Choosing Solar & Battery Storage
Everything you need to know before you invest — from system sizing and costs to what questions to ask your installer.
Is solar right for me?
Solar PV works well for most properties, but a few factors determine how much you'll benefit. Understanding these upfront helps you set realistic expectations and size your system correctly.
South-facing roofs generate the most energy. South-west and south-east are also excellent. East/west-facing roofs still work well — you may just need a slightly larger system.
A pitch of 30–40° is ideal. Flat roofs can use angled mounting frames. Steep pitches above 50° reduce output slightly but are still viable.
Trees, chimneys and neighbouring buildings can reduce output significantly. A good installer will carry out a shading analysis before recommending a system.
Panels last 25+ years, so your roof should be in good condition before installation. If it needs work in the next 5–10 years, do it first.
The more electricity you use — and the more you can shift to daytime — the better your return. High consumers (heat pumps, EV chargers) benefit most.
Most domestic and commercial properties can export surplus energy back to the grid via the Smart Export Guarantee (SEG), earning a payment per kWh exported.
Even north-facing roofs can be viable for large commercial buildings with high daytime energy use. Don't rule it out without getting a proper assessment.
Getting the system size right
Oversizing wastes money. Undersizing leaves savings on the table. The right system size depends on your energy consumption, roof space and whether you're adding battery storage.
Rule of thumb: aim to self-consume as much of your solar generation as possible. If you're out during the day, a battery becomes essential to make the most of what you generate.
Be cautious of installers who recommend the maximum system your roof can fit without first analysing your actual energy consumption. Bigger isn't always better.
Do I need battery storage?
A battery stores surplus solar energy generated during the day so you can use it in the evening and overnight. For most households and businesses, adding storage significantly improves the economics of solar.
When does battery storage make most sense?
If you're away from home or the office during peak solar hours (10am–3pm), a battery captures energy you'd otherwise export at a low SEG rate and lets you use it when your tariff rate is higher.
What size battery do I need?
Most homes benefit from 5–10 kWh of storage. A 5 kWh battery covers a typical evening's usage; 10 kWh can take you through to the following morning. Larger commercial systems may need 20–100 kWh+.
Can I add a battery later?
Yes — most modern inverters are battery-ready. However, installing solar and battery together is usually more cost-effective than retrofitting later, as it avoids a second installation visit and potential additional equipment costs.
How long do batteries last?
Quality lithium batteries (such as Sunsynk, SolaX and Dyness) typically carry a 10-year warranty and are expected to last 15+ years with minimal degradation. Most guarantee at least 70–80% capacity retention over the warranty period.
Can a battery work during a power cut?
Not automatically — standard grid-tied systems shut down during outages for safety reasons. However, some batteries and inverters offer an "EPS" (Emergency Power Supply) or islanding mode that can power critical circuits during a blackout. Ask your installer about this if it's important to you.
Pair battery storage with an EV charger and you can charge your car overnight using solar energy stored during the day — dramatically reducing your motoring costs.
Costs, savings & returns
Solar is a long-term investment. Understanding the full picture — upfront cost, ongoing savings, export income and payback period — helps you make an informed decision.
Typical domestic system cost
A 4 kWp solar system with battery storage typically costs £8,000–£14,000 installed, depending on panel type, battery size and roof complexity. Prices vary — always get at least three quotes.
Annual savings
A typical household can save £600–£1,200 per year on electricity bills, depending on consumption, tariff and how much solar energy is self-consumed. Adding a battery increases self-consumption significantly.
Smart Export Guarantee (SEG)
You're paid for every unit of surplus electricity you export to the grid. Rates vary by supplier — typically 4–15p per kWh. Choosing a competitive SEG tariff adds meaningfully to your returns.
Payback period
Most domestic systems pay back in 6–10 years. Commercial systems with high daytime energy use often achieve payback in 4–7 years. After payback, the energy is essentially free for the remaining 15–20 years of system life.
VAT
Solar panels, battery storage and EV chargers are currently zero-rated for VAT when installed on domestic properties — a significant saving. Commercial installations are subject to standard VAT rates.
Finance options
Many installers offer 0% finance, green loans or power purchase agreements (PPAs). For commercial and agricultural customers, asset finance and leasing can make large systems cash-flow positive from day one.
Be wary of projected savings figures that assume 100% self-consumption or unrealistically high export rates. Ask your installer to show you the assumptions behind any payback calculation.
Choosing the right installer
The quality of your installation matters as much as the quality of the equipment. A poorly installed system can underperform, void warranties and create safety risks. Here's what to look for.
MCS Certification
MCS (Microgeneration Certification Scheme) is the industry standard for solar and battery installers. Only MCS-certified installations qualify for the Smart Export Guarantee. Always verify your installer's MCS number on the official register.
NAPIT or NICEIC registration
Electrical work must be carried out by a registered electrician. NAPIT and NICEIC are the main competent person schemes for electrical installation in the UK.
Experience and track record
Ask how many systems they've installed, how long they've been trading and whether they can provide references or case studies. A company that's been operating for several years is more likely to still be around to honour warranties.
Equipment brands
Reputable installers use panels and inverters from established manufacturers with strong UK warranty support. Ask about the brands they use and check the manufacturer's warranty terms independently.
Aftercare and monitoring
Find out what happens after installation. Do they offer system monitoring? What's the process if something goes wrong? A good installer will set up remote monitoring and be proactive about performance issues.
Detailed written quote
A professional quote should specify panel model and wattage, inverter brand and model, battery brand and capacity, estimated annual generation, projected savings and full installation costs. Avoid vague quotes.
Questions to ask your installer
A confident, reputable installer will welcome these questions. If they can't answer them clearly, that tells you something.
Common mistakes to avoid
✗ Choosing on price alone
The cheapest quote often means cheaper components, less experienced installers or corners cut on electrical work. Focus on value — the right system from a reputable installer will outperform a cheap one over its lifetime.
✗ Not checking MCS certification
Without an MCS-certified installation you cannot access the Smart Export Guarantee. Always verify certification before signing a contract.
✗ Ignoring shading
Even partial shading on one panel can significantly reduce the output of the whole string. Ask your installer how they're mitigating shading — optimisers or microinverters can help.
✗ Oversizing without battery storage
A large system without storage means exporting most of your generation at low SEG rates. Size the system to what you can self-consume, or add storage to capture the surplus.
✗ Not considering future energy needs
If you're planning to buy an EV, install a heat pump or extend your property, factor that into your system size now. It's much cheaper to install a larger system upfront than to add capacity later.
✗ Skipping the monitoring setup
Without monitoring you won't know if your system is underperforming. Most modern inverters include free monitoring apps — make sure your installer sets this up before they leave.
Ready to get a proper assessment?
Our team carries out free, no-obligation energy audits across Lancashire, Yorkshire, Cumbria and Greater Manchester. We'll size your system correctly, explain your options clearly and give you a detailed written quote.