solar thermal technology explalined

all about solar water heating systems

How they operate, the many varieties, costs, and advantages


We will learn more about the various solar thermal systems, which include solar hot water panels, in this brief guide. We will research their qualities, benefits, and drawbacks while keeping in mind some helpful tips for making the best possible decisions.


The main energy source for the Earth is solar energy. It is a clean, limitless energy source that is constantly accessible, renewable, and has a minimal negative influence on the environment. It may be used to harvest power and heat using sun collectors or photovoltaic panels.


However, as is generally known, we may also use it to produce hot water. Sun thermal heating is the process of converting solar radiation into thermal energy. Therefore, it is feasible to install solar panels that generate hot water in order to minimize the use of boilers. We will discover the key characteristics and functionality of this system in this article.


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

Solar radiation is transformed into thermal energy via solar hot water or solar thermal panels, which are then utilized to generate hot water. The main distinction between photovoltaic panels and solar hot water panels is that the latter are used to generate energy.


The generation of hot water for household use, including the kitchen, shower, bathroom, and washing machine, is one of the primary and most well-liked uses of solar thermal panels.



A photovoltaic cell system should not be confused with a solar system's panels. A photovoltaic system and a solar panel are very different from one another. Through the photovoltaic effect, the latter generates electricity using solar energy.


While a fluid in a solar thermal panel warms water by the sun's heat to provide domestic hot water or water meant to heat a dwelling.


Types of solar water heaters

We have two different systems to pick from:

Systems of both spontaneous and forced circulation

Both are the best option to provide a portion of the yearly home heat demand, which peaks at 70–80%, while having significant disparities from the perspective of the plant. Even complete covering is available throughout the summer.


How do they function?

Let's examine the aforementioned two sorts of systems more closely by investigating how they function.

solar water heating systems with natural circulation

They benefit from the tendency of warm bodies to naturally rise. They are a straightforward and affordable plant option that is great for single people and small families.

The way they function is as follows: the solar liquid, which is made up of water and antifreeze, is heated by the sun's rays before rising naturally to the tank that is positioned horizontally above the solar panels. Here, the liquid transfers its heat to the water in the tank, which is then heated by the sun and enters the home's sanitary plumbing system.


solar hot water panels with forced circulation

The best method for creating large amounts of hot water. Type of system advised for multi-unit buildings, lodging facilities, nursing homes, dining establishments, sports facilities, and gyms...

Thermal collectors have tubes through which a liquid (antifreeze and water) circulates. This liquid warms up when exposed to sunlight. The temperature of the liquid in the panel and the water within the tank are both monitored by a control device in the meanwhile. The control unit activates a pump that pushes the liquid inside the circuit so that it flows through a coil inside the tank if the liquid in the panels is warmer than the water there. Additionally, heat is transferred from the liquid to the tank's water through that coil before it reaches the domestic water circuit of the house.


solar water heaters: benefits

There are several, undeniable benefits to choosing a solar panel system, both economically and environmentally. Let's examine the benefits of a solar hot water panel system together:

significant energy bill savings (up to 35% less energy used for space heating and up to 60% less energy used to heat water). Not to mention any available tax reductions and other government benefits.

no carbon dioxide or greenhouse gas emissions

Home energy efficiency was improved, which resulted in a decrease in fossil fuel usage.

because they may be combined with existing equipment, they are simple to install.

solar water heaters

In the summer, a panel heater's hot water supply

solar water heaters: benefits

There are several, undeniable benefits to choosing a solar panel system, both economically and environmentally. Let's examine the benefits of a solar hot water panel system together:

significant energy bill savings (up to 35% less energy used for space heating and up to 60% less energy used to heat water). Not to mention any available tax reductions and other government benefits.

Zero carbon dioxide and greenhouse gas emissions improved home energy efficiency less reliance on fossil fuels

because they may be combined with existing equipment, they are simple to install.

solar water heaters

A panel's supply of hot water throughout the summer may also be complete.

What volume of hot water do they generate?

It is required to study the product data sheet and refer to its efficiency curve in order to make this judgment. On the label, the following may be seen:


the system's optical efficiency, which is its maximum output when there is no heat loss

the leakage metrics, which, based on the circumstances in which the system functions, show the panel's effectiveness

Solar water heating systems: types

There are two different categories of solar thermal collectors:

vacuum tube with a flat plate

Plate collectors, flat

The absorber has a black surface that faces the sun. It absorbs the most radiation possible and only partially reflects the energy. The energy is subsequently transmitted from the absorber surface to the heat transfer fluid flowing through the tubes below.

Traditional insulation is made of rock wool or polyurethane foam.

This sort of collector is affordable and requires little upkeep and repair. It can support or provide hot water for underfloor heating in low-temperature systems.


solar collectors using vacuum tubes

Vacuum tube collectors exploit the superior insulating properties of vacuum while still operating on the same principles as flat-plate collectors. As a result, heat losses are almost eliminated thanks to the vacuum inside the glass tube. Finally, for the same output, vacuum tube collectors offer greater efficiency, outstanding performance, and also need less roof area. Additionally, they can be applied to surfaces that are not facing south.


How many solar water heaters are there?

There are no exact guidelines. Your desired degree of comfort will determine a lot of things.

It is possible to enlarge the system, but only within specific bounds, as doing so runs the danger of creating an excessively hot solar circuit, which might lead to damage.


solar collectors using vacuum tubes

Vacuum tube collectors exploit the superior insulating properties of vacuum while still operating on the same principles as flat-plate collectors. As a result, heat losses are almost eliminated thanks to the vacuum inside the glass tube. Finally, for the same output, vacuum tube collectors offer greater efficiency, outstanding performance, and also need less roof area. Additionally, they can be applied to surfaces that are not facing south.


How many solar water heaters are there?

There are no exact guidelines. Your desired degree of comfort will determine a lot of things.

It is possible to enlarge the system, but only within specific bounds, as doing so runs the danger of creating an excessively hot solar circuit, which might lead to damage.


the roof's pitch and direction

the vicinity of the home

the climate's cyclical nature

Knowing that a natural circulation system can cost somewhere between 500 and 900 euros per square meter can help you obtain a broad notion of costs. A forced circulation system, on the other hand, might cost between 1,000 and 1,100 euros per square meter.

solar panels for heating and hot water


The heated fluid inside the collectors can be added to the heating system in addition to providing household hot water. This approach offers possibilities for extra savings while providing an intriguing support for the functioning of the heating system.

Due to solar heating support, the heating unit may stay off even at mild temperatures.