Solar Panels & Underfloor Heating: Here’s How

If you are looking for a green-energy way to heat your home or outbuildings, you might wonder if you can use solar power as the power source for underfloor heating.

Quite simply, you can. However, there are some essential bits that you will need to know before adding solar as your energy source for underfloor heating systems. 

We already know solar panels can power underfloor heating, but there is a right and wrong ways to go about that process. The good news is that we sort that out for you in this blog. 

In this blog, we discuss

  • Whether you can use solar panels to power an underfloor heating system. 
  • The two types of underfloor heating systems and how they differ
  • What is the best underfloor heating system, and why
Underfloor Heating
Underfloor Heating

Can solar panels run underfloor heating?

Solar energy can run underfloor heating. The big question here is whether you mean, “can solar power heat the water for underfloor heating,” or do you mean can solar power directly heat underfloor heating systems? 

There are two ways of powering the underfloor heating. They are:

A holding tank is full of water and then heated, forcing the water through a system of pipes under the floor. The heat transfer causes the underfloor space to heat and radiates through a solid surface.

In this case, solar energy would be the power source that heated the water in the storage tank.

You could use solar energy to do this, but it is not very efficient, and it could lead to issues such as insufficient or reserved power (battery depletion.)

The other option is to use an electric mat that you power directly from the solar array. The process is more efficient than heating water and is much faster.

The electric mat is built into the subfloor or the floor itself and then backed with materials that cause the heat to radiate to the floor. 

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Grouo Of Workera Installing Underfloor Heating And Colling In Modern Home - Sol Voltaics: Solar Panel Information
Grouo Of Workera Installing Underfloor Heating And Colling In Modern Home

How Does Solar Underfloor Heating Work?

As we described above, two methods of creating radiant heating for floors exist. The first is to pump hot water through pipes under the floor. The second is to use electricity to heat a wire mat which then radiates heat. 

Indirect heating, the hot water method, is an inferior energy use. Water is a sink for energy.

  • You can think about a hurricane. For a hurricane to form, the water must reach 80°F at 200 feet deep. That’s a lot of heat.

The same is true when you heat water stored in a container. It takes a lot of energy to heat 500 gallons of water, especially when the weather outside is cold. You would need a significant amount of solar energy.

That means your solar array would need to be overly large with battery backup systems that could handle the extra energy needed to heat the water to heat the floor. 

Laying An Electric Underfloor Heating Under A Cement Screed Close Up. - Sol Voltaics: Solar Panel Information
Laying An Electric Underfloor Heating Under A Cement Screed Close Up.

Direct heating, the electric mat method, takes less energy to run it. You could shuttle excess energy from your solar array into the floor mat to power it since that energy would be wasted if not consumed.

The solar array would be smaller than one that usage included heating water. The battery backup supply would also be smaller since less energy is needed. 

The solar circuit, which moves energy from the panels to the controller, the batteries, the inverter, and then to the house, often has extra energy if the batteries are full.

That energy either goes into the utility grid or dissipates and is wasted. When you use a direct method to power an underfloor heating system, you have the opportunity to use energy that you would otherwise be wasting to power the floor heating system.

So, in a way, you are making the world greener when you go with a direct source over an indirect source of power for underfloor heating units. 

A Roll Of Film Underfloor Heating Lies On The Insulation. - Sol Voltaics: Solar Panel Information
A Roll Of Film Underfloor Heating Lies On The Insulation.

Can solar panels be used for heating?

You can use the energy from solar panels to create heat for a home or business.

Heating a home and cooling a home are two of the most significant usages of energy, and solar energy is a very green way to power both heating and cooling.

The positive is that using solar energy to heat or cool your home or business significantly drops your monthly power bill. 

Solar energy can heat your home if you use underfloor heating systems or a conventional HVAC.

However, it would be essential to include a battery backup system with enough batteries to power the home’s standard energy requirements and an underfloor heating system. 

Pipe Fitter Mounting Underfloor Heating. Heating System And Underfloor Heating. - Sol Voltaics: Solar Panel Information
Pipe Fitter Mounting Underfloor Heating. Heating System And Underfloor Heating.

What Is The Best Heating System For Underfloor Heating?

The direct heating source is better for the two types of underfloor heating systems we discuss here. If you live in a mild climate, either method may be okay.

However, in terms of energy use, the direct heating method is by far more efficient.

The benefits of using a direct heating system include:

  • Smaller Solar Array Requirements — You do not need as many solar panels to run a direct underfloor heating system because there is lower energy usage. 
  • More applicable on cloudy days due to the lower energy requirements — On cloudy days, there is less incoming solar radiation which means the solar array produces less energy. With the direct underfloor heating system, you would likely still have the energy to power the system, even on cloudy days. 
  • Decrease in Annual Energy Usages — Because the system uses less energy than an indirect underfloor heating system, your household uses less energy annually with a direct underfloor heating system. 

