Solar 101
We all know of solar. It's a very popular topic in the renewable energy sector.
But what is it? How does it work?
I've decided I'd shed some light on the ins and outs of solar, so when you reach a place in life to consider putting a solar system on your roof, this guide will enable you to be much more equipped to know what it is you're even paying for, and how it will help you with your household's energy demand.
The basic equipment for a solar system
First up, in order for you to generate solar power, you need three things:
The sun
Panels that convert the sun's energy to electrical energy
An inverter to convert the generated DC power to usable AC power.
In ins and outs of generating solar power
Photons are packets of energy emitted from the sun. These descend to Earth and reach the photovoltaic panels on your roof.
Photovoltaic panels are made up of cells. These are the dark squares that make up the surface of your solar panel and are usually made from silicon. These cells have two layers: a positive and a negative layer.
When photons reach the panel's surface, they are absorbed by the cell. This absorbed energy causes the electrons in the layer to become free and move downwards through the cell and travel along the connecting cable, flowing through the inverter, and returning through the other cable to the top of the solar cell. This flow of electrons is essentially the flow of electricity that we can harvest, convert, and use in our homes.
The more electrons flowing in the circuit, the more power is generated. So having multiple panels in your solar array increases the flow of electrons, increasing the amount of power generated.
Why do we need to convert the electricity?
Solar panels generate DC - "Direct Current". This is the flow of electrons in ONE direction: electrons are excited and move downwards, through the negative cable and back through the positive cable to be deposited on to the top of the solar panel to start their cycle again.
However, this DC type of electricity is used in applications such as batteries, cellphones, and lights. Lights and cell phone chargers convert AC power from the incoming supply at your switchboard to DC in order to function, and they do this internally (such as LED drivers attached to your household lights, or the little box with the USB port that you plug into your wall socket to charge your phone). The electrical circuits throughout your house transport AC power, or "Alternating Current." In AC power, electrons flow back and forth, hence alternating current. The flow of electrons ("current") is the important aspect for electrical energy, not necessarily the direction of flow.
So, to use the generated solar power in your home, we need an inverter. DC power from your solar array will enter into the inverter. The inverter does magic things to convert the DC power to a perfect sinusoidal form of AC power, which is then injected into your switchboard for use in your home.
Components required for a NZ solar system
To put this altogether and create a functioning, compliant solar system, there are some components that you must have.
These include:
Solar panels,
Mounting and fixing components,
DC-, AC- and UV- rated cabling for power and earthing
DC isolators
AC isolators, and
An inverter.
These components, and other protective equipment, must be compliant in accordance with solar installation standards such as AS/NZS 5033, AS/NZS 4033, and AS/NZS 3000.
Important Note:
Solar installation is considered high-risk electrical work in NZ by the EWRB (Electrical Workers Registration Board) and therefore must be installed and commissioned by a registered electrician, then further inspected by a registered electrical inspector.
So there you have it.
Solar is not a crazy invention only rocket scientists can understand, but it is an amazing invention that has opened up huge opportunities for power generation. Just by connecting a few solar cells together, you can have power instantly at your fingertips anywhere in the world.
Unless it’s nighttime of course. That might make things a bit tricky.
A few key elements to remember:
Solar power is generated by photons hitting a solar cell surface that knocks electrons loose, which flow in a certain direction, creating a flow of current, which we refer to as DC power.
An inverter converts the DC power to AC power for use in your home.
A NZ solar system requires certain components to be compliant with the NZ standards
Solar is considered high-risk electrical work and must be installed and commissioned by a registered electrician, and inspected by a registered inspector.