Solar Panels, Battery Storage and Solar Water Heating: Costs, Payback and New Technology

Solar Panels, Battery Storage and Solar Water Heating

A practical guide to solar panels, battery storage, solar roof tiles, solar fencing and solar water heating, including costs, payback, long-term savings, installation, planning and new technology.

Solar energy is becoming one of the most important home upgrades in the modern world. It is no longer just a few panels fixed to a roof as an eco-extra. Homeowners can now consider roof-mounted solar panels, in-roof panels, solar roof tiles, battery storage, smart export tariffs, solar hot water systems, solar diverters, EV charging links and even newer products such as solar fencing and plug-in solar panels.

For many homes, solar is no longer only about being green. It is about long-term cost control.

Electricity prices remain high, households are using more power, and homeowners are increasingly looking for ways to reduce dependence on the grid. A well-designed solar system can generate electricity for decades, reduce bills, support battery storage and improve the long-term running cost of the home.

However, solar needs proper design. The best system depends on roof orientation, shading, household electricity use, battery size, hot water demand, roof condition, planning restrictions, installation quality and how much energy the household can use during the day.

Quick Answer

Solar panels convert sunlight into electricity for use in the home. Battery storage allows excess solar electricity to be stored and used later, instead of exporting it all to the grid. Solar water heating uses roof-mounted collectors to heat domestic hot water, usually through a dedicated or compatible hot water cylinder.

Solar PV is usually the best option for generating electricity. Battery storage can improve the value of that electricity by allowing more of it to be used in the home. Solar water heating can be very effective for homes with strong hot water demand, especially larger family homes with hot water cylinders.

A typical solar panel system can last 25 to 30 years or longer, with output gradually reducing over time. Some solar roof tile products are designed for longer service lives and can be especially interesting where the roof is already being replaced.

For the best result, homeowners should compare the system cost, expected generation, self-consumption, export tariff, battery use, roof condition, hot water demand and installation quality before deciding what to install.

Why should homeowners consider solar now?

Solar is worth considering because it can reduce long-term energy costs and make the home less exposed to future electricity price increases.

The basic idea is simple. Every unit of electricity generated and used in the home is a unit that does not need to be bought from the grid. If the system produces more electricity than the household can use at that moment, the excess can either be exported to the grid or stored in a battery for later.

Solar can be especially useful for homes where people are in during the day, where appliances can run during daylight hours, where a battery is installed, or where the property has an electric vehicle, heat pump, immersion diverter or high daytime electricity use.

Solar may be suitable for:

family homes;
larger houses;
homes with south, east or west-facing roof slopes;
homes with good roof space;
extensions and refurbishments;
homes with electric vehicles;
homes with daytime electricity use;
households wanting battery storage;
homeowners replacing or renovating a roof;
homes with high hot water demand;
homeowners wanting better long-term energy control.

Solar is not just about the panels. The value comes from the system design.

A cheap system in the wrong position, with poor inverter choice, no thought about battery storage and little daytime use, may not perform as well financially as a properly designed system that matches the household’s real energy use.

Solar PV panels

Solar PV panels generate electricity from sunlight. They work best on an unshaded south-facing roof, but east and west-facing roofs can still work well, especially where the household uses energy in the morning or afternoon.

Solar PV can help power:

lighting;
appliances;
washing machines;
dishwashers;
tumble dryers;
cooking equipment;
home office equipment;
heat pumps;
EV chargers;
immersion diverters;
general household electricity demand.

A typical domestic system might be around 3.5kWp to 5kWp, depending on roof space and household needs. Larger homes may consider larger systems where roof space, budget and grid connection allow.

Battery storage

Battery storage allows unused solar electricity to be stored and used later.

Without a battery, much of the solar electricity generated during the day may be exported if the household is not using enough power at that time. With a battery, more of the generated electricity can be used in the evening, overnight or during peak-price periods.

Battery storage can be useful where:

the household is out during the day;
electricity use is higher in the evening;
the home has smart tariffs;
the homeowner wants more energy independence;
the home has an electric vehicle;
the system produces more electricity than is used immediately.

