from solar panels or the grid. These systems are becoming increasingly vital for UK homes to cope with potential blackouts and provide resilience against extreme weather events.

Having a reliable backup power source is crucial for running essential appliances and medical devices, maintaining a comfortable temperature, and avoiding food spoilage when the grid fails. For vulnerable people relying on electrically-powered healthcare equipment, backup systems can be lifesavers during outages.

This comprehensive guide will cover everything related to installing and using a home battery backup system tailored for UK households.

Key Takeaways

    • Solar battery systems can store energy from the sun and the grid to power your home during outages, keeping essential appliances like fridges and Wi-Fi running smoothly.
    • Solar batteries that can provide back-up power have a relay (a transfer switch) which will automatically disconnect your electricity supply from the grid when it detects a power cut.

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Understanding Solar Battery Backup Systems

Solar battery backup systems kick in when the power goes out, keeping your lights on and fridge cold. They can harness energy from the sun and be charged by the gird, storing it for any day the grid lets you down.

How does a solar backup battery system work?

A solar backup battery system works by storing surplus energy generated by solar panels during the daytime and utilising that stored energy to power critical home loads when the grid power goes out.

EPS, or Emergency / Backup Power Supply, refers to a solar system’s ability to automatically switch over to battery backup in case of a grid outage. Despite many solar inverter spec sheets listing EPS capability, most grid-tied solar PV systems are required by law to disconnect from the grid during failures to protect utility workers. Special EPS inverters with transfer switches are needed for true backup functionality.

When sized properly, an EPS solar system can power a home’s essential circuits from battery reserves when grid power is interrupted. Lights, fridge, freezer, internet, and other critical loads stay on uninterrupted. EPS requires careful design and safety considerations, along with battery storage, but delivers invaluable resilience.

The key components that enable the system to work this way are:

1. Solar Panels:
Photovoltaic solar panels generate clean electricity from sunlight during daytime hours. They feed power to both the home’s electric loads as well as charge the battery bank.

2. Battery Bank:
An appropriately sized battery bank stores excess solar energy for later use. Quality lithium-ion batteries provide resilient performance for thousands of cycles. The batteries sit idle while grid power is on, then activate to power the home when an outage occurs.

3. Inverter and Transfer Switch:
A specialised inverter converts the battery’s DC power into usable AC electricity for the home’s circuits. It works together with an automatic transfer switch that seamlessly transitions the home from grid to battery power when it senses the outage.

4. Backup Circuits:
Dedicated backup loads allow the battery system to efficiently power only the most critical appliances and devices. This avoids overtaxing the system. Backup circuits keep lights, fridge, freezer and other essentials running.

By bringing these elements together into an integrated system, UK homeowners can utilise their solar investment to ride through grid power cuts in safety and comfort. The solar battery backup system serves as an on-site microgrid, keeping the most important home functions operating even when the wider grid fails.

Will solar panels continue to charge the battery during a power cut?

Solar panels unfortunately cannot directly charge batteries when the grid goes down in a typical grid-tied solar system. This is due to safety regulations that require grid-tied solar inverters to shut off when the utility grid fails. This prevents exporting electricity during an outage, which could endanger utility repair crews.

So in a blackout scenario, even though the sun may be shining, the solar panels themselves will stop functioning without the grid to connect to. This safety shutdown prevents the PV system from charging its batteries.

To work around this issue and keep solar panels charging batteries during a power cut, an EPS solar setup (backup gateway) is required. An EPS inverter with transfer relay switches that can disconnect the solar system from the grid in an outage. It then creates a mini-grid within the home, with the panels charging batteries directly. The batteries then power emergency backup loads to maintain critical appliances like lights, fridge, freezer and internet through the outage.

So with special EPS inverter technology, solar panels can continue charging batteries to sustain essential home loads, despite the grid going down and cutting the panels off directly. This setup allows much greater home resilience whenever utility outages occur.

