The sun produces a huge amount of energy that reaches planet earth every year. In the past few centuries, humans have come up with many ways to harness this energy to power our everyday lives.
Both light and heat from the sun are used in solar energy technology. What you’ll generally find on the roofs of New Zealand homes with solar are photovoltaic (PV) panels that convert sunlight into electricity or panels containing tubes that harness the sun’s thermal energy to heat water. Let’s have a closer look into how solar power works.
On this page, you'll learn things like:
- The science behind solar power, explained in plain English
- What is required to store power for later use
- Different ways solar is collected
The process of solar power to usable electricity
The sun is a renewable energy source
Renewable energy is sustainable on the environment and is constantly replenished in nature. Think hydro, wind, tides, geothermal and of course sunlight. As climate change and pollution due to fossil-fuels become an ever-growing concern, the use of renewable energy is increasing. The sun isn’t going to run out of energy any time soon and studies have indicated that we’ve barely started reaching the potential of solar energy.
Research shows that in one hour, the power from the sun that reaches the earth is enough to support the entire world’s power consumption for an entire year. So why aren’t we all using solar power and ending the growing pollution problem? Well, the ability to store all this power, and even collect it are technologies that are still developing. It’s getting better, but we’re still a way off being exclusively sun-powered!
How solar energy generates electricity
There’s actually a few ways that electricity can be generated from the sun, but in many New Zealand residential solar power applications, the type that’s installed are photovoltaic solar panels that use sunlight to produce power. This type of solar energy, often abbreviated as PV, is what we’ll largely focus on in this section. Heat-based solar power referred to as concentrated solar thermal or concentrated solar power (CSP) is another common type of energy from the sun, popular in large plant-scale and water heating operations.
In a PV-based solar power solution:
- Photons of light from the sun hit installed solar panels with semiconductive cells mounted to them.
- The photons excite electrons around the atoms in these cells leading to a ‘charge’.
- A solar power system will then convert the Direct Current (DC)electricity into Alternating Current (AC) electricity - the power that’s appropriate to power our wall plugs, appliances and lighting.
- The transition from DC to useable AC is managed through a Solar Inverter.
- Some systems may have a battery component, enabling power to be stored for later use.
Understanding ‘photovoltaics’
Photovoltaics or ‘PV’ refers to the process of converting light into electricity via material that acts as a semiconductor. This phenomenon, discovered in 1839 by Alexandre-Edmond Becquerel, is known as the ‘photovoltaic effect’.
Simplified, the photovoltaic effect sees light photons ‘knock’ free electrons around atoms in a semiconductor (like a solar panel cell) which, when excited, generates direct current (DC) electricity. Solar Panels harness the photovoltaic effect at scale, by capturing a large amount of light and turning this into a usable quantity of electricity.
Photovoltaic cells are an ongoing area of research associated with solar power technology, with innovation seeking to improve the efficiency, effectiveness, cost and sustainability of the cells produced.
Learn more about Photovoltaics:
- NASA’s explanation of Photovoltaics
- Wikipedia’s article on photovoltaics
How much solar power do I need to collect?
This is going to depend largely on your own power usage habits and needs. If you’re a Powershop customer, you can review your usage here. Understanding more about your day and night time power use can give you a better reference point when you start looking at solar power options.
There are a number of considerations:
- How many kilowatt hours of power a day (daytime and night time) is your home or business using?
- How much roof space do you have available for panels?
- What do you spend on power each month? Does the cost of the solar power system pay for itself in an acceptable period of time from the savings generated?
- Do you want to store solar power for use at night or use solar during sunlight hours and power from the grid at night?
Storing solar energy for later use in a battery
The most solar power generated is when the sun is at its peak around noon. For a home, unless there are stay at home parents or a home office setup, solar power won’t be used when it’s generating at its peak.
For this reason, you may wish to opt for a battery that collects unused solar energy and stores it for use later on (such as night time when the sun is gone).
A battery isn’t mandatory with a PV solar power setup if you are happy to use power from the grid when your solar system isn’t generating enough. But, if you’re aiming to run electricity through solar as much as possible, you’ll want to weigh up the cost of batteries vs. the savings you’ll get. Then you can make a better-informed decision around when storing solar will have paid itself off.
Common terms you may come across in your solar research
Solar Panel
A panel with multiple cells mounted to the surface, designed to capture sunlight and/or heat and turn it into useable electricity or heating.
Solar Inverter
A piece of equipment that transforms the direct current (DC) electricity generated from the solar panel into alternating current (AC) to be fed into the power grid or directly used for everyday power needs such as wall plus and lighting.
AC
Alternating current of electricity - moving in both directions (reversing). This is the type of electricity you have in your home’s wall plugs, lighting and appliances.
DC
Direct current of electricity - moves in one direction. More commonly associated with power lines
Photovoltaics (PV)
Conversion of sunlight into electricity using a semiconductor material.
Concentrated Solar Power (CSP)
Also known as Concentrated Solar Thermal power, CSP concentrates sunlight with mirrors or lenses to create heat that generates electricity via an engine like a steam turbine.
