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A Complete Guide To Solar Hot Water System

A solar hot water system is a system that uses the energy of the sun to heat water for domestic or commercial use. These systems heat domestic hot water (DHW) or swimming pool water.

The heat is stored in water heated by an array of solar collectors on the roof or the ground

Solar Hot Water Systems work in homes, schools, hospitals, and other buildings in different parts of the world.

How a Solar Hot Water System Works

An active water heating system
Solar Water Heating System. Image: Emerald Energy Solution

Most solar hot water systems work this way:

The solar collector absorbs the sun’s heat and transfers it to the storage tank. The water in the storage tank heats through the sun’s rays, which then flows into your home through a pipe.

If there is no sunlight for a long time, you can use a backup heater to heat the stored water so it doesn’t freeze.

Main Components of Solar Water Heating System

Solar Collector

The solar collector is the heart of a solar hot water system. It’s a device that absorbs heat from the sun and transfers it to the water in the storage tank. The collector consists of transparent glass or plastic, with a layer of copper tubing inside.

It uses evacuated tube collectors in conjunction with an electric storage tank. These work by using mirrors to concentrate sunlight onto black tubes full of antifreeze fluid. They can’t however, function directly as a refrigerant or indirectly through an expansion valve for heating domestic hot water.

Insulated Storage Tank

The insulated storage tank is a crucial component of any solar hot water system. It is where the hot water is, and it plays an important role in helping keep your folks warm during the cold winter.

The most common insulated storage tanks are made from stainless steel or plastic. You must ensure that your tank can withstand high temperatures regardless of your chosen material.

It prevents damage from occurring due to exposure to heat or freezing conditions during harsh weather seasons such as wintertime.

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Connecting Pipes

Once the solar collector and storage tank are installed, your next task will be connecting the pipes.

Connecting Pipes to a Solar Collector. There are two ways to connect your storage tank to the solar collector. You can use a direct line or an indirect line.

In either case, however, you need to find out what angle your roof faces and exactly how far away it is from your storage tank’s location before you start.

Connecting Pipes from Solar Collector to Storage Tank. If you want a direct connection between the two pieces of equipment, consider using copper pipe instead of PVC. This is because it will last longer due to its higher quality material and a higher tolerance for temperature changes.

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Connecting Pipes from Storage Tank To Backup Heater (Optional). This step isn’t necessary unless you want one connected so that if something goes wrong with either piece of equipment. For example, if there’s no sun on one particular day.

You’ll still have warm water available because it would store heat energy within itself and because heating systems often use multiple fuel sources at once.

Supporting Stand

The stand for a solar panel must be sturdy and level. A good stand will hold the panel at an angle that allows for maximum exposure to sunlight while also providing enough space between it and nearby objects. This prevents damage should it grow or fall into your yard over time.

Since there are numerous ways to make a supporting stand, recommendations are to use metal or wood with a non-toxic paint finish applied correctly. 

The paint you choose should be high quality, durable, and so forth. You’ll want something that will last many years without chipping or fading away!

Backup Heater

A backup heater is a device that helps produce hot water when the solar collector cannot do so. Backup heaters can be either gas or electric.

Gas backup heaters are more expensive than electric ones but have a longer lifespan. They may also be good for remote locations where electricity is not readily available.

How to Fill a Solar Hot Water System

The closed collective unit transfers solar energy from the solar collectors to the storage tank via a heat exchanger system. The closed loop contains a mixture of water and a propylene glycol solution known as ST5.

Which prevents damage to the solar collectors during periods of below zero temperature. Please be aware there are no circumstances under which solutions other than water and ST5 (glycol) can be helpful in a solar water heating system.

To fill the closed loop collector circuit, you will need the following:

  • One bottle of Solar Transfer Fluid (ST5)
  • One 10-liter bucket.
  • 1 small water pump that can generate 300kiloPascals of pressure.
  • 3 clear PVC hoses about 1 meter long
  • 2 metal hose clamps.

Process of Filling a Solar Hot Water System

Connect one end of the second plastic hose to the filler pod and the other end to the discharge connection of your filling pump. 

Connect one end of the third plastic hose to the suction side of your filling pump, then insert the opposite end into the bucket. 

Using the fill pod key, with the AGM 2.5 module, open the fill and drain pods; you need about four turns. Close the pump isolation valve by turning the screwdriver slot into a horizontal position. 

Pump the water flows freely into the bucket from the plastic hose connected to the drain port.

Continue pumping until the water has flowed freely with very few air bubbles.

Close the drain port and continue pumping until the pressure gauge reads between 1 and 1.2 bar, close the port and stop pumping.

Now inspect all connections at the AGM 2.5 module and pump up to and including the collector connections; there must be no leaks.

Fill the tank slowly to avoid water hammer which is a shock wave that results from a sudden change in pressure when opening an outlet valve, like those used for filling your hot water system.

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Fill the tank to about 80% capacity. This will give you extra room for expansion and contraction, which can help prevent damage from thermal shock.