Battery storage adds cost, so the payback needs to be checked. It can improve the financial case, but only where the battery is sized and used sensibly.

Solar water heating

Solar water heating, also called solar thermal, uses collectors to heat domestic hot water.

This is different from solar PV. Solar PV produces electricity. Solar thermal produces hot water.

Solar water heating can be especially interesting for larger homes with strong hot water demand. A couple of well-positioned solar thermal panels can provide a large share of a home’s hot water in the warmer months and reduce the amount of gas, electricity or other fuel used to heat water.

In summer, solar thermal can often provide most or nearly all of the hot water needed. Across the whole year, the usual expectation is more modest, because winter solar input is lower. The main boiler, immersion heater or heat pump will still be needed for backup.

For homes with a conventional hot water cylinder, solar thermal can be a very practical option. For homes with a combi boiler and no cylinder, it may be more complicated because solar thermal usually needs a compatible cylinder arrangement.

TOP TIP

Do not look at solar panels, batteries and solar water heating as separate gadgets. The best result usually comes from designing the whole energy system around how the household actually uses electricity and hot water.

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What new solar technology should homeowners know about?

Solar technology has moved on quickly. Homeowners now have more choices than traditional roof-mounted panels.

In-roof solar panels

In-roof solar panels sit more flush with the roof covering than standard panels. Instead of being mounted above the roof tiles on rails, they are integrated into the roof plane.

They can look cleaner than standard panels and may be worth considering where the roof is being replaced, an extension roof is being built or appearance matters.

However, they need proper waterproofing, ventilation, flashing and installation detailing. They are often easier to justify when roof works are already planned.

Solar roof tiles

Solar roof tiles, sometimes called solar slates or solar shingles, are designed to replace normal roof tiles while generating electricity.

They can look much more subtle than standard solar panels, because the solar technology forms part of the roof covering. This can be attractive for design-led homes, new builds, roof replacements and properties where the homeowner dislikes the look of standard panels.

Solar roof tiles may be worth considering where:

the roof is already being retiled;
the homeowner wants a much cleaner appearance;
the property has a sensitive frontage;
a new build or major roof refurbishment is planned;
appearance is more important than the lowest payback cost.

However, standard solar panels are usually more cost-effective where the existing roof is in good condition. Solar roof tiles often cost more and are usually most sensible when the roof covering is being replaced anyway.

Solar fencing and vertical solar panels

Newer products such as solar fencing and vertical solar panels are starting to appear. These can be useful where roof space is limited, the roof is shaded, or there is a suitable boundary, garden structure or external area that can generate electricity.

Solar fencing is unlikely to replace a well-positioned roof system for most homes, but it shows where the market is heading. Solar may increasingly become part of building materials, fencing, garden structures, carports, outbuildings and external design.

As with any new product, homeowners should check:

proven performance;
product warranty;
installer experience;
electrical compliance;
weather resistance;
maintenance;
planning restrictions;
whether the product is approved for export tariff purposes.

Solar diverters

A solar diverter sends excess solar electricity to an immersion heater to heat water instead of exporting it to the grid.

This can be useful where the home has a hot water cylinder and excess daytime generation. It may be a lower-cost way to use more of the electricity generated by solar panels.

A diverter is not the same as solar thermal. Solar PV plus a diverter uses electricity to heat water. Solar thermal directly captures heat from the sun to heat water.

EV charging and solar

Solar can work well with electric vehicle charging where the car is at home during the day.

A smart EV charger can sometimes use surplus solar electricity to charge the car. This can improve the value of the solar system, but it depends heavily on when the car is parked at home and how much spare solar electricity is available.

Smart tariffs and export payments

Homeowners may be able to export unused electricity to the grid through a suitable export tariff. Rates vary between suppliers, and the best option can change over time.

Some homeowners may also use smart tariffs to charge a battery when electricity is cheaper and use stored energy when electricity is more expensive. This is more advanced and depends on the tariff, battery, inverter and control setup.

