HOW TO HEAT A GREENHOUSE FOR FREE: According to the basic law of thermodynamics, “Energy cannot be created nor can be destroyed but can be changed from one form to another”. In our case, our goal is to heat the greenhouse so we need some source of energy to convert it into heat. The question is whether that energy source is free or not?  If it is free then we will just have to pay for the equipment’s which converts that energy into heat. The sunlight is free of cost so if we are able to store energy from the sun and use it later to heat the greenhouse during the night then we will achieve our goal. Obviously, it is not completely free there is some initial cost for the solar panels, inverters and the batteries but the running cost is very low.

Nowadays greenhouse has become vital for every gardener and gardening hobbyist. Greenhouse gives you the capability to grow crops and plants offseason which makes it very valuable and special. if you don’t have a greenhouse yet, then think on making one for your self. You can check out this detailed article on “How to make a Greenhouse – Complete Step by step Guide“. We have provided a complete detailed information which will help you in building your own greenhouse.

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how to heat a greenhouse for free

We all built our greenhouses with the sole aim of extending our growing season. As a farmer, you can then have access to perishable plants and vegetables all year round. The world of greenhouses can be so much fun, with the need for greenhouses increasing over the years. This brings about how a farmer can make his greenhouse of high standards. This may also induce the thought of what you need to get or do to make your greenhouse operate more efficiently.

Just like a man, plants need a comfortable environment to grow well. This means that you as a farmer you must be ready to provide their needs. Temperature is a disturbing issue in greenhouses. Farmers still find it difficult to balance the temperature inside the greenhouse day and night. This leads to more efficient ways to keep our beloved plants comfortable. The use of solar panels to heat greenhouses has proven to be more effective over the years than its counterparts. They are energy efficient, and also don’t require electricity. Sunlight is their main source of fuel.

Solar panels are more like a means of generating energy that can be used to produce the required heat that plants needs. Thus, the ways to make the heat available to the plants is needed. There are two major ways to heat a greenhouse using a solar panel, this includes;

  •  Underground Heating using Hot Water
  • Underground Heating using Air

These methods are the new deal in greenhouses. The world of gardening can be very interesting and planting can take place all through the year only if heating is properly done. Heating greenhouses with the energy from solar panels are efficient and have proved its worth. However, this can be expensive at first, But it definitely worth your cash.

Although the use of solar panels to heat greenhouses has been in vogue for years, so many farmers still don’t know how to go about it. They all want to enjoy the benefits of using solar panels where they don’t have to bother about the cost of electricity or other conventional heating methods. This prompts me to share the new ways to which you can heat your greenhouses using the energy generated from the sun.


I know you must have heard that the big bright bulb you see in the sky now and then is fully abundant in energy. This energy is sufficient enough to heat your greenhouse. The sun is a good source of energy and can be tapped. Solar panels are placed on rooftops to get direct sunlight from this big burning bulb. This sunlight is converted to energy and this energy will be used to power heating system. The use of solar panels in greenhouses has been a major talking point. The advantages it brings to the table overwhelm its disadvantages. Therefore, every farmer should make use or employ this unique source of generating heat in their greenhouses.

Solar energy is a renewable energy source, therefore you don’t need to bother about how to fix your energy source when it is about to exhaust. How amazing can that be!  The fact that the energy produced by a solar panel is almost forever, makes it an excellent source of energy. These solar panels also reduce the cost of electricity bill in your greenhouses. The amount of light consumed by your electric heater is much when compared to the amount you are paying for. Solar panels are also easy to maintain compared to other sources of energy in a greenhouse. These panels only need to be cleaned once in a month for proper maintenance. These panels can also last for about 20- 25 years without repairs.

Just like every other equipment used in a greenhouse, solar panels also have some disadvantages that you need to know. This will help your decision-making process, you will know if the solar panels are worth your cash or not. The major problem of this amazing source of heat energy is the initial cost of fixing them. The price of a panel is expensive and not affordable for so many farmers. Although a lot of schemes has been introduced over the years to cut the price, this is still not making any heads way. As said earlier, solar panels feed on the sun. During cloudy days, the efficiency of solar panels reduces due to low light intensity. Therefore this will reduce the energy supplied to your greenhouse.

Are you ready to leave behind that old method of heating your greenhouse, even after all this pros and cons? If yes, you will get all that is needed as you continue to read this article.

 Major types of solar panels used in greenhouses

The Panels used in greenhouses are of different varieties. Each of these panels has its own advantages and disadvantages. Although they all work effectively in a greenhouse, there is still a great need for you to decide on the one you prefer after proper analysis. These panels can be used quite effectively in a greenhouse depending on how well you are able to utilize them. These panels are majorly made from silicon and they are different and ranked according to price and function.

