different types of solar panels

Solar Panels for power Generation

Solar panels for power generation (often called solar modules, solar PV panels or photovoltaic panels) are able to transform sunlight into electricity.

They involve three major technologies: the mono-crystalline, the poly-crystalline and the thin film technologies… . There is many hopes about this last type of technology, but by now mono-crystalline and poly-crystalline solar panels are largely dominant.

For more information on these different types of solar panels for power generation, see: Photovoltaic technology

Solar panels for thermal uses

The thermal uses of solar panels include water heating, air-space heating, pool heating and air cooling... All these applications can be accomplished by using two main types of solar heating collectors:

- flat solar panels (glazed and unglazed, air and liquid);
- tube solar panels (evacuated-tube collectors)

There is also a traditional and less-efficient type of solar panels, with a much more limited use: the batch solar panels (or ICS panels).

The use of these different types of solar panels varies with the climate requirements but also with the type of application. Below we draw some broad conclusions about the most suitable solar panels for different solar applications, taking into account the climate conditions and the price.

The different types of flat solar panels

Flat solar panels can be 1) glazed or 2) unglazed.

Glazed panels are more energy-efficient than non-glazed panels, but also slightly more expensive.

Glazed and unglazed panels can use 1) a liquid fluid (often water) or 2) air as the heating medium (the medium that is heated by the sun and that is used to heat the air in our rooms or the water we use in our bathrooms and kitchens). And it is that heating medium that distinguishes flat-air panels from flat-liquid panels.

Solar unglazed panels

Solar unglazed panels are used in applications demanding lower temperatures. They have a wide range of applications in sunny climates, where they can replace other more expensive panels.

Solar-flat-unglazed collectors are used in swimming pools and in air-space heating solutions.

See: Solar air heating systems and solar pool heating.

Image credit: EERE

Solar Air-Flat glazed panels

Solar air-flat glazed collectors are mainly used in solar space heating.

They have some advantages over liquid-flat panels (they can produce hot water earlier and later in the day, they do not freeze, and are much less subjected to the negative impact of possible leaks) but they are also less efficient than liquid collectors.

Solar Liquid flat glazed collectors

Solar liquid flat glazed panels are mostly used in solar water heating systems... They are a flexible, tested and competitive option and by large the most common type of collectors in moderate and sunny climates. They are the most energy-efficient of the different types of flat solar panels, though less efficient than tube solar panels.

See, for details: Flat solar collectors

tube Solar Panels

Tube solar panels are the the newest and most efficient type of solar panels. They can be used in all climates, but despite recent price drops they are still more expensive than flat solar panels.

They are the best solution for applications requiring higher water temperatures. They are also the most efficient solar panels for colder climates.

See: Tube solar panels

Batch Solar Panels

ICS (Integrated Collector Storage) or Batch Solar Panels are the most "primitive" type of solar panels. They are basically a glazed box with a water tank. This type of panels can be used in moderate and warm climates in very simple solutions.

See: Batch solar panels

Concentrating collectors

Concentrating Solar Power (CSP) is a very different way of using the sun, and aims to satisfy large industrial and urban demands.

It involves special and very different types of solar panels - a huge dish/large parabolic reflector, or curved mirrors, or vast fields of mirrors angled to concentrate sunlight onto a single tower at the core of the power plant - to catch the sunlight and to redirect it toward a single point/tower.

Image of a CSP unit: Abengoa Solar

CSP works best in flat desert regions, and requires the power to be transported long distances. Its huge scale requires large amounts of land, and lines to transmit the electricity over huge distances using vulnerable and not at all un-dangerous ultra-high voltage power lines. It also raises problems with dust or sand storms, not to mention problems like the intermittency associated to the lack of sunlight at night (a solution would be to locate the collectors out of the earth, in the space...).