So if you’re wondering about how solar energy can help you save money on your electricity bill and how much electricity, a solar installation can generate over the next year, read further.
This article will give you an indication of what electricity output (and hence, savings) you can expect from a system that we install, and what factors will influence the electricity generated from a system.
According to the Clean Energy Council, the average Australian household consumes 18kWh per day (which can vary based on usage, such as air conditioning or exces lighting.) Residents in Cairns and Townsville can expect a daily electrical output of 21 to 22.7kWh with our 5.1kW solar installation. In short, for the typical household, our systems will reduce most, if not all your electricity bills given bright and sunny days. However, given the cloudy days and individual variations in usage, most of our customers experience a 70% decrease in their household electricity bills.
As an example of the electrical output from the solar installations we offer. These are the average daily production expected from these systems.
| System Size (kW) | Average Daily Production (kWh) |
| 5.1 | 20.7 |
| 6.6 | 27 |
| 8.1 | 33.3 |
| 10.2 | 41.4 |
The estimates of the electrical output is based on a publication from the Clean Energy Council, for a grid connected system and using a simulator from the World Bank Group. Continue reading, to learn more the major factors that will influence your solar installation.
Factors that Influence Electricity Output From a Solar Installation:
1. How your Photovoltaic (PV)/Solar Panels (or modules) are mounted
Fixed Panel Mounting
Fixed mounting is the most economical option and is suitable for installation in Cairns and Townsville, given its latitude relative to the equator. Fixed mounted PV panels face the equator, or in a Northern direction. The angle of inclination, or mounting of PV panels remain fairly constant irrespective of the season.
Most Australian homes have a roof pitches of 15 degrees or 22.5 degrees. As a result, most installers will usually mount solar panels default to these angle angles. However, in our audit and installation, we will advise you on the most efficient tilt angle that is feasible and the options available to you, to ensure that your solar installation will capture the majority of the radiation. For the majority of residents in Cairns and Townsville, a fixed mounting will be sufficient, given our proximity to the equator.
Tracked Panel Mounting
An alternative to the fixed mounting, the tracked mounting allows for adjustment of the PV panel’s tilt angle. This is typically adjusted twice or three times every year to account for the seasonal differences. The variation in the sun can be as much as 30 degrees. In summer the sun can be as much as 15 degrees higher and in the winter, it can be as much as 15 degrees lower. As a result, PV panels installed with the tracked mounting can be adjusted for the sun. This is more costly than the fixed mounting but can increase electrical output by as much as 25%.
Adjustable Panel Mounting
Adjustable mountings track and follow the movement of the sun, throughout the day, as it rises in the East and sets in the West. It also adjusts to coincide with the seasonal movement of the sun. This is a more expensive alternative to the tracked mounting but can increase electrical output by approximately 25% to 30%. Adjustable mountings are more relevant for residents in southern Australia where there is a significant difference between Summer and Winter.
2. Latitude and Sun Intensity
Being based in Cairns and Townsville, we are fortunate to be closer to the equator than most other major Australian cities including Brisbane, Sydney and Hobart. As a result of our proximity to the equator, solar radiation is more intense. The further away from the equator your property or PV panels are installed the less intense incoming radiation will be. NASA has a good explanation of this phenomenon.
Another effect of being closer to the equator is less seasonal variations in daylight length. As a result, residents from Cairns and Townsville will benefit from more intense radiation and consistent daylight. This will give you a better return on your investment.
3. Aerosols
Aerosols are small particles suspended in the air that absorb or reflects solar radiation. They filter solar radiation between the sun and your solar panels which can result in reduced electricity output by your solar installation. This has been reported in countries with a high air pollution such as China and are described as having a comparable effect as cloud cover. Worse of all, NASA scientist, Jan Perlwitz has reported increased aerosol absorption as contributing to more cloud cover.
Based on the most recent publication from the Queensland government on monitoring of air, aerosol and other pollutants will not be a major influence on your solar installation.
