Solar PV Panels vs Solar Thermal Panels: Which Is Better?

Solar PV panels turn sunlight into electricity to power appliances in your home or business. However, solar thermal panels harness sunshine to heat a fluid that can be used to heat water or space.

In this article, we’ll highlight the differences between the two systems regarding costs, efficiency, installation, and appearance. We’ll also discuss their lifespans and warranties.

Key Takeaways:

• Solar PV panels are best for generating green electricity for homes and businesses.
• Solar thermal panels are best for heating water for homes and businesses without burning fossil fuels.
• PV panels are more expensive – over £12,000 with battery storage – but funding grants are available.
• Thermal panels are cheaper to install – around £5,900 – but may require more maintenance.
• PV panels require a fairly sizable section of roof space.
• Thermal panels need less installation space.
• Thermal panels perform up to 4x more efficiently than PV systems.

Solar PV vs Solar Thermal Panels: A Detailed Comparison

Let’s break down how PV and thermal panels compare on costs, efficiencies, longevity, and other key variables.

Cost

• Solar panels:  Installing a 4 kW system, which is a common home setup, costs between £7,000 and £8,000. An energy storage battery adds an additional £5,000. A large commercial system can cost over £50,000. However, there are grants for solar panels to help property owners invest in this technology.
• Solar thermal panels: An average UK solar thermal system costs £5,921, according to Microgeneration Certification Scheme figures. Home Energy Scotland offers loans towards installation costs.

There is also currently 0% VAT on both solar thermal and PV panels.

Performance and efficiency

• PV panels: Solar panel systems provide efficiencies between 15% and 23%. This means the best units can convert 23% of the sun’s energy into electricity. Advances in solar technology are pushing efficiencies towards 30%. However, performance drops sharply in winter’s weaker, scarcer sunlight.
• Solar thermal: Solar thermal systems boast efficiencies between 70-90% in good sunlight. Because it relies on heat, thermal is much less effective in winter.

Installation

• Solar PV: Installing solar PV panels involves attaching the panels to mounting hardware on the roof or ground rack. The panels are connected to a solar inverter which converts the DC current from the panels into AC current to power appliances in a home or business. Installation can take one day for a small residential system to a few weeks for a large commercial setup.
• Solar thermal: Panels (also called solar thermal collectors) are mounted on the roof or a ground-based structure. Insulated pipes are connected to carry a heat transfer fluid – usually a water-glycol mix. A pump and control system are integrated to circulate the heat transfer fluid and bring heat indoors. Installation takes under a day to a week depending on the system size.

Size and space

• PV panels: An average solar PV panel measures around 1.7 m x 1 m. Allowing for the space between panels in an array each panel requires around 2 sq m of surface area. A 4 kW system of 10 x 400 watt panels will, therefore, need about 20 sq m of space.
• Solar thermal: The average solar thermal panel is slightly larger than a PV panel. That said, the greater efficiency of solar thermal units generally makes them more space-efficient. A thermal energy system may only need two to four collectors. Four collectors will require 10 sq m of space.

Design and aesthetics

Solar PV: Sleek, rectangular, blue or black solar PV panels are now a common sight on roofs across the UK. These panels house solar cells under a protective glass covering with insulation on the back and sides.

Alternatives to roof-mounted solar PV systems include:

• Integrated PV panels – designed to fit flush into the roof.
• Ground-mounted solar panels.

Solar thermal: The two main designs are:

• Flat plate collectors have a similar rectangular, dark appearance to solar PV panels. They incorporate a dark absorber plate with integrated piping under protective glass.
• Evacuated tube collectors consist of a series of glass tubes, each with an inner tube. A vacuum between the cylinders lets the sun’s radiation pass to the inner tube containing the transfer fluid.

Lifespan and warranties

• Solar PV: The modern solar PV system is made to be tough and durable. Quality solar panels have a lifespan of 25-30 years. They can withstand hail and storms and function in temperature extremes from over 60°C to below -30°C. The best product warranties may cover you for 15+ years.
• Solar thermal: The standard solar thermal system has a slightly shorter lifespan than its PV counterpart – up to about 20 years. The best products may last for 25 years. Expect 10-year warranties on collectors with warranties on pumps and controllers limited to 5 years or less.

Maintenance

• Solar PV: Solar PV panels are low-maintenance. Cleaning your panels periodically, checking for cracks, corrosion, and loose connections, and protecting the system against birds and wildlife will help prevent common solar panel problems and ensure longevity.
• Solar thermal: Maintaining thermal systems is more complex. The heat transfer fluid and system pressure must be properly maintained. Additionally, components like pumps and valves can wear and fail. Monitoring for and preventing scaling (mineral buildup) and corrosion is important.

Solar PV Vs Solar Thermal: Which is Best For You?

While both solar PV and solar thermal technology cut your carbon footprint significantly, each has its advantages.

PV solar panels are best for

• Reducing your energy bills.
• Securing greater electricity independence.
• Producing clean, green solar power for your electric boiler, EVs, electric heater, and more.
• Generating electricity you can sell back to the grid through the Smart Export Guarantee.

Solar thermal panels are best for

• Reducing your annual heating costs.
• Delivering hot water to larger properties with a consistent, high water demand.
• An eco-friendly solution when roof space is limited.

Are You Ready For a Solar Installation Quote?

To join the millions benefitting from lower energy bills and higher property values, contact Eco Happy today. Provide a few quick details to get a no-obligation solar installation quote.

Eco Happy is a trusted solar installer in England and throughout the UK. We’d be happy to get you started on your solar power adventure.

FAQs

Can solar thermal panels provide enough hot water for my home in winter?

Solar thermal systems usually cannot meet a home’s hot water demands in winter. While summer provides enough sunlight to deliver plenty of hot water, winter demands must be supplemented by a backup system – a conventional boiler or heat pump.

Do solar PV panels need direct sunlight?

Not necessarily; however, solar PV systems generate the most solar power in direct sunlight. They also capture diffuse light scattered by clouds to generate energy, though this indirect light produces a lower yield.

How many solar thermal panels do I need?

Using flat plate collectors, one panel should produce enough hot water in summer for a small household. A larger household will need 2-3 panels. Using evacuated tube collectors, you need about 20 tubes for a small household and 30 tubes or more for a larger one.

Final Verdict

Solar PV panels offer clean electricity but require more roof space and upfront costs. Solar thermal panels, on the other hand, excel at water heating and are more affordable.

Each technology offers unique advantages depending on your energy priorities. However, both cut your energy bills and reduce your carbon footprint.