Solar Photovoltaic

Emerging PV Technologies

Apart from the solar cell types mentioned above, many research activities are going on to develop new types of cells, aiming to increase the energy conversion efficiency or to reduce the cost. Some examples are given below.

(a) High-concentration PV technology

High concentration PV technology is developed to reduce the amount of PV materials needed for certain power output. It makes use of mirrors or lenses to "concentrate" sunlight onto a much smaller area of active semiconductor PV cell, which produces power at a higher efficiency than at normal solar irradiance level. Actively sun tracking devices are applied in high-concentration PV system to maximize energy production.

An example of a company producing high-concentration PV power generation systems is AMONIX.

Above: Working principle of high concentration PV technology (Source: AMONIX)

(b) SLIVER technology

The SLIVER technology applies the conventional moncrystalline PV technology in an innovative way to save silicon material. Thin and bifacial moncrystalline (100 mm long, 0.5 - 2 mm wide and 40-60 um thick) solar cells, called Slivers, are produced by micromachining and conventional wafer process techniques, which are used to make solar modules. The module utilizes a reflector, and has the slivers cells arranged with space between each cell. As a result, the cells occupy only half of the module surface area and hence the amount of silicon for module production can be reduced.

Above: Working principle of a Sliver module (Source: The Australian National University)

Above: Sliver cells (Source: The Australian National University)

The Sliver technology reduces silicon consumption but demands more processing procedures than conventional solar cell fabrication. Research is being carried out to simplify the fabrication procedures.

(c) Organic/polymer PV technology

The development of organic/polymer PV cells aims to make use of organic materials such as pentacene to replace silicon to produce flexible, light-weight PV cells with lower cost. The main issue with organic/polymer PV cells is low efficiency, and research is being carried out to improve the efficiency.

(d) Microcrystalline and micromorphous cells

Microcrystalline cells are produced by applying new thin-film technology with the deposition process occurring at a temperature between 200 - 500 degrees Celsius to produce crystalline silicon films with very fine grains. In order to improve their efficiency, microcrystalline cells are combined with amorphous silicon in tandem cells to better utilize the solar spectrum and the tandem cell is referred to as micromorph cells.

(e) Hybrid HIT cells

The HIT (Heterojunction with Intrinsic Thin layer) solar cell is made up of a thin crystalline silicon wafer surrounded by ultra-thin amorphous silicon layers that is bonded with an undoped thin film (the intrinsic thin layer) in between. The HIT cells have higher efficiency than conventional crystalline cells, do not suffer from degradation by ageing like amorphous thin film cells. HIT solar cells can also achieve higher energy yield at high temperature, as compared to crystalline solar cells.