Key Factors to Consider for Solar Battery Backup Systems

Battery Storage Capacity

Think about what you need during a blackout—perhaps keeping lights on, powering essential devices or maintaining climate control. A typical solar battery backup systems can offer between 10 kWh to 30 kWh of storage (e.g. Tesla Powerwall 13.5 kWh); this detail helps determine how long your home can stay powered during an outage.

Knowing your daily kilowatt-hour (kWh) consumption guides you in selecting the right capacity. For instance, if your house typically uses around 10 kWh per day and you’re aiming for three days of backup power without grid electricity, aim for a system with at least 30 kWh storage capability.

It’s all about finding a balance between necessity and budget while ensuring your backup setup matches or surpasses this demand to keep critical appliances running smoothly during power cuts. Prioritise backing up the fridge, freezer, lights, heating, medical devices, etc. Size the system to supply enough power for these essentials.

Power Requirements

Determining your home’s backup power requirements is crucial for properly sizing the inverter which supplies power using the energy stored in the battery. Here are the key steps:

  1. Catalogue Critical Loads
    Make a list of all the essential appliances and devices that need to stay powered on during an outage. Typical critical loads are lighting, fridge, freezer, heating system, WiFi router, medical devices, and others vital to daily life.
  2. Measure Load Wattages
    Check appliance labels to record the wattage of each identified critical load. Sum the wattages to calculate your total backup power needs.
  3. Account for Peak Demand
    Appliances like fridges cycle on and off, creating short periods of higher wattage draw. Size the system for these peak demand spikes to prevent overload.
  4. Add Buffer Margin
    It’s smart to add an extra 20-30% buffer margin on top of the calculated critical load and peak demand totals. This helps ensure adequate power to account for other small loads being added over time.

A typical solar battery system with backup ESP can provide a power output ranging from 5 to 7 kW. It is essential to make sure your power draw won’t exceed the maximal power supply that the battery system can deliver.

Features and Benefits of Top Solar Battery Backup Systems

The two leading solar battery backup options for UK homes are the Tesla Powerwall 2 (the champion) and GivEnergy All-In-One Battery (the challenger). Here’s a comparison of their key features and benefits:

SpecificationTesla Powerwall 2GivEnergy All-In-One
Capacity13.5 kWh13.5 kWh
Power Output7 kW peak / 5 kW continuous7.2 kW peak / 6 kW continuous
Warranty10 years12 years
ScalabilityMax. 10 batteriesMax. 6 batteries
Monitoring and ControlSmartphone appSmartphone app
DesignModern, wall-mountedAll-in-one floor cabinet
Price including installation£7,900 – £10,000£6,900 – £9,300

Tesla Powerwall 2 Benefits

  • High quality Tesla lithium-ion battery cells
  • Sleek modern aesthetic for indoor/outdoor installation
  • Monitored and controlled from the market-leading Tesla smartphone app
  • Scalable capacity by adding up to 10 additional Powerwalls

GivEnergy All-In-One Benefits:

  • Higher continuous and peak power output
  • Lower installation price
  • Longer warranty
  • Better availability

The Worth of a Solar Battery Backup System

A solar battery backup system brings peace of mind during power outages. It ensures your home stays powered when the grid goes down. However, additional external components and extra work are required to enable the backup EPS function to supply power to your critical circuits.

This may involve installation of a new external earth rod and a backup distribution board to link out the circuits. This is a time-consuming addition to any solar panel and battery installation job, hence the higher cost of installing such systems. When considering adding a battery backup system consider how often will you be using the function, and whether or not backup storage is essential to your routine activities.

Remember you can get in touch with Cambridge Renewables and we’ll design a bespoke solution to match your backup energy requirements. Contact us today at 01638 750 660 for expert guidance and assistance.

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We will use the provided information to suggest a home battery system that aligns with your energy needs. Our team will contact you to discuss the system’s design and installation costs. Should you decide to move forward with our proposal, we’ll arrange for an on-site survey to assess your current electrical setup.

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