While selling the flat plate solar collectors, I always meet clients who ask questions like: how much electricity can your collector generate? Your collector looks the same as PV, what’s the difference? Is your product an anti-dumping product? etc. I found that most retail clients don’t know how to distinguish between two products, and don’t know how to choose the right one for their home. That’s where this article comes from.
The solar thermal collector and solar PV panel have a very similar appearance, so users often confuse the two products, but they are two completely different products indeed. In a nutshell, the solar thermal collector converts solar energy into heat energy, which is used to heat water or space. They can be essentially heat exchangers. In contrast, solar PV panel converts solar energy into electricity, which is used to generate electricity. Let’s see the difference between the two products from the technique, working principle, application scope, etc.
Solar Thermal Collectors
Solar thermal collectors capture the solar radiation to heat water. There are two different types of solar collectors, one is the flat plate solar collector, which looks very similar to a PV panel, and the other is the evacuated tube/ vacuum tube collector.
In this article, the solar thermal collectors I refer to as the flat plate solar collector, they are usually consisted of :
- Glazing cover– a transparent cover made of either glass or plastic to protect the absorber plate
- Absorber– it can be a sheet of copper or aluminum with blue sputtering coating or black chrome coating, and combinate with copper tube grids, it absorbs the solar radiation and transfers the heat to the water or heat transfer fluid in the grids. It’s considered the “heart” of the collector.
- Aluminum casing– it’s used to protect the components and hold them securely in place.
- Insulation and Back sheet– Improve thermal performance and reduce heat loss.
Solar Photovoltaics Panels (Solar PV Panels)
The solar PV panel is based on the photovoltaic effect, by which a photon (the basic unit of light) impacting a surface made of a special material generates the release of an electron. There are three main types of solar PV panels on the market, monocrystalline, Polycrystalline, and Thin-film solar cells. The difference between them is the level of efficiency and flexibility. Below are the components that comprise a solar PV panel:
- Solar photovoltaic cells – PV cells are made of a layer or two of a semiconducting material, typically silicon. When sun rays hit the cell, it generates an electric field. The more intense the light is, the greater the flow of electricity.
- The cells are wired together to form a solar power panel, also called a module
- The panels send the generated direct current (DC) to an inverter – a separate piece of equipment – which turns it into alternating current (AC)
- Junction box and connectors – small enclosure located behind the panel to attach the cables necessary to interconnect the panels.
- Tempered glass – designed to resist mechanical loads and extreme temperature changes while protecting the PV cells from the weather and debris.
- Aluminum frame – protects the edge of the laminate section that holds the cells. The frame enables the solar panel to be mounted securely into position.
- EVA film – transparent ethylene vinyl acetate (EVA) encapsulates the cells.
- Back sheet – a barrier against moisture while providing mechanical protection and electrical insulation.
How does Solar Thermal Collector work?
Solar thermal collectors are considered the main part of the solar water heating system. The collectors usually have been installed on the roof, the absorbers collect sunlight and heat up the fluid in the copper tubes, and the fluid transports the heat to a cylinder where it is ready for use. The fluid can be water or glycal, it depends on the different ambient temperature and water quality conditions.
How does a Solar PV panel work?
Made from two layers of a semi-conducting material and silicon, solar PV panels are able to produce an electric field when exposed to sunlight. When the sun connects to the surface of the Solar PV, a small voltage of electricity is created. This electricity direct current (DC) travels to an inverter, which transforms it into AC (alternating current). You might recognize AC as the ‘language’ of many of your home appliances. Electricity is diverted to your fuse box and onto these appliances for use around the house, or if not needed, re-routed to the electric grid.
Below is a schematic for both systems which can help you understand the principle.
Different application scope
The main purpose of solar thermal collectors is to heat water or space, it can be widely used for residential, commercial, and pool heating systems.
Solar photoelectricity product includes Photovoltaic plants, Solar road lamps, lawn lanterns, court lamps, beacon lights, farm insecticidal lamps, signal lamps, traffic warning lights, solar Information Displays, and so on.
Different HS codes
As an importer or exporter, you may also want to know the HS code for both products, as it will cause different tariffs. The HS Code for the solar thermal collector is 84199010, while for Solar PV panels, they are always under the HS codes 85414011, 85414019, and 70071900. It should pay attention that solar PV panels are considered antidumping in many countries.
A PV System and a Solar Thermal System are both fantastic renewable and green energy choices that have economic benefits as well. If you want to get more free hot water, then perhaps the solar thermal system is best. But if you would like to turn your electricity bill into a possible source of income, then you’d better to choose a solar PV system. Both systems benefit your various utility expenses and will save you money in the long term. In recent years, to maximize the use of solar energy, there’s a combinate system developed, this panel calls the TVP panel, which can heat water and generate electricity as well. This is another topic that we can discuss later.