In case of a problem with the system, check these components first: pump, controller/circuit board assembly (or CCA), wiring connections between components and the tank, valves, and fittings, or call a professional to inspect it.

Applications of a Solar Hot Water System

Solar water heaters can work in residential and commercial buildings, homes, schools, offices, hospitals, factories, and hotels. They also help in remote areas without electricity.

Solar water heaters are also used in countries where water is scarce or the temperature is high during summertime, such as Africa and Australia. This is because these areas do not have access to electricity to run their conventional heater.

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Types of Solar Hot Water Systems

There are various options for solar hot water systems. Here’s a breakdown:

  1. Thermosiphon Systems. 

Thermosiphon systems are the simplest and most efficient solar water heating systems. They are also the least expensive to install, making them a good choice for homeowners with limited budgets. 

The system uses a heat-transfer fluid (e.g., antifreeze) to transfer heat from the collector to the storage tank. 

Because they use this simple principle of heat transfer, thermosiphon systems need no pumps or controls—such as valves and relays—to move hot water through pipes under pressure. 

The entire system requires only one pump: an air-operated venting pump that maintains proper ventilation in your attic by removing water vapor generated by condensation inside the collectors.

  1. Direct-Circulation Systems.

The second type of solar hot water system is the direct-circulation system. This system uses a heat exchanger, which transfers heat from the solar collector to the water in your storage tank. 

The advantage of direct-circulation systems is that they are more efficient than thermosiphon systems. Also, less maintenance is required and can be installed on roofs that cannot support enough weight for an active circulation pump (such as some flat roofs).

  1. Drain-Down Systems.

The third type of solar water heater is the drain-down or indirect water heating system. It has two tanks: a smaller one for hot water and a larger one for cold water. 

Hot water is stored in the smaller tank so it can be used as needed; at night, when there is no excess heat from the sun, cold water from your storage tank passes into the larger one, where it’s heated back up again by any residual heat left in your small tank.

The only downside is that drain-down systems aren’t very effective at high temperatures because they tend to lose energy through evaporation over time; however, their efficiency increases dramatically on hot days when there isn’t much evaporation taking place anyways!

  1. Indirect Water-Heating Systems. 

Indirect water-heating systems are another type of solar hot water system. They consist of a collector, an insulated storage tank, and a heat exchanger. The collector can be mounted on the roof or ground, but it’s usually placed on the roof to get maximum exposure to the sun.

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The water is heated by the sun as it passes through your glazing (the glass covering). The hot water then flows into your storage tank, where it’s stored until needed for use inside your home.

For this type of system to work effectively, you must insulate both sides of your storage tank so that heat is transferred efficiently into this area from both sides: one side faces toward direct sunlight while another faces away from direct sunlight (usually toward shaded areas).

  1. Air Systems.

Air systems have a very high heat transfer rate and are much more efficient than other systems. 

This is because they use an air collector to heat water directly in the panel rather than indirectly heat it through a pipe, as with a water system. 

The only downside to an air system is that it has a slightly higher initial cost than other systems because of the increased insulation required for the building envelope and the installation costs associated with labor-intensive ductwork installation.

Air systems require more maintenance than their counterparts because moving parts (the fan) are involved, but this can be offset by having one less part inside your home (no pipes!). 

Because there are no pipes, it’s easier to clean out any issues if you find them early on rather than later when they’ve started causing problems!

Advantages of Installing a Solar Water Heater


Initially, installing a solar hot water system is more costly than other heating systems. However, over time, the savings on electricity bills and reduced consumption will make it cheaper than conventional systems.

Environmentally Friendly

Solar hot water can reduce carbon emissions by up to 75% compared to gas or electric heating. It’s also more environmentally friendly than solar photovoltaic because less power is required to collect the sun’s rays and convert them into heat.

In addition, it is completely organic; no harmful chemicals are used in the manufacturing process, like those involved in fossil fuel-based energy production. This reduces pollution caused by these processes while preserving natural resources like oil supplies worldwide that might run out someday soon!

Disadvantages of Installing a Solar Water Heater

Despite solar water heaters being a great way to reduce your carbon footprint and save money, they have some disadvantages.

First of all, they’re expensive to install. You’ll also be responsible for maintaining the system and ensuring it works properly. 

If your home doesn’t have adequate insulation around the pipes carrying hot water, it will lose a lot of heat through them—an issue that can be costly over time.

Solar hot water systems aren’t suitable for areas with cold climates because they don’t work well below freezing temperatures. If you constantly live in an area with subzero temperatures, installing solar panels may cost more than the energy savings justify.


Solar hot water systems are cost-effective and environmentally friendly. They save you money on your energy bills and reduce your carbon footprint.

The best part? Solar hot water systems can last for decades without fail, meaning you’ll never have to worry about investing in a new one as long as you own your home. 

And with solar hot water systems being reliable and easy to install, installing one will be easy too. The initial investment is high, but the system will save you money in the future. This article has covered everything you need to know about installing a solar hot water system in your home.

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