Should You Add a Small Solar Heater In A Greenhouse?

Last Updated on April 5, 2024 by Real Men Sow

Gardeners are always looking for new ways to heat their greenhouse, and one of the best ways is to use the sun. There are several options to use solar energy to heat your greenhouse.

Although solar-electric heaters are available, they’re incredibly inefficient, since they need to first convert solar energy to electricity, and then to heat. Better options for solar greenhouse heating are: thermal mass, solar hot water heating (hydronic heating), and heat exchangers.

Different Heating Method with Pros and Cons

  • Hydronic heating (solar hot water) – This is an energy efficient heater that requires very little upkeep. It’s very quiet and has a very consistent temperature. However, it usually requires professional installation and it’s expensive to install.
  • Photovoltaic (PV) solar panels – This heater is usually easy to buy and set up. However, it is a very inefficient heat source because it can require a lot of surface are and pv panels are expensive.
  • Heat Exchanger – This heater is fairly efficient, it’s easy to install and doesn’t require professional expertise. It also distributes heat fairly evenly in a greenhouse. However, it is not as efficient as a hydronic heater because it uses a fan and not a boiler. This means that you may not be able to heat your greenhouse in cloudy weather.

Solar Hot-Water Panels

What are solar hot-water panels, and how do they work?

Heating greenhouses with hot water is a common way to heat them. Hydronic heating, also known as solar hot-water heating, is energy efficient and safe for both your greenhouse and the plants within.

Solar hot-water heating is achieved by the sun warming water in panels. The water can then be heated further using a boiler. The hot water is circulated by a pump through the tubes in the greenhouse floor. The water is then cooled and returned to the greenhouse floor. This helps reduce resources.

How To Setup And Use Solar Hot Water Panels

It can be difficult to install a hydronic heating system. This is usually done while the greenhouse is being constructed. If you don’t have the skills and confidence to set up complicated heating systems, it’s best to hire a professional plumber who is experienced in installing hydronic heating systems.

Yes, it can be expensive. It could cost anywhere from $10,000 to $20,000 depending on how big your greenhouse is.

Hydronic heating systems might need a boiling system in order to properly circulate heated water. Unfortunately, this would cost you thousands of dollars. To circulate heat, you would need to install pipes underneath the floor.

You can also keep water in barrels, and then use a pump to circulate the water under a stone-tiled floor. Although this option is cheaper and more effective than professional services, it will likely require more upkeep.

Benefits Of Using Solar Hot-Water Panels

Solar hot water panels are a great way to invest in your greenhouse. Water heating is a great way to heat the planet. It’s also very efficient in terms of energy. Through solar hot-water panels, the water is heated to make it heat up.

After the water cools it can be recycled and used to heat your greenhouse again. This could save you anywhere from 70 to 80% on heating costs, especially if your climate is colder and you need to heat your greenhouse more frequently throughout the year.

Hydronic heating can be a great option for people who wish to grow vegetables but don’t live in warm climates. Heating costs can quickly add up, and it can be difficult to grow plants outdoors when the weather suddenly turns cold. Hydronic heating is a cost-saving option that maintains a constant temperature in the greenhouse.


The size of your greenhouse will determine the cost of a hydronic heating unit. The minimum cost of a hydronic system is $6.00 per sq. ft. This can be compared to an electric heating system which costs $8.00 per sq. ft.

Hydronic systems might be more affordable than propane or forced air furnaces. However, it will depend on how big your greenhouse is and how sunny your climate. There are many factors to take into consideration. If you live in a sunny area, solar hot water panels are a great investment to heat your greenhouse.


Hydronic heating systems use very little energy. They are less expensive than traditional heating systems and can keep a room’s temperature constant for longer periods of time.

A hydronic heating system can be a great solution for plants growing in a greenhouse. The water can even be recycled to heat your greenhouse again and again. This is good for both the environment and your wallet.

Photovoltaic (PV) solar panels

What Are Pv Solar Panels?