The key point is that solar payback is no longer only about the panels. It is about how the household uses, stores and sells the energy.

How do the costs and payback work?

Solar costs and payback vary because every home is different. The roof size, orientation, shading, battery size, electricity usage, export tariff and installation cost all affect the return.

The figures below are illustrative examples based on typical UK assumptions and current-style energy pricing. They should be checked against live tariffs and actual installer quotes before a homeowner makes a decision.

Example 1: Solar PV without a battery

Assume:

3.5kWp to 4kWp solar PV system;
installation cost around £6,100;
annual generation around 3,400 to 3,800kWh;
example calculation based on 3,600kWh per year;
45% used in the home;
55% exported;
electricity import value around 24.67p per kWh;
example export value around 15p per kWh.

Illustrative annual value:

1,620kWh used in the home x 24.67p = about £400;
1,980kWh exported x 15p = about £297;
total annual value = about £697.

Illustrative payback:

£6,100 system cost ÷ £697 annual value = about 8.7 years.

This is a simplified example. The real payback could be shorter or longer depending on location, roof orientation, shading, export tariff and how much electricity the household uses during the day.

Example 2: Solar PV with a battery

Assume:

solar PV with battery;
installed cost around £9,800;
annual generation around 3,600kWh;
75% used in the home because the battery stores more daytime generation;
25% exported;
electricity import value around 24.67p per kWh;
example export value around 15p per kWh.

Illustrative annual value:

2,700kWh used in the home x 24.67p = about £666;
900kWh exported x 15p = about £135;
total annual value = about £801.

Illustrative payback:

£9,800 system cost ÷ £801 annual value = about 12.2 years.

This does not mean batteries are a bad idea. It means the battery needs to be judged properly. A battery may provide more value where electricity prices are high, evening use is heavy, export rates are low, smart tariffs are used or the household wants more resilience.

Example 3: Solar water heating for a larger home

Solar thermal can be very interesting for larger homes with regular hot water demand.

Assume:

solar water heating installation cost around £6,000;
a larger home uses around 3,500 to 4,500kWh of useful hot water energy per year;
gas-heated hot water using a boiler;
gas unit rate around 5.74p per kWh;
boiler efficiency around 90%;
solar thermal provides around 50% of annual hot water demand.

For a 4,500kWh useful hot water demand:

gas input needed at 90% boiler efficiency = about 5,000kWh;
5,000kWh x 5.74p = about £287 per year;
50% solar contribution = about £143 annual saving.

At that saving level, simple payback against a £6,000 installation is long. However, the picture changes if:

gas prices rise;
the property uses electricity for water heating;
hot water demand is high;
the system is fitted as part of wider roof or cylinder works;
the homeowner values long-term energy resilience;
the system provides most hot water for much of spring, summer and early autumn.

If hot water is currently heated by electricity at around 24.67p per kWh, the same 4,500kWh hot water demand would cost about £1,110 per year before solar contribution. A 50% solar contribution could be worth around £555 per year. That gives a much stronger payback case.

This is why solar thermal can look modest on gas savings but much more attractive where electricity is being used for hot water, or where a larger home has heavy hot water use.

Solar water heating and the “free hot water” idea

Solar thermal can provide a very large share of hot water in the warmer months.

In a well-designed system, a larger family home may receive most of its hot water from solar thermal through spring, summer and early autumn. In some homes, that can feel close to “free hot water” for much of the year after installation cost.

However, it should not be sold as guaranteed free hot water for 9 or 10 months in every property. Winter performance is lower, weather varies, and the household still needs a backup heat source.

The honest position is:

Solar thermal can provide nearly all hot water in summer and around half of annual hot water needs in a typical setup, with better results where the system is well sized and the household has strong hot water demand.

IMPORTANT POINT

Solar payback should be calculated from actual household use, not brochure figures. Roof orientation, shading, daytime electricity use, battery size, export tariff, hot water demand and installation cost all change the result. A system that works brilliantly for one house may not be the best investment for another.

How long do solar panels last?