4. Elevation
Elevation has a role in electrical output by your solar installation. At higher altitudes, solar radiation travels less. This results in less atmospheric absorption, such as by aerosols and clouds. Hence, more solar radiation will be absorbed by your solar panels.
With the exception of suburbs near Mount Whitfield, such as Stratford, Freshwater and Brinsmead, Cairns has a fairly uniform topography (See Figure 1.) This means that generally, the solar radiation will not be significantly different between one suburb and another.
5. Shading
The immediate surroundings of the site, whether residential or commercial, will have a large influence on whether solar radiation will be absorbed by the PV panels. Hills, trees and neighbouring buildings can absorb incoming solar radiation which significantly reduces the amount captured by the panels for a period of the day. Such an example, can be seen in Figure 2. Different structures will have different absorptions or effects on incoming solar radiation. Because of this, as part of our energy audit, we will show you our most efficient method to capture the greatest amount of solar radiation.
6. Cloud Cover
Incoming clouds have a large impact on the solar radiation that will be captured by your PV panels, as seen in Figure 3. Columbia University reports clouds absorbing or scattering as much as 24% of the incoming radiation.
Our PV panels are designed to capture a wide range of solar radiation and will still operate even in overcast conditions. In some instances, you may notice increased electrical output on a partly cloudy day, higher than what would be expected on a sunny day. This is because sunlight (and radiation) at the edge of clouds can be magnified to temporarily increase electrical output. We assess the risk and will advise in our Energy Audits, whether it is necessary to install additional components to safeguard your solar installation to cope during such events.
7. Relative Humidity
In Cairns, we have a great tropical climate, however, it is also a climate with high relative humidity. Humidity can result in a minimal layer of water vapour on the surface of the PV panel directly facing the sun. As a result, the radiation that is absorbed by the PV panel is reduced due to reflection of the absorption and deflection by the water surface. This is reported to decrease utilization by around 14%. The Tier 1 PV panels we use are specifically designed by their manufacturers for the tropical climate.
8. Heat Accumulation
Heat negatively affects the efficacy of the PV panels and can reduce electrical output by as much as 25%. On a day with dry air temperature of 25°C, it is not uncommon for the panel temperature to reach 45°C. As a result, it is important to have the right design and semiconductors in the PV panels. Our tier 1 panels have a temperature coefficient or PMAX of -0.36%. This means for every degree Celsius above 25°C, the maximum electrical output falls by 0.36%.
In addition to sourcing the most efficient and reliable PV panels, when we design and set up your solar installation, we also consider how we can use airflow to naturally cool the panels. This will improve the performance of the PV panels. One such example we consider, is to raise the panels above the roof or to add a cooling system.
We also source inverters that are designed to tolerate high temperatures in the tropical summers from manufacturers, such as SolarEdge and Fronius. We don’t only use partner with the best brands, we also install these equipment away from direct sunlight, to increase lifespan. Our clients trust our transparency and advice for their long term success and so we have best practice and use the best products.
So, what savings can you expect from a solar installation?
The savings you can expect from a solar installation is largely based on the system size, the type of mounting of your PV panel, the latitude, pollution, elevation, shading, cloud cover, relative humidity and heat build up. But it will also depend on how much electricity you use throughout the day. A property will air conditioning operating around the clock will have a much higher consumption than a property using a fan during the daylight hours.
Previously, the Alliance for Sustainable Energy, from the United States Department of Energy published a model, PV Watts. PV Watts allowed international visitors to estimate the solar radiation at their specific property, impact of different solar installations and the electrical output on a month-by-month basis. It took into account all the variables we discussed earlier however, recent licencing issues with Google Maps, led to the model being temporarily inactivated. You can check if the service is now available by visiting PVWatts.
Alternatively, if you want to find out whether our solar installation will help you reduce electricity costs, fill out the form here. We will promptly contact you, to arrange a no-obligation Energy Audit. This includes a tailored assessment of your goals, specific to your property. We are transparent and will include case studies based on comparable clients, costs, grants, currently available subsidies and loans (where possible and personalised for your situation.)