When you hear the term “solar panel”, PV solar panels is probably what you associate with. These panels convert sunlight directly into electricity. To heat your greenhouse you would need to convert the electricity into heat.

So, that 2-step conversion (sunlight-to-electricity, then electricity-to-heat) means that using PV panels to produce heat is incredibly inefficient. This is because you lose energy with each step.

How To Use Pv Solar Panels in a Greenhouse

It can be difficult to set up solar panels in your greenhouse. They would be too difficult to place on top of your greenhouse as they block sunlight which is what your plants need.

You can set them up in a nearby building or on the ground to solve this problem. To properly distribute heat in your greenhouse, the panels will need to be connected with a power grid.

You will need a number of solar panels depending on the size of your greenhouse. A PV solar panel system typically generates between 10 and 35 kWh per square foot per year. A greenhouse usually consumes 1 kWh of energy per square foot every year.

To heat a greenhouse measuring 10,000 square feet, 27 3×5 feet solar panels will be required. This is a lot of panels for a small area.


Given their inefficiency in generating heat, it is unlikely that PV solar panels will save you money in the long-term. Heating a greenhouse throughout the year can be quite costly, especially during winter.

But, you can still use PV panels to produce electricity. This can be used to power fans, pumps and lighting in your greenhouse.


When it comes to heating your greenhouse, PV solar panels can be quite inefficient. The sun’s energy is converted to electricity which can then be used to produce heat. This multi-step process drastically reduces the amount you can get from the sun.

You will need to purchase and install many panels in order to heat your greenhouse. It takes up a lot of space, which is a problem. This method is also dependent on the sun. However, the sun doesn’t always shine. Cloudy days, which means less solar energy, are more common during the colder months.

You should consider a second method of heating your greenhouse if you are concerned about your plants becoming too cold during the days when your PV solar panels don’t provide enough energy.

Heat Exchangers

What Is A Heat Exchanger?

Heat exchangers heat stored heat and circulate it through the greenhouse when it becomes cold. You can store heat in the soil of your greenhouse.

The heat exchanger heats the soil or other thermal mass, then the stored heat is circulated to heat the greenhouse when it cools.

How To Use A Heat Exchanger For Your Greenhouse

You will need to install pipes beneath the ground to connect to a heat exchanger. These pipes will be used by the heat exchanger fan to draw hot hairs from the greenhouse during the day.

This cools the greenhouse and heats the soil. It also stores heat energy for later use, when it is actually needed.

The heat exchanger system is useful for heating the greenhouse, particularly during winter months. It can also circulate warm air through it. The system is easy to set up and doesn’t usually require professional setup.


This is a great way to heat your greenhouse. All the heat used to heat the greenhouse comes directly from the sun. Natural energy is the best as it benefits the planet and your bank account.

To run the heat exchanger’s fan, you will still require electricity. A PV solar panel, however, can supply the electricity required to run the heat exchanging unit.

A heat exchanger system is less expensive than the hydronic solar hot water heating method. A heat exchanger requires only a fan and pipes while a heating system that uses hydronic heating might need a boiler.


This method depends entirely on the sun.

If it’s a cloudy day, your plants could suffer later that night, since little heat would be stored during the cloudy day.

During colder months, the likelihood of multiple cloudy days is pretty high.

In order to ensure that your plants stay healthy, it’d be best to find a backup method to keep your plants warm.

Other Methods To Heat Your Greenhouse:

Thermal Mass

What is thermal mass? 

The cheapest way to heat your greenhouse is with thermal mass. This requires materials that can store thermal energy such as soil, water and stone. The heat from the heavy material is captured during the day and then released at night.

How To Use Thermal Mass

The easiest way to heat your greenhouse is by using thermal mass. Water barrels are a great way for heat using thermal heat to heat your greenhouse. You can simply stack large water barrels directly in the sunlight. The barrels will absorb the sun’s heat energy during the day.

The greenhouse will heat up when the excess heat from the barrels is released at night. Fish tanks are also a creative way to heat a greenhouse with thermal mass. It might prove beneficial to have your fish tanks in your greenhouse if you are interested in raising fish and plants.

