Researching solar energy, you will doubtless come across the term “photovoltaic” (PV). The term derives its name from the Greek word meaning “light” (phos) and the unit of electrical current, the volt. Photovoltaics is the conversion of energy from sunlight into electric current using a phenomenon known as the photovoltaic effect.

The Photovoltaic Effect

The photovoltaic effect occurs when light strikes a PV cell, which can be made in a number of ways. Modern commercial PV cells use silicon semi-conductors to generate solar energy, but the earliest experimental versions used treated plates of precious metals like platinum and gold.

The photovoltaic solar panel (or solar module) makes use of silicon-based PV cells linked to a network of electrical wires and held in a non-conductive housing. When sunlight strikes the silicon cell, electrons in the silicon begin to flow into the metal wiring of the panel.

This flow of electrons is an electric current, which can be used to power anything from light bulbs to toasters to television sets. While the current from a single photovoltaic cell is small, enough of them arrayed together can generate enough electricity to power a city.

The electric current from the photovoltaic cell is “direct current” or DC. Before it can be used in the home, it must first be run through a Solar Inverter to convert it to “alternating current” (AC), which is standard in all modern electrical systems.

Advantages

• After installation, solar panels are completely green – they generate no greenhouse gas emissions and have no harmful effects on the local environment.
• Photovoltaics are a highly scalable renewable energy source. They can be installed anywhere from the roof of a single house to a huge solar farm.
• Solar cells are becoming more efficient, now exceeding 20% energy capture from sunlight where the first photovoltaic panels had a capture rate of around 4%.
• The cost of solar energy is rapidly falling. Installation costs for solar panels fell 18% in the US between 2016 and 2021, and are expected to fall even more in future.

Disadvantages

• Solar panels still depend on the availability of silicon for the PV cells, and metal for the wiring.
• Since the sun isn’t always shining to a useful level, photovoltaics generally need to be used alongside a battery system to ensure that unused energy can be stored to be made available when needed.
• Silicon harvesting and mining for metals, especially rarer metals like silver, is not always conducted in an environmentally conscious fashion.
• Solar panels are not currently recyclable, and have a useful lifespan of about 10 to 30 years before needing to be replaced.

The future of solar

In future, the solar sector is expected to provide even more of the global power demand, with estimates running as high as a quarter of global electricity needs by 2050 being fulfilled by photovoltaic power.

Residential installations are likely to become more common if costs continue to fall as predicted, making use of the huge and largely untapped surface area of city roofs to generate clean energy for their occupants.

Asia and North America are expected to lead solar efforts, with Asia in particular representing 50% of world solar capacity by itself. Experiments in new solar technologies that are currently being conducted such as photovoltaic windows and roofing shingles are likely to continue to increase the ease of green power generation.