Solar Collectors and solar Modules

Solar modules (also referred to as PV modules and solar generators) are used to convert sunlight directly into electricity.

Solar modules

Solar electricity involves a specific type of solar panels (mono crystalline, polycrystalline, thin film…) typically manufactured by large manufacturers as Sharp, Kyocera, Photowatt, BP Solar, or Mitsubishi...

For more information on this type of panels, see:

Solar modules
The number of solar modules
Basics on Solar Electricity: Photovoltaic PV Systems

Solar collectors choice

There are two main types of solar heating collectors:

- flat collectors (glazed and unglazed);
- evacuated-tubes collectors

Other types of solar collectors comprise: ICS (Integrated Solar) and concentrating panels. These last panels are rarely used in solar home applications.

Choosing the type of collector depends largely on climate conditions, price and on the type of application. Below we draw some some rough conclusions about the most suitable solar panels for several solar applications, taking into account the climate, price and type of application.

Solar Flat Unglazed panels

Solar-flat-unglazed collectors are used in swimming pools and simple house space heating (typically, solar air heaters with no heat storage, designed just to heat a room or a small part of the house). Unglazed panels are used in applications demanding low temperatures. They have a wide range of applications in sunny climates, where they can replace more expensive solar collectors.

Image credit: EERE

Solar Air-Flat glazed panels

Solar air-flat glazed collectors are mainly used in solar space heating, and may be tied to forced air systems. They have some advantages over solar liquid-flat panels (they produce heat earlier and later in the day than liquid systems, they do not freeze and the negative consequences of eventual leaks are minimal) but they are also less efficient than liquid collectors, and aren’t as flexible in their applications.

Solar Liquid flat glazed collectors

These panels can be used in solar domestic water heating systems and for central heating (integrated in systems involving forced air systems, radiators or radiant heating). They are a flexible, tested and competitive option. They are by large, at present, the most common type of collectors in moderate and sunny climates.

See, for details: Solar Flat collectors

Evacuated tube collectors

Evacuated tube collectors are a more recent technology than that of flat-plate collectors, and a more promising one. This type of solar collectors can be used in most climates and applications, but despite recent decreases on prices, they still are more expensive than the average flat-panels.

They are the best solution for demanding applications, that is, applications demanding higher water temperatures.

See: Evacuated tube collectors

ICS collectors

ICS (Integrated Collector Storage) or Batch Collectors involve a glazed box and one or more black tanks or tubes in it. They are a cheap alternative in moderate and warm climates, but they have limitations and the solutions based on them lack flexibility.

See: ICS collectors

Concentrating collectors

Concentrating collectors are a rather marginal option in the solar market. They use parabolic and mirrored surfaces to concentrate and get sunlight energy. They are able to generate very high temperatures, and are mainly used on commercial applications. They demand direct sunlight and do not perform well in climates with low levels of direct sunlight.

They are scarcely used on residential applications. They are expensive and involve a large set of demanding requirements and configurations. They are used in large projects and electrical generation. The true alternative concerning solar panels for residential applications is between flat-plate and evacuated-tubes solar collectors.