Solar panels are long-life products.

Many solar panels are sold with performance warranties of around 25 years, but that does not mean they stop working at 25 years. Panels usually continue generating beyond the warranty period, with output gradually reducing over time.

A well-installed system can continue to generate useful electricity for 30 years or more. Some solar roof tile products are designed for long service lives and may be offered with long product or waterproofing warranties.

The long-term value of solar is one of the strongest arguments for installing it.

Even if the payback period is 9 to 13 years, the system may continue producing electricity for many years after that. Once the installation has paid for itself, the ongoing generation can provide a long period of reduced energy costs.

Degradation

Solar panels slowly lose output over time. This is known as degradation.

A typical panel might still produce a high percentage of its original output after 25 years, depending on the product, installation quality and maintenance. Better panels may degrade more slowly.

For homeowners, the important point is that solar is not usually a short-term product. It should be viewed as a long-term asset.

Inverters and batteries may not last as long as panels

The panels may last for decades, but other parts of the system may need replacement earlier.

Inverters and batteries typically have shorter lifespans than the panels themselves. This should be allowed for in the long-term financial calculation.

Homeowners should ask about:

panel warranty;
inverter warranty;
battery warranty;
workmanship warranty;
monitoring;
maintenance;
replacement costs;
whether the installer will still support the system.

What installation and planning issues should homeowners check?

Solar installation is not just an electrical job. It affects the roof, structure, appearance, wiring, inverter location, battery location, meter setup and sometimes planning.

Roof condition

Before fitting solar panels, the roof should be in good condition.

If the roof covering is near the end of its life, it may make sense to repair, retile or replace the roof before installing panels. Removing panels later to carry out roof repairs can be expensive and inconvenient.

This is where solar roof tiles or in-roof panels can become more attractive. If the roof is already being replaced, the homeowner can consider whether to integrate solar into the roof covering rather than mounting standard panels on top.

Orientation and shading

Solar panels work best where they receive good sunlight.

A south-facing roof usually gives the best output, but east and west-facing roofs can still perform well. East-facing panels can help morning use. West-facing panels can help late afternoon and early evening use.

Shading from trees, chimneys, dormers, neighbouring buildings or roof features can reduce performance. The installer should check shading properly before designing the system.

Structural loading

Solar panels, rails, roof tiles, wind loading and fixings all affect the roof.

Most roofs can accommodate solar panels, but the installer should still check suitability. Older roofs, fragile tiles, flat roofs, large arrays and unusual structures may need extra care.

Inverter and battery location

The inverter converts the DC electricity generated by the panels into AC electricity for the home.

The inverter and battery should be positioned carefully. Consider:

ventilation;
access for maintenance;
cable routes;
noise;
fire safety;
weather protection;
appearance;
proximity to consumer unit;
garage, utility room or plant space options.

A battery should not be squeezed into an unsuitable space just because it is convenient.

Cabling and appearance

Solar cabling should be planned neatly.

External cable runs, conduit, inverter routes and meter connections can look untidy if not planned properly. Where possible, cables should be concealed, routed discreetly or coordinated with other works.

If solar is being installed during an extension, rewire or roof project, there may be a better chance to hide cable routes cleanly within the building fabric.

Planning permission

Many domestic roof-mounted solar panel installations are permitted development, provided they meet the required limits and conditions.

However, planning checks are important where:

the property is listed;
the property is in a conservation area;
the home is in a national park or protected landscape;
panels would be on a prominent elevation;
a flat roof system is proposed;
a ground-mounted array is proposed;
the property is a flat or maisonette;
permitted development rights have been removed;
solar roof tiles or unusual products affect appearance.

Listed buildings and conservation-sensitive properties need particular care.

MCS certification and export tariffs

Homeowners who want to receive export payments usually need an installation and installer certified through MCS or an equivalent recognised scheme.

A smart meter that records exported electricity may also be needed.

Before placing an order, homeowners should check:

whether the installer is MCS-certified;
whether the products are MCS-certified;
whether the system can qualify for export payments;
whether a smart meter is required;
whether the distribution network operator needs notification or approval;
what paperwork will be provided after installation.

