How Do Solar Systems Work?
Want to know how a Solar System works? - It's actually pretty simple.
When solar panels are installed on a roof, the panels collect sunlight and turn it into an electrical current. That current runs through your very own inverter and is then used as energy to power your property.
The Science behind it:
The sunlight collected by the solar panels is turned into an electrical current, called direct current (DC).
The DC is then changed into an alternating current (AC) by a product called an inverter. AC is the type of electricity you use to power your house – to charge your phone or to turn the lights on and off.
The inverter is connected to your meter box so that it can send the electricity to your house or send the surplus power back to your local power grid.
If a solar system produces more power than the household consumes, the excess power is sent back into the main power grid. Electricity companies will actually pay you for this energy.
At the moment, most South-west regions of WA, including Perth, receive a distributed energy buyback scheme buyback rate of 10 cents per kWh between peak times of 3pm and 9pm or 2.5 cents per kWh before 3pm or after 9pm. This is applicable for residential customers with systems 5kW or under.
Does Solar Only Work During the Day?
Yes! However, during the day, your solar panels can produce more than enough electricity to power you right through the night. If you add a battery to your solar system, you can store the excess electricity and use it later during the night. The battery systems are becoming more and more popular with customers preferring to store and use their excess energy.
When the Sun Goes Down: At night when the sun goes down, the solar cells stop producing power. Your home electricity now sources power from your main power grid (the way you get electricity now). Power is charged at the agreed rate (from your selected power company) when the system is not producing.
The two main components of a Solar System
- Solar Inverter
- Solar Panels
Inverters
The role of the inverter is to convert (or invert) the DC energy created from the panels into AC electricity that is usable in households, and then feeds it into your property. The inverter is the hardest working part of your system and is more likely to fail in its 10-15 years. Perth Solar Force recommend using a proven Inverter brand, with a great track record, so you can get the most out of your inverter and solar system.
Inverter size can range from 1.5kW up to 100kW, however the average residential household in WA needs a 3kW – 5kW system, with a 5kw system being the most common. Large scale commercial solar systems use multiple inverters within the one system. What type of inverter depends on each individual customers needs. The Perth Solar Force inverters page outlines the brands of inverters we recommend.
Panels
You may have heard solar systems be referred to as Photovoltaic or PV systems. This is the name for the scientific process that occurs when the solar panels harvest the sunlight and convert it into electricity. This makes solar panels the second essential component of a solar system. Photovoltaic cells make up the panels and energy can be produced directly from them. When sunshine hits the PV cell (in the panels), the UV cells (protons) from the sun charge the electrons in the cell and cause them to create a flow, generating electricity. This is what is called the “Photovoltaic effect”.
Solar panels are classed according to their rated power output (in watts). This rating is the amount of power the solar panel would be expected to produce in 1 peak sun hour. Different geographical locations receive different quantities of average peak sun hours per day. In Australia, the figures range from as low as 5 in Melbourne to 9 in sections of the NT and WA.
Perth sunlight hours range from 3 in June to 9 hours in December. So ideally a 5kW solar system would produce around 12.5kW per day in June, while increasing to approximately 32kW per day in December. Solar panel energy is created through the sunlight, while hot days can make the system less efficient and reduce the output of energy.
Panel Optimisation
The roof angle, orientation and location of your home will impact the efficiency of your system and how much energy your panels can generate. The optimal position for panels is when they are positioned perpendicular to the sun. This means the sun rays hit the PV panels on a 90° angle. North angled rooftops have the best performance and generate the most energy, particularly in southern hemisphere countries like Australia. Perth Solar Force can accurately calculate the optimal position of your panels, your rooftop orientation and angle of the roof to measure the solar output potential of the panels at your property location, utilising a tool called Nearmaps.
In Western Australia, the highest solar energy generated during the day is usually from 10am to 3pm. Read more about Seasons and Panel Efficiency. Panel directions and the type of household’s various orientations generally best suit are given below:
North Facing Panels: North facing panels will produce the highest amount of power/kWs per day. This is because the sun is at its highest and brightest in the middle of the day, which targets the north facing roof and solar panels. This is the best option for people who are at home during the middle of the day or for businesses with high power demands during the middle of the day.
North / North-West Facing Panels: West facing panels generate the most amount of power in the afternoon, because the sun sets in the west and is exposed to the afternoon sun. West facing panels may produce 5-12% less electricity compared to north facing panels, so this is the next best alternative. West facing panels assist households to utilise more solar energy in the afternoons.
North / North-East Facing Panels: East facing panels will produce similar power to West facing panels. The sun rises in the east and is exposed to the morning sun, which will assist households to utilise more solar energy in the morning.
East and West split Panels: Directly east and direct west facing roof may produce around 12% less than north facing panels. The east/west split does have the advantage of producing power all morning on the east side, while doing the same in the afternoon on the west side for most months of the year. This will help with a constant number of panels producing throughout the day from sun rise to sunset instead of a heavy concentration for north panels in the middle of the day.
South Facing Panels: As Australia is so far south of the equator, south facing panels are the least ideal. In the summer time when the sun is directly above your house, south panels may produce just as much power as the north panels. But outside of these months, such as spring, autumn and especially winter, the south panels will more likely produce very little to no power.
