How to Heat a Greenhouse With Solar Panels?

Keeping a greenhouse is beneficial, especially if you want to enjoy a year-round harvest. However, there are some adversaries during the winter months so heating the greenhouse becomes necessary. The good news is, you can prevent having high fuel bills by learning how to heat a greenhouse with solar panels!

Types of Solar Greenhouse Systems

Active Solar Greenhouse System


An active solar greenhouse system works by getting power from the sun and converting it into electrical energy. The energy is captured, stored, and circulated through the use of external devices such as radiators, water pumps, and fans in an active solar greenhouse system. However, passive solar greenhouse systems can utilize solar energy for heating without these devices.

In an active solar system, there are typically two types of solar collectors: photovoltaic (PV) panels and solar thermal collectors. PV panels are devices that convert sunlight directly into electricity. Solar thermal collectors, which can be flat-plate, use a medium like liquid or air to collect and transfer heat. Those that use liquid are called hydronic collectors, while those using air are called air collectors.

One of the benefits of using a solar greenhouse system is that external devices like batteries can store the energy captured from the sun. This stored energy can then be used when sunlight is not available, such as during the night or on cloudy days. This means that while the initial energy source is solar, the system’s ability to store and use this energy later reduces its direct dependence on real-time sunlight.

In terms of its disadvantages, the external devices needed for the solar system may be costly. Furthermore, sustaining the equipment in the active solar system is more expensive than the passive one.

Passive Solar Greenhouse System


Unlike the active solar greenhouse system, a passive solar greenhouse system does not utilize external devices. However, it depends on the structure and construction of the greenhouse. The energy that is collected from the sun is stored in the thermal mass- an object that keeps heat such as rocks, concrete walls and floors, and water tanks.

The principle of the passive solar system involves storing solar energy during the day and releasing it gradually to keep the greenhouse warm, particularly at night. This kind of system is advantageous because the thermal mass easily heats up yet slowly cools down.

Although you don’t have to spend on external devices, you need to have the right glazing and insulation for the greenhouse, so heating would be successful. It also tends to overheat if you live in a warm region.

If you want to learn more about the differences between active solar greenhouse system and passive solar greenhouse system, you can check this 7-minute video:

Materials you need

Prepare these items in advance to facilitate the installation process. You can purchase these items at your nearest hardware store or order them online. As much as possible, look for the items specifically described below.

Solar Panel

If you are planning to construct a 500-watt solar heater, you need to prepare a 500-watt solar panel kit. Different kinds of solar panels are available for greenhouses. Here are some that you can choose from.

The most expensive type of solar panel is the monocrystalline solar panel. In monocrystalline solar panels, unlike polycrystalline ones, the silicon is formed into single crystals, not cut into strips. These thin strips of silicon capture the solar energy and convert it to electricity by undergoing the photovoltaic process.

A polycrystalline solar panel, on the other hand, is made by melting silicon fragments and pouring them into square molds, forming the photovoltaic cells. This is widely used on home solar setups because it is more affordable compared with other solar panels.

Another option that you can choose is the thin-film solar panel. It is lightweight and flexible so it is ideal to use on curved roofs. It is made up of thin photovoltaic sheets placed on top of one another.



There are two options that you have in choosing a heater. You can have a 12-volt DC heating unit or a 250-watt A/C heater. If you prefer a 12-volt DC heating unit, you can directly connect it to the charge controller.

Alternatively, you can use a 250-watt AC heater, which requires a connection through a DC to an AC inverter, not directly through the charge controller. If you prefer this one, you can also use devices with 110 volts in your greenhouse such as light bulbs, fans, and air conditioners.

Batteries Backup

If you want to run a 500-watt heating unit, you can use a 100 Ah Lead Acid battery. One battery can provide you with 4.8 hours of backup for your heating unit. You can add more batteries if you want to increase the backup time for the solar panels.

What to do to


Choose what kind of solar greenhouse system you want

First, you need to decide what kind of solar system applies to your greenhouse. If your greenhouse lacks features like large window panes and thermal mass elements like concrete floors and walls, an active solar greenhouse system might be more appropriate. However, if you have a large place and it is enough to insulate heat, you can choose a passive solar greenhouse system.

Make a plan

After you have chosen what kind of solar greenhouse system you prefer, make a plan. Check the place where you will install the solar panels. If you are planning to put it on the frame, measure if it is large enough to accommodate all of the solar panels. Also, it must be able to support the weight of the panels.

Place supports for the solar panels

To ensure that the solar panels won’t slide off, you must place supports such as handles, latches, and brackets. It is highly recommended that you get a mount rail system. This will help you adjust the position of the panels at any angle you prefer. Don’t hesitate to add support if you think that what you have now is not enough.

Insulate the wires and connect them

You need to insulate the wires first and make them waterproof. To prevent any electric shock, put a ground wire from the mounting hardware that is connected to the ground. After that, carefully connect all the panels’ wires.

Install the photovoltaic system

In installing the photovoltaic system, you must choose a place where it has enough ventilation yet there will be no moisture. You can place it in a large place like your garage. Once you are done installing it, don’t forget to put a protective covering on it.

Connect the AC breaker panel to the inverter

For the last step, connect the AC breaker panel located at your home to the inverter. Connect the DC disconnect switch and the photovoltaic system parts to the photovoltaic wires. Attach the main DC disconnect to the inverter. Once done, test if the solar panel works.

Benefits of Solar Greenhouse Systems


Saves money

You may spend on outlay costs or exterior devices, however, having a solar greenhouse system would save more of your money since you won’t have to pay high electricity bills now and then. Most of the greenhouses with a solar system have zero running costs.

Not affected by the power outage

With a solar system in your greenhouse, you don’t have to mind power outages or power interruptions. The greenhouse will continuously provide warmth to your plants and crops. An overnight power outage is enough to kill the crops, especially if it is cold outside.

Easy to install and operate

You will only need a few hours to install the solar system for your greenhouse. Aside from that, the materials you will need are affordable and easy to operate. If you purchase a solar panel kit, most of the things that you need are included in the package. There is also a manual to guide you.

Environmental friendly

Another benefit of using a solar system is that it is environmentally friendly. It helps in reducing carbon emissions. Aside from that, no toxins are being released that could harm the atmosphere. You can help save the planet by using a solar system for your greenhouse.

Frequently Asked Questions


Is it fine to place the solar panels on the roof of the greenhouse?

You should never install solar panels on the roof of the greenhouse. Remember, plants need direct sunlight to grow.  Solar panels would prevent your plants from receiving the sunlight they need. You can install the solar panels on a building nearby or you can also make a frame for them.

Where is the energy stored?

If it is not connected to a utility grid, the energy from the solar panels is usually stored in batteries. If you need to store more energy, you need to purchase more batteries. However, there are also available batteries that have larger capacities in hardware stores.


With the use of solar panels, you can ensure that your greenhouse has the right amount of heat to keep your plants alive. This method is useful, especially during the winter season. Aside from that, it is affordable and easy to execute as long as you have the right tools.

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