Solar Panels, Batteries and Solar Heating Planning Checklist

Before installing solar panels, battery storage or solar water heating, think about:

whether the roof faces south, east or west;
whether the roof is shaded;
whether the roof covering is in good condition;
whether a roof replacement is planned;
whether standard panels, in-roof panels or solar roof tiles make most sense;
whether solar fencing or garden-mounted solar could help where roof space is limited;
how much electricity the household uses during the day;
whether a battery would improve self-consumption;
whether an EV charger will be linked to the system;
whether a solar diverter could heat water;
whether solar thermal would suit the hot water demand;
whether the home has a suitable hot water cylinder;
whether the installer is MCS-certified;
whether export tariff eligibility is important;
whether planning permission or listed building consent needs checking;
where the inverter and battery will be located;
how cables will be routed;
whether scaffolding is included in the quote;
what warranties are offered;
whether monitoring is included;
how long the payback is likely to be;
whether the calculations use realistic energy prices and usage.

Frequently Asked Questions About Solar Panels and Batteries

Are solar panels worth it in the UK?

Solar panels can be worth it in the UK, especially where the roof is suitable, the household uses electricity during the day, the installation cost is sensible and export or battery storage is used well. The payback depends on the property and energy use.

Do solar panels work on cloudy days?

Yes. Solar panels still generate electricity on cloudy days, although they produce more when sunlight is stronger.

Is a battery worth adding to solar panels?

A battery can be worth adding where it allows more solar electricity to be used in the home instead of exported. It is most useful where daytime use is low but evening electricity use is high.

Are solar roof tiles worth it?

Solar roof tiles can be worth considering where the roof is already being replaced or where appearance is very important. Standard solar panels are usually more cost-effective on an existing roof.

Can solar panels last 40 years?

Some systems may continue producing useful electricity for 40 years, but performance will reduce gradually over time and parts such as inverters or batteries may need replacement earlier. A 25 to 30-year performance view is usually more cautious.

What is solar thermal?

Solar thermal uses roof-mounted collectors to heat domestic hot water. It is different from solar PV, which generates electricity.

Can solar thermal provide free hot water?

Solar thermal can provide most or nearly all hot water in summer and a meaningful share across the year. However, backup heating is still needed, especially in winter.

Is solar thermal better than solar PV?

Solar thermal can be very good for hot water, especially in homes with strong hot water demand. Solar PV is more flexible because it generates electricity that can power appliances, charge batteries, run heat pumps or support EV charging.

Can I use solar panels to heat my hot water?

Yes. Solar PV can heat water through an immersion diverter if the home has a hot water cylinder. Solar thermal can heat hot water directly through solar collectors and a compatible cylinder.

Do solar panels need planning permission?

Many domestic solar panel installations are permitted development, but there are exceptions. Listed buildings, conservation areas, flats, protected areas, ground-mounted systems and unusual designs should be checked before work starts.

Do I need an MCS installer?

If you want access to export payments, an MCS-certified or equivalent certified installation is usually important. It also helps provide confidence that the system meets recognised standards.

Should I install solar before replacing my roof?

If the roof is old or due for replacement, it is usually worth dealing with the roof first. Otherwise, panels may need to be removed later for roof repairs.

What is the biggest mistake homeowners make with solar?

The biggest mistake is judging solar only by panel cost. The real value depends on system design, roof condition, energy use, export tariff, battery sizing, hot water demand and installation quality.

Planning Solar Panels, Batteries or Solar Water Heating?

APN Home helps homeowners understand the type of support they may need for home improvement projects, including solar panels, battery storage, solar water heating, roof upgrades, extensions, rewiring, insulation, heating systems and wider energy improvements.

Whether you are considering roof-mounted solar panels, solar roof tiles, battery storage, solar thermal hot water or a full home energy upgrade, it is worth getting the system design and payback clear before placing an order.

Tell us about your project and APN Home can help you understand the next sensible step.

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