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If you’re considering getting a solar thermal system, one of the first things that comes to mind is the possibility of the system functioning properly during the cold months. The short and simple answer to this question is yes, a solar thermal system works in the winter. However, the downside here is that it’ll be a lot less efficient when compared to how it operates during the warmer months or summer. As a result of this fact, you’ll likely need to rely more on your boiler, immersion heater or any other backup heating system during this period as your solar thermal system will fail to contribute as much as it does during the warmer months. So what exactly is the reason why solar thermal is less effective and less efficient in the winter period? Let’s have a look!

As you know, solar thermal system banks on the sun’s energy to heat the water for your home’s use. During the cold months or winter, the sunlight becomes a lot less available when compared to the warmer months, as a result, there’s less sunlight that’s available to be used for its solar energy. And even more so at the periods when the days are shorter or skies are clearly overcast.

Also having a great impact on a solar thermal system’s output is heavy snow. Flat plate collectors normally have the capacity to cope better during snowy conditions as the light that’s able to travel through the snow will heat up the absorber plate - thereby making the snow slide off more quickly. However, the case is contrary with evacuated tube collectors which possesses a form of vacuum insulation that’s crafted to minimize the loss of heat, meaning they can’t generate heat to melt and cause the snow to slide off in a similar way.

If you’re thinking about installing a solar thermal system in your house, it’s always important to put into consideration numerous factors before you proceed. While some solar thermal systems are suitable for use at home, there are also some that are suitable for businesses or organizations which normally requires a big amount of hot water like hotels, restaurants, schools, hospitals and many more. You’ll also find some types available in the market that are suitable for communities to satisfy communal hot water demands.

It should, however, be noted that solar thermal systems do not have the capacity to produce all the hot water demand of a house. In the UK, an average household will need an annual water heating of between 3000kWh to 5000kWh. Whereas, a solar thermal system is only able to meet about 40 percent to 60 percent of this demand.

With that in mind, it’s also worth noting that during the summer months when the solar radiation is at its peak and hot water demand is relatively lower when compared to other seasons, a solar thermal system may be able to provide all of your household’s hot water needs. This implies that during this period you may not find the need to operate your boiler at all. However, during winter or colder months, when you have a higher hot water demands in contrary to a lower solar radiation, a solar thermal system will only be able to take care of about 20 percent of your household’s hot water needs. And that ultimately implies that during this period, you’ll need to rely more on a alternative or backup source of heat like gas, coal, electricity, oil or LPG.

It may be hard to believe with the summers we have in the UK, but there is more than enough sunlight to power solar panels. Solar PV (photovoltaic) panels operate in daylight, rather than needing direct rays from the sun so they’ll work throughout the year.

If you’re thinking about getting a solar thermal system for your home, it’s normal to consider the possibility of using the system for central heating. So is this viable? In this article, you’ll learn how solar thermal panels can be incorporated for heating. Let’s have a closer look!

Heating and hot water systems, on the average, takes up a sizeable part ( up to 70 percent) of our energy bills. Now take a moment to imagine how cool it’ll be to generate your own hot water for free without having to depend on any supplier which in turn significantly reduces your energy bills. Well, this is exactly the work of central heating systems that are powered by solar. That’s super cool, right? Well, let’s have a look at how this works.

While solar panels generates electricity, solar thermal panels produces heat for hot water production. However, what’s important is the fact that they both make use of the sun’s natural energy to provide us with a free and renewable energy we can use in our homes. Here’s how it works.

Solar thermal panels directed at central heating incorporates the sun’s natural energy to heat water in a storage cylinder which is then available for use at home. These solar thermal panels are exposed to the sunlight by fitting them on the roof of the home. Generally, they’ll include tubes that contains liquid whose job is to collect the heat and then transfer it to a hot water cylinder that’s solar compatible in your home. The heat is generated for free and is also renewable. This is help you save lots of money on oil, gas and even electricity which you purchase to power the cylinder.

It’s vital to purchase a solar panel system that suits your property. If you’re investing in a solar panel system, it makes the most financial sense to get the biggest one possible. However, whether you can do this or not depends on budget and space.

Here’s an idea of how much roof or ground space you’ll need to install a few different sizes of commercial solar panel system.

Solar panel system size, No. of solar panels, Approximate area required

11kW, 44, 64m²

20kW, 80, 116m²

30kW, 120, 173m²

40kW, 160, 231m²

50kW, 200, 288m²

There are a few trusted companies in the UK that make solar panels. While there are other solar thermal panels out there that are made by Chinese and American companies, we’ll focus on the brands with a longstanding presence in the UK since these are the panels MCS-registered solar companies are likely to recommend to you.

Viessmann, Worcester Bosch, Solar UK and Dimplex make some of the best solar thermal panels in the UK. Dimplex and Viessmann offer both flat plate and evacuated tube solar panels, while Solar UK only offers evacuated tubes. Worcester Bosch’s Greenskies range are all flat plate collectors. Viessmann’s panels come with a 5-year warranty, while Worcester Bosch and Dimplex offer extensive 10-year warranties. However, Solar UK offer a comprehensive 25-year warranty and guarantee that the panels will deliver the same level of performance for 25 years!

We’d recommend choosing evacuated tube solar thermal panels because they are the most efficient. While there won’t be much difference between evacuated tubes and flat plates in the summer, in the winter evacuated tubes are much better at taking heat from the sun than flat plates. Since our winters are long and cold with few daylight hours, we think it makes sense to go with evacuated tubes. However, if your priority is looks over maximising efficiency, you might want to choose flat plate collectors since they sit flat on the roof and look more like solar PV panels, whereas the evacuated tubes will stick out.

If you want to test your solar panel system to see if it’s working properly or just to see what output it’s giving, you can do this using a multimeter to measure current, or amps, and voltage.

Before you start, you’ll need to find the voltage (v) and current (A) ratings of your panel. You should be able to find them on the back of the panel. You should also make sure that it’s a nice clear, sunny day to get the best readings out of your panel. You should also check that it’s safe to be up on your roof!

To measure open circuit voltage, you’ll need to make sure that your solar panel is completely disconnected from your system’s regulator and battery (if you have one). Angle the panel towards the sun, and ensure that your multimeter is set to measure volts. Measure the voltage between the positive and negative terminals by connecting the negative contact on the voltmeter to the negative on the panel and the positive contact on the voltmeter to the positive on the panel.

Then, you can move on to the short circuit current. Follow the same steps as the open circuit voltage, but ensure that your multimeter is set at 10A to start with.

Only try to test your solar panel if it’s safe to do so. If your roof isn’t accessible without scaffolding or specialist equipment, consider speaking to an MCS-registered solar company about your concerns. They may recommend that they come to service your solar panel system.