FAQ – Solar Storage

All your FAQ questions answered on solar storage, see our other sections for other FAQs – Solar PanelsEV ChargingGeneral Queries.

Q: What is Solar Storage?

A: Fitting a battery storage system allows you to save the energy that is generated during the daytime and either wasted/not used or exported and store it until you are ready to use it. This increases the amount of usable solar energy utilised in the household from c.35% to c.70%. We can advise on a suitable options and leading brands to consider.


Q: How big a Solar Battery do I need?

This really depends on your household size and power usage, we can advise on a range of batteries to meet your needs. If you have solar panels already installed it’s possible to accurately measure your requirements. On average, households use around 10 kWh of electricity per day. If you have solar, some of that energy will come directly from the solar panels in the day. So around 7 kWh of storage would be enough to run your house all night. We recommend a bit of a buffer for a few rainy days as well as potential for the battery to degrade over time. A battery of 10 kWh of storage would be more than enough for most residential applications.


Q: Can a battery protect me from power cuts?

A: Yes, this is possible with certain brands e.g. Tesla. There are battery systems that can operate off grid in the event of a power cut, and then reconnect when the grid comes live again.


Q: How does a Solar Battery work?

A: A solar battery is a storage device for the excess electricity generated by your system, and a way for you to then use your own solar electricity at times when the sun isn’t shining. During the day there are moments when your panels are generating too much energy to be used within the property, and normally this excess electricity would be exported back to the grid. That changes with a battery system. Now, when you wouldn’t be using all your generated electricity this will go into the battery, stored ready to be used as soon you will need it. When the sun goes down, you will start to use the electricity in the battery instead of taking it from the grid.


Q: How can I benefit from Solar Battery Storage?

A: The main benefit is that you can store the excess electricity produced from your solar array during the day and use the electricity at night. Instead of exporting electricity back to the grid, you use it yourself, saving you the money if have had import grid electricity. So it reduces your energy bills. The other benefits to batteries are you helping the environment by importing less energy, more self-reliant and potentially can cope with power outages.


Q: Does the energy from my panels go first to the house or battery?

A: The appliances in the house will use the electricity first – any leftover will go to the battery. When the battery is full you export back to the grid in the usual way, or you can divert this power to heat the hot water or into electric vehicles.


Q: Can I use energy in the battery for the next day?

A: If you don’t use all the energy it will remain in the battery. However, because the battery is partially charged already, there will be less space in the battery to capture the next day’s solar energy. The best battery economics come when you are fully charging and discharging the battery every day, so that you are fully utilising the battery storage capacity you have paid for.


Q: Is it possible to use a Battery without Solar Panels charging it?

A: It is possible for batteries to simply charge from the grid using off-peak cheap electricity. We can advise on compatible batteries from Sonnen and Tesla.


Q: What is the payback, when will an investment in a Solar Battery pay for itself?

A: This is not a straightforward calculation as it depends on how the household uses the battery, and if it is possible to fully utilise the battery capacity on a daily basis. The payback of a well-sized battery system is similar to the lifetime of the battery unit itself (10 -15 years). It means you are more independent of the grid and able to use more of your own generated energy, but the return on investment is not as clear cut as with solar panels.


Q: What is the lifetime of a battery?

A: Most batteries have a 10-year warranty. This type of residential solar battery technology is relatively new to the market and so there is little evidence of what will happen after 10 years. Although the batteries could last 20 years or longer we recommend budgeting for a replacement after the 10 year warranty is up. Sonnen are an established German manufacturer with a 10 year warranty but an expected lifespan of up to 20 years.


Q: Can the battery be installed anywhere?

A: It is possible to install both outdoors and indoors, but these units are quite sizeable and the decision where to locate them needs careful thought. We can advise on what is suitable for your individual property.

Q: Are batteries safe and fireproof?

A: Yes, all batteries meet stringent fire safety regulations, and can be used indoors.


Q: Can I compare the different batteries on the market?

A: Please see the table below with a summary of the differences:











ProductUsable Capacity (kWh)Charge Rate (kW)Outdoor RatedBackup Function IncludedInstallation Guide Price(ex VAT) May 2020WarrantyChemistryAC / DC Coupled
Enphase2.4 - 6.0 kWh1NN£3608 - £740010yrs or 3650 full cyclesLiFePO4AC
LG Chem Resu 7H/10H6.6 / 9.3 kWh3.5 - 5.0NN£5600 - £620010yrs or 19.6 / 27.4 MWhLiFePO4DC
Sonnen 9.435 - 15 kWh3.3NN£5300 - £880010000 cyclesLiFePO4AC
Tesla13.5 kWh3.68 / 5.0YY£7550 - £830010yrs (unlimited) cyclesLiNiCd

Q: Is your work covered by any warranty? 

A: Our workmanship is guaranteed for a period of 2 years during which time we will respond to any problems at no cost to yourself. As members of the Real Assurance consumer protection scheme (RECC) customers are also protected by an insurance backed warranty scheme.


Q: Why should I choose SogoSolar?

We have 10 years of experience in fitting solar storage systems, we will listen to your requirements and design a system that suits your lifestyle and budget. We have access to all the leading brands and can ensure an honest, transparent approach which includes monitoring system performance for two years from installation. We are always pleased to let you speak to previous customers.