The three major panels used in greenhouses are the monocrystalline solar, which is also known as the single crystalline silicon. These particular types of panels are unique in appearance and can be easily identified from the rest. These panels are dark in appearance and also cylindrical in shape.  They are the most efficient, works better under a low intensity of light and last for about 20- 25 years. The main disadvantage associated with it is the high cost.

The polycrystalline panel is another type of Panels used in greenhouses. Unlike the one said earlier, they are less efficient compared to the first one. These panels are cheaper and can also be a good source of heat energy. But they are not as durable as the Monocrystalline solar cells. Lastly, we have the thin film solar cells. These solar cells are made from several photovoltaic placed on each other. They also provide good heat energy for greenhouses

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 How to use Greenhouse underground hot water heating system

This active heating process is a simple and also an effective way to heat your greenhouse using solar panels. Heat can be produced by pumping hot water into pipes underneath the soil to heat up the soil.  Remember plants care more about the temperature of the soil than the temperature around them. Therefore the heat emitted from the pipes, heat the plants during cold nights. The energy from the solar panels stored in the batteries is used to heat up the water that is pumped into the pipes. These pipes are buried deep down beneath the topsoil to prevent damages during the cultivation and harvest processes. This system makes use of a closed cell foam insulating material. These materials are buried underneath the soil around the perimeter of the greenhouse to prevent heat loss by conduction.

The installation process

  1. First things first, Remove the topsoil at about 16- 24 inches deep.
  2. Lay pipes that are flexible, such pipes should have a high hot water holding capacity.
  3. This pipes should be laid in a coil pattern and in a very large way. Each pack of coils should be spaced seven inches apart from each other.
  4. This large coiled pipes should meet at a particular point, attached to a big drum and a component of the pumping machine underneath as well
  5. This pumping machine will then create a balance of pressure between the tank and the pump. The pump and the water tank must be slightly lower than the coil underground to enable easy drainage of water.
  6. The other end of your coil should be attached to the water heater that is supplied by the combination of pump and tank.
  7. Another thing that should be installed is a standing pipe that will reduce the steam and pressure build up in the system.
  8. The water tank and also the pump should be Fixed in a vault and they should have an indicator that shows what you need to know as you check from time to time.
  9. The water Heated by the energy from the solar panels are transferred to the tanks. This process continues and heats the soil during the night.


The operation process of the system

The main time that plants need heating the most is during the night. This is because the temperature outside the greenhouse drops and in turn it affects the plants.  That is one major part that solar heating system has a part to play. During the daytime when the sunlight is high. These solar panels store energy in batteries to be reused later at night. When the temperature in the greenhouse drops below the normal fixed value, the pumps will switch itself on automatically. This pump will fetch out the water in the coil pipes through the tank. This water will then be passed through the water heater tank where they are Heated. This will then go down the way it came through other pipes into the coil. This pipes will keep giving out heat to the soil and return cool water to the tank for reheating.

This particular process repeats itself until the temperature of the soil is warm enough.  The standpipes remove the excess stem from the system when needed.

How to Use  Greenhouse underground air heating system

This method of heating a greenhouse looks really simple and easy, but it operates more effectively than you can imagine. It uses the mechanism of hot air transfer, thus blowers and other new equipment are required. This particular system makes use of hot air produced by heaters which are powered from solar panels to heat the surroundings and beneath the growing area at almost the same time. Heating a greenhouse with air is quite similar to the first method explained earlier but there are still some differences.

The operation is quite similar to that of the water Heated. The only difference is that the heat media is air and not water.  This methods of using solar to heat greenhouses are effective and highly recommended.


Hope you now find the process used to heat your greenhouse using solar panels simple and comprehensive. You can follow these guidelines and build something good for your plants.

How to heat a greenhouse for free: You cannot heat a greenhouse completely free! you will always have to spend some money initially. The best method is to heat the greenhouse using solar powered panels as the life of these panels are too long so it will keep on heating your greenhouse for quite long


  1. Sincere congratulations! Your passion for plants is admirable and your vision of the vital role of greenhouses in growing locally is absolutely correct. Let’s all do our share in a sustainable green project worldwide for a better future!

  2. I built a 4′ x 4′ compost bunker in my greenhouse, I then got a 1.8mm plastisol coated metal sheet to use as a lid which I built a propogator (mini Greenhouse) on top it also doubles as a potting table etc when I take off the Propogator after all seedlings have been moved on,
    Has we stoke up the Compost bunker with Kitchen waste and Lawn clippings this in turns causes enough heat to Start all my Seeds off and they also get full light to stop them growing straggly like they do when growing on window cills etc, I often get massive crops from Tomato’s… Cucumbers, so much I have to use cane supports and tie at regular intervals to help stop the plants collapsing under the great weights, hope this helps some save on silly prices of parafin and other fuels… Oh nearly forgot, you also end up with a better compost than you’d buy anywhere and the bonus of it not being full of bits of glass and Plastic bags ?. Enjoy.

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