electricity

Solar Photovoltaic Electricity Creation

The idea and technology of utilising sunlight to create electricity (also called photovoltaics, PV) has been used for many years. Most of us owned calculators, flashlights or garden lights utilising the same technology. Recent advancements in technology and cheaper prices have made photovoltaic systems affordable and interesting for households. We created a calculator based on industry averages for youto find your estimated payback period and future savings.To get to our calculator please click here.

While in the 80s the efficiency of PVs was around 10% it now is between 15-20% on most systems. This increase in efficiency means that less panels are required to achieve the same outcome, lowering the costs significantly. Although 15-20% can certainly be improved upon, PVs are a very attractive option. It is noteworthy that the sun provides more than 10 000 times the amount of energy the entire human race consumes each year.

Photovoltaic panels are becoming more common in New Zealand. Currently, no building consent is required to install photovoltaic panels. What is required is an electrical certificate to ensure the electrical work was done properly. As no building consent is required we do advocate that you carefully research your supplier- it is vitally important that the connection to the roof is done properly and watertight. There is currently in New Zealand no check on this particular part, so please ensure to check out the fixings of your potential supplier beforehand.

How do Solar Photovoltaic panels work?

Sunlight is composed of photons, which are essentially particles of solar energy. All photons hold different amounts of energy which correspond to different wavelengths. When the photons from the sunlight hit the PV cell, some photons get reflected, some pass through and some are absorbed by the PV cell. When the PV cell has absorbed enough photons/ had enough sunlight, electricity can be created (3).

The PV cell is made out of semiconductor material like silicon or germanium, holding electrons. When enough photons/ sunlight hit the semiconductor, the electron held by the semiconductor is freed, leaving a hole. The hole and electron are now able to wander a destined path. The electrons are then collected by thin metal fingers on top of the cell. From there they flow through an external circuit, creating electricity. The electrons are then returning via a small usually aluminium sheet on the back of the solar cell thus creating a circuit.

Advantages of solar or photovoltaic cells:

  • PVs harness the suns free energy- every watt is free of charge to you with no price increases

  • Operating and maintenance costs are almost negligible

  • Option to go off grid supply could help you be self sufficient in case of power outages

  • Due to the fact that PV panels have no moving parts breakages are very rare

  • PVs are easy and fast to install

  • For systems connected to the electricity grid: created electricity can be sold to the power company

Disadvantages of solar or photovoltaic cells:

  • Contrary to logic PVs lose efficiency in peak heat and require a space behind to cool down to improve their efficiency

  • They are an imported product (CO2 emissions) and in our research we could not find any evidence of recycled  materials used (contain metal)

  • PV cells require additional equipment like controllers and inverters to direct electricity (DC) to alternating electricity (AC)

  • The sun is not always out or strong enough to power your home. For people wanting to be self sufficient batteries will be required, making it more expensive

  • PVs require an initial financial outlay, only paying back in time

  • For systems connected to the electricity grid: you will not get any electricity in a power outage from your solar panels

Sources:

(3) U.S. Energy Information Administration, 'Solar explained', 07.10.2019

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