The tanks store heat and let it out at night. This is a great way to heat your greenhouse and provides the ideal place for your fish. To take it further, you can use a heat exchanging unit. This will allow heat to circulate more efficiently once it is released from the thermal mass.

Benefits Of Using Thermal Mass

The simplest and cheapest method to heat a greenhouse is through thermal mass. It is often possible to use materials you already have.

It’s not necessary to install a complex heating system or do additional work. You won’t be charged any extra for utilities. The effectiveness of thermal mass, particularly when used for heating at night, is also impressive.

Soil and water store heat well and plants can be left outside overnight even when the temperature drops below freezing.

Disadvantages Of Using Thermal Mass

However, there are some drawbacks to using thermal mass to heat your greenhouse. The heat doesn’t circulate evenly because there isn’t a fan.

Some plants may receive more heat than others, while some plants may not get enough. The sun is the only thing that makes this method work. The materials will not be able store heat for later use if the sun isn’t shining.

Propane And Gas Heaters

What Are Propane And Gas Heaters?

Gas heaters and propane can be purchased at most stores. They are easily plugged into the wall and this method is a fast way to heat your greenhouse with electricity.

These aren’t actually solar heaters. They’re more like supplemental heating if you use any of these methods and the temperature drops over a prolonged period.

How Efficient Are Propane And Gas Heaters?

Gas heaters and propane are very efficient in heating greenhouses, especially when you are in a pinch. These can be purchased at most hardware stores for about $100 and are very easy to put in. You just need to make a place for them in your greenhouse, and then turn it on.

It is essential to have a vent system installed in your greenhouse if you intend to use this method. Ventilation is essential to prevent carbon monoxide poisoning. Caulk can be used to seal joints around doors or windows to retain heat.

You will be able to save energy and increase the efficiency of your propane heater. This isn’t a natural method of heating your greenhouse. It won’t be as economical as the other methods I have discussed here. This method can be very helpful if all else fails, and your plants know they will need the extra heat.

Space Heaters

You can also use a space heater to keep your greenhouse warm in times of crisis. They are easy to put in and relatively inexpensive to purchase.

Clear a space in the greenhouse, and then plug it in! This method is also safe and easy to use. Although this method is not cheap, it can save you a lot of money. Space heaters can add up to a large utility bill.

This is why you should use it as a backup. Natural energy is better than using it to heat your greenhouse all year.

Frequently Asked Questions:

Do You Need To Heat A Greenhouse In The Winter?

It is important to heat your greenhouse during winter if you live in colder areas. Many plants can’t grow well if it is always cold outside. Your greenhouse should provide the right environment for plants to grow and that means it shouldn’t be too cold. The winter will cause your plants to freeze, and they won’t survive.

How Can I Heat A Small Greenhouse Without Electricity?

You can heat a greenhouse using electricity in many different ways. Thermal mass is the best way to heat your greenhouse without electricity. This is a simple, inexpensive way to heat a greenhouse. You simply need to place water barrels where there is a lot of sun in your greenhouse. Then let them absorb heat and release it later. You can also use a large compost pile to generate heat from the decomposition process if you don’t own any water barrels.

How Do You Insulate A Greenhouse For Winter?

It is essential to insulate a greenhouse so that heat can be stored during winter and night. It is simple to insulate a greenhouse using common materials. To insulate greenhouses, bubble wrap is a common choice. Bubble wrap is a great way to keep your greenhouse warm and doesn’t block sunlight. The bubble wrap can be stapled to the exterior of your greenhouse. Make sure you cover every inch. This is a simple and inexpensive method.

Real Men Sow
Real Men Sow

Hello, I’m Pete and I’m currently based in the west of Scotland, in a small place called Rosneath, where I’m exploring my garden adventures. I personally started gardening around 6 years ago and initially, I started out by growing my favorite fruits and berries, such as strawberries, Raspberries & Gooseberries. Since then I’ve added a lot of vegetables and working closely with my neighbor, it’s been a lot of fun.