Solar Heating System

Difference Between Active and Passive Solar Heating Systems

There are two main ways to use the sun’s warmth to heat your home: passive solar and active solar systems. Both capture the sun’s heat, but they do it in different ways. Passive solar systems use your home’s design to trap the sun’s warmth. Consider large windows facing south to soak up the winter sun or strategically placed overhangs to shade windows in the summer.

Active solar systems use collectors on your roof to capture the sun’s heat. A pump then moves this warmed liquid or air to heat your home’s water or air directly. Solar thermal heating systems can reduce your carbon footprint and utility expenses through a renewable source.

Why Consider Solar Thermal Technology?

While many of us are familiar with the electricity-producing capability of solar panels, a less discussed but equally impactful technology is solar thermal panels. Originating as the first commercially available solar technology in the UK, these panels harness sunlight to produce heat, not electricity. Solar thermal panels are also known as solar water heating collectors.

Solar thermal technology captures heat waves, which inherently carry more energy than visible light. This direct conversion to heat, without the intermediate step of electricity generation, makes them remarkably efficient.
Not only are they more affordable upfront, but their shorter payback period compared to PV panels makes them an economically sound choice.
With warranties ranging from 5 to 10 years and lifespans extending up to 25 years, solar thermal panels ask for little beyond installation. The simple tech means minimal upkeep.
They’re robust against the elements, performing reliably in cold, overcast, or windy conditions. Solar thermal heating systems also include an energy storage solution to capture heat for later use.
By opting for solar thermal, you’re looking at up to 600 kg less in carbon dioxide emissions annually and significant reductions in heating bills.
Beyond the environmental and direct financial savings, the Renewable Heat Incentive (RHI) offers yearly payments based on your household size and installation specifics.

Types of Solar Thermal Panels

Solar thermal panels or solar water heating collectors are installed on roofs to capture the sun’s heat, efficiently using it to warm water within a storage cylinder. The system circulates a solution, composed of water and antifreeze, through the panels to absorb and transfer heat. Here’s a quick breakdown of the two main varieties.

Flat-Plate Collectors

They resemble solar PV panels and include a dark absorbing surface under a transparent cover, insulated backing, and a crucial fluid for heat transfer to a water tank. Their absorbers can be crafted from polymers, copper, aluminium, or steel. While copper stands out for durability and conductivity, polymer collectors excel in colder climates due to their freeze tolerance.

Evacuated Tube Collectors

They are composed of numerous glass tubes within which the heat-transfer fluid flows. Their design makes them exceptionally efficient in cold weather because they virtually eliminate heat loss, thanks to the vacuum within the tubes. However, in warmer climates, their efficiency can slightly decrease due to overheating risks. What sets them apart is their structure, which allows snow to simply fall through the gaps, ensuring minimal efficiency loss from snow cover—no radiated heat means no melting snow.

Uses for Solar Thermal Heating Systems

Here’s a brief rundown on how these systems can transform energy usage in homes and businesses.

Solar Water Heating

Switching to solar water heating is a powerful move for those aiming to cut down on traditional energy costs. You have options between passive and active setups. Passive ones rely on gravity and natural circulation, whereas active systems use pumps and controls for circulation.

The initial investment in solar water heating pays off differently for everyone, depending on your current heating method. Electricity and gasoline replacements see quicker returns than natural gas due to cost differences. A solar water heating system not only offers annual returns but also increases property value with the growing trend toward green technology.

Solar Space Heaters

Solar space heaters harness solar energy to heat homes, similar to solar water heating but on a larger scale, requiring more collectors and larger storage units. They can be both passive, working like greenhouses to naturally trap and circulate heat, or active, using pumps to distribute heat. What’s impressive is the potential for up to a 70% reduction in heating costs. Although most building codes necessitate a backup heating system, integrating solar space heaters with existing systems can provide an efficient and cost-effective way to stay warm.

Solar Pool Heaters

A solar pool heater circulates pool water through solar thermal panels to warm it before returning it to the pool. This system is not only low on maintenance but can also extend your pool usage season, with the initial investment often recouped within seven years.

How Much Can You Save With Solar Thermal Heating Systems?

Heating bills are consistently one of the bigger monthly expenses for many homes. With solar thermal systems, there’s a substantial opportunity to cut those costs. Typically, a solar thermal setup can furnish about 60% of your hot water needs throughout the year—this figure could rise with minor tweaks in daily water use habits.

While the initial setup cost ranges between £3000 and £6000, the Renewable Heat Incentive (RHI) scheme compensates homeowners with quarterly payments over seven years, based on the current RHI rate of 19.2p per kWh.

By integrating solar thermal panels, you can expect around a 10% reduction in energy bills. With these systems lasting up to 25 years and the outlook for electricity and gas costs expected to rise, your savings could increase even further down the line.

During times with lower sunlight, like winter months, the solar thermal system might not be able to fully meet your hot water needs. A boiler can act as a backup, kicking in to heat the water further and ensure you always have hot water available. If your boiler is old and inefficient, you can apply for a free boiler grant through the Warmer Homes website.

Are Solar Thermal Panels Suitable for Your Home?

Ideal conditions for these panels include a south-facing orientation. However, they remain effective on southwest or southeast-facing roofs. An alternative for non-ideal roofs is ground installation, provided there is access to direct, unobstructed sunlight.

Before investing, assess compatibility with your home’s appliances. Electric showers and cold-fill appliances might not be the best match for solar water heating systems. Also, if your current hot water cylinder cannot accommodate solar thermal technology, consider upgrading to a compatible one or explore thermodynamic panels as a flexible addition to any system.

On a per-person basis, solar thermal panels require between 1 and 2 square meters of space and should be angled between 20 and 50 degrees for optimal sunlight absorption.

If you are looking to get a solar heating system fitted to your home, fill out the form on the Home Energy Guide website, and we will get one of our team of experts to guide you through the process. We will advise on what system best suits your property and connect you with the highest rates suppliers in your area.