Photovoltaic vs Solar Thermal Panels – Key Differences for UK Properties

Understanding the differences between solar photovoltaic (PV) and solar thermal panels is crucial for making an informed investment decision. As energy prices soar and environmental concerns grow, UK homeowners, landlords, and commercial property owners are increasingly turning to solar energy to power their properties sustainably. 

This guide breaks down the key distinctions, benefits, and drawbacks of both technologies in simple terms, helping you choose the best solar solution for your needs.

Solar Photovoltaic vs Solar Thermal Panels: A Quick Comparison

To help you grasp the core differences between solar photovoltaic and solar thermal panels, we’ve compiled a straightforward comparison table. This highlights key factors like efficiency, costs, and best use cases to guide your decision-making process.

Solar Photovoltaic (PV) Panels

Solar PV panels use semiconductor materials, typically silicon, to convert sunlight directly into electricity via the photovoltaic effect. When sunlight hits the panels, it excites electrons, creating a direct current (DC). 

An inverter then converts this into alternating current (AC) for household use or grid export. According to the Energy Saving Trust, a typical 4kW PV system in the UK can generate around 3,800 kWh of electricity annually, covering a significant portion of a household’s energy needs.

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Solar Thermal Panels

Solar thermal panels absorb sunlight to heat a fluid (usually a water-glycol mix) circulating through tubes in the panels. This heated fluid transfers its warmth to a hot water cylinder via a heat exchanger, providing hot water for showers, baths, or heating. 

According to the UK Government, solar thermal systems can meet up to 50% of a household’s annual hot water demand.

Solar Photovoltaic vs Solar Thermal Panels: What Are the Key Differences?

To help you decide which system suits your property, we’ll break down the key differences across critical factors like efficiency, costs, and suitability. Each section evaluates both technologies to determine a winner based on practical considerations for UK homeowners and landlords.

Efficiency

Solar thermal panels excel at capturing heat, with efficiencies of up to 70%, making them ideal for water heating. 

In contrast, solar PV panels convert 15-22% of sunlight into electricity, which is less efficient but more versatile for powering a home. 

For example, a 4kW PV system generates around 3,800 kWh annually, while a solar thermal system can cover 50-60% of hot water needs. 

Winner: Solar thermal for efficiency in heat capture; solar PV for versatility.

Insight: Read our in-depth guide on solar panel efficiency to learn more.

Aesthetics

Solar PV panels offer a sleek, modern look with uniform designs that blend well with most roofs. 

Solar thermal panels, with visible pipes and bulkier collectors, can appear less attractive and may not suit properties where aesthetics are a priority. 

Winner: Solar PV for a cleaner, more modern appearance.

Installation Requirements

Solar PV systems require significant roof space (20m² for a 4kW system) and an inverter to convert DC to AC electricity. They integrate easily with existing electrical systems. 

Solar thermal systems need less roof space (3-6m²) but require a hot water cylinder and plumbing modifications, which can complicate installation in homes without existing cylinders.

Winner: Solar PV for simpler integration with most properties.

Tip: Not sure how much roof space you will need? Read our guide on how many solar panels you can fit on your roof to get a better understanding. 

Costs

A 4kW solar PV system costs around £6,400, while a solar thermal system averages £6,000. However, PV systems offer greater long-term savings through SEG payments and reduced electricity bills (up to 86% bill reduction for a typical household).

Thermal systems save on gas bills but offer fewer financial incentives. 

Winner: Solar PV for better long-term value.

Use our Solar Panel Calculator to find the ideal system size for your home and see how much you could save on electricity bills.

Performance

Solar PV panels produce electricity year-round, even on cloudy days, though output drops by 10-30%. 

Solar thermal systems are less effective in winter due to shorter daylight hours but store heat for consistent hot water supply. 

Winner: Solar PV for reliable year-round performance.

Best Suited to Which Property Types

Solar PV is ideal for commercial buildings, homes, or flats, with high electricity demands or space for panels. 