Indirect or Direct Heating using Solar

Other considerations make deciding between an indirect underfloor heating system and one that uses direct energy.

Climate

In milder climates, either system works well; you will have to utilize more energy to heat the water in an indirect underfloor heating system than you would with a direct system.

On the other hand, if you live in a colder climate, you would use more energy each year, heating the water in the indirect underfloor heating system.

That can be problematic if the cooler months have more clouds, storms, or snow

Solar Array Size

You could use either method to heat your home if you have a large solar array.

If you have a smaller array, you would want to use the direct heating underfloor heating system because the energy demands are much smaller than the indirect heating system.

Another consideration here is the amount of wasted energy that your array produces. If there is a lot of wasted energy, you could utilize it for an underfloor heating system (Indirect) with water tubes and a reservoir. 

Grid-tied vs. Off-Grid

With an off-grid solar array, your energy is limited by how much energy the array produces, the number of solar batteries in your energy storage system, and how much energy your home requires.

A direct power underfloor heating system would be best for off-grid or mobile living situations (caravan.)

If grid-tied, you could use either system, though you’d likely pay more money each month to the utility company if you went with an indirect underfloor heating system.

Sources

General Solar Panel FAQ

What Problems Do Solar Panels Solve?

In environmental terms, solar panels can potentially solve a handful of problems, including;
1. Air pollution
2. Water pollution
3. Greenhouse gases
4. Reduction in fossil fuel use

For individuals, solar energy allows you to become completely self-sufficient when it comes to your electricity needs and can save you a lot of money in the long run.

What Are 3 Important Uses Of Solar Panels?

The three most important uses of solar panels are;
1. Solar electricity. This can be used to power almost any appliance in your home, including TVs, computers, and fridges.
2. Lighting. In addition to the use of low-power, LED lightbulbs, solar panels can provide an efficient, low-cost, and environmentally friendly way to provide lighting to homes. 
3. Portable solar. In our modern, always-connected lives, our phones, tablets, and computers are almost always with us, and all run on batteries. Portable PV chargers can help keep our batteries topped up no matter where we are, as long as there is some sun to charge them.

Do solar panels give you free electricity?

Once the cost of the array is paid in full, the energy it produces is free. There are ongoing maintenance costs, too, such as annual panel cleaning, etc. 

How much will my electric bill be with solar panels?

Suppose your solar array includes a solar battery backup system, and it is large enough to fully cover your energy usage per day. In that case, your monthly electric bill will be next to zero dollars, even with a grid-tied system. 

If your solar array does not include a solar battery backup system, then at night, your house or business will use grid electricity. That cost will vary but expect to pay from 1/3-2/3 of your average electric bill, and that cost will fluctuate seasonally. 

Do you save money with solar panels?

The simple answer is, Yes, you save money with solar panels. There is an initial upfront cost, but since solar panels are warrantied for 25 years, you will save money over time. You will also begin to see monthly savings in energy bills, but there are other ways that solar panels pay you back. Those include:
1. Adding value to your home or commercial building 
2. Monthly decreases in energy costs
3. The ability to add more energy appliances without increased monthly costs
4. The potential for tax credits for going solar

Can solar panels power a house 24-7?

Most definitely! Solar panels can certainly power a house 24-7, with the addition of a high-quality inverter and a suitable battery bank, of course. To power, a house under normal usage will require a massive solar array, though, and there will be a very expensive initial financial outlay.

Do I need to tell my energy supplier I have solar panels?

This depends on where you live, but in most cases, it’s not necessary to inform your energy supplier that you have solar panels. That said, you may be producing excess power with your solar system, in which case you may be able to sell that excess power back to energy companies.

In this case, you’ll naturally need to be in contact with them. 

What Are Solar Cells Known as and Why?

Solar cells are also called photovoltaic (PV) cells. They are called so because the term ‘photovoltaic’ literally means light i.e. photo and electricity i.e. voltaic.

These cells generate electricity through the photovoltaic effect. This effect basically causes the generation of free electrons from the semiconducting silicon material of the solar panel when sunlight hits its surface.

What Type of Solar Panels Are Most Efficient and Why?

There are currently three types of solar panels available in the market that are:
1. Monocrystalline
2. Polycrystalline
3. Thin-filmed

Among these, monocrystalline solar panels are known to be the most efficient among all others.

Does heat enter your home through the roof?

Absolutely. Heat enters your home through your roof, and on a hot day your attic can get up to 150 degrees Fahrenheit or more. Through conduction, heat from the sun warms your roof which then warms your attic and the rest of your home.

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