Solar thermal suits properties with high hot water needs (e.g., family homes with 4+ occupants) and existing hot water cylinders.

Winner: Solar PV for broader applicability across property types.

Maintenance and Servicing

Solar PV systems require minimal maintenance, occasional cleaning and inverter checks every 5-10 years. 

Solar thermal systems need regular servicing to check for leaks, replace antifreeze, and maintain pumps, increasing long-term costs. 

Winner: Solar PV for lower maintenance needs.

Lifespan

Solar PV panels last 25-30 years, with inverters replaced every 10-15 years. 

Solar thermal systems typically last 15-20 years due to wear on mechanical components like pumps and pipes. 

Winner: Solar PV for longer lifespan.

Solar Photovoltaic vs Solar Thermal Panels: Which Should You Choose?

Choosing between solar PV and solar thermal depends on your energy needs, property type, and budget. To make the decision easier, here’s a breakdown of who each system is best for and when to choose it. Ready to explore your options? 

Solar Photovoltaic (PV) Panels

Who’s It Best For:

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  Homeowners or landlords with high electricity usage (e.g., electric heating, EV charging).
• •
  Properties with ample roof space (20m² or more).
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  Those seeking long-term savings through SEG payments or battery storage.

Who It’s Not For:

• •
  Households with minimal electricity needs and high hot water demand.
• •
  Properties with limited roof space or no access to grid connections.

Choose It If:

• •
  You want to power household appliances, lighting, or an entire home.
• •
  You aim to reduce electricity bills by up to 86%.
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  You’re interested in earning income through excess electricity export via SEG.
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  You prefer a low-maintenance, long-lasting system (25-30 years).

Solar Thermal Panels

Who’s It Best For:

• •
  Families or properties with high hot water demand (e.g., 4+ occupants).
• •
  Homes with existing hot water cylinders or compatible plumbing.
• •
  Those prioritising water heating savings over electricity generation.

Who It’s Not For:

• •
  Properties with low hot water needs or no hot water cylinder.
• •
  Those seeking versatile energy solutions for broader household needs.

Choose It If:

• •
  You want to cut gas bills for water heating by £80-£120 annually..
• •
  You have limited roof space (3-6m²).
• •
  You’re focused on efficient water heating rather than electricity production.

FAQs

Can I combine solar PV and solar thermal systems?

Yes, hybrid systems combining both technologies exist, allowing you to generate electricity and heat water. These are ideal for larger properties with diverse energy needs but may require higher upfront costs and more complex installation.

Do solar panels work during power outages?

Solar PV systems connected to the grid typically shut off during outages for safety. Off-grid PV systems with battery storage can provide power. Solar thermal systems continue to heat water if the pump is powered, often requiring a backup power.

Are there planning permissions required for solar panels in the UK?

Most solar PV and thermal installations fall under permitted development rights, but listed buildings or conservation areas may require planning permission. Always check with your local council.

How do weather conditions affect solar panel performance?

Solar PV panels generate less electricity in rain or heavy cloud cover (10-30% reduction), while solar thermal panels struggle in cold, overcast conditions due to lower heat capture. Both perform best in sunny weather.

What is the payback period for solar panels?

Solar PV systems typically have a payback period of 8-12 years, depending on electricity savings and SEG earnings. Solar thermal systems have a payback period of 10-15 years, influenced by gas bill savings and system costs.

Our Verdict

Deciding between solar photovoltaic and solar thermal panels comes down to your property’s energy needs and priorities. 

Solar PV offers versatility, long-term savings, and a longer lifespan, making it ideal for most UK homeowners, landlords, and commercial properties aiming to reduce electricity bills and earn SEG payments. 

Solar thermal, with its high efficiency for water heating, suits households with significant hot water demands and limited roof space. 

By understanding factors like efficiency, costs, and maintenance, you can make an informed choice. Start your solar journey today with Eco Answers’ Quote-Comparison Tool to find the best solar solution for your property.