How Much Power Does A 6kW Solar System Produce Per Day?
In recent years, using a 6kW solar PV system has become significantly common in many households across Australia as it generally meets the typical home energy demand and is likely to reduce your electricity bill.
If you’re thinking to go solar, this system might be an excellent selection for you. However, it is important to take into account how much power your system will produce per day in kilowatt-hours (kWh) to evaluate its feasibility.
In Australia, a 6kW solar system produces power in a range between 18 and 27 kWh per day on average. Although, to obtain more accurate figures, you must consider several factors that affect the daily energy yields of your system, such as its geographic location, panels orientation, tilt angle, shading, and the climate changes during the different yearly seasons.
In this article, we will guide you along these considerations for a better understanding of the power that a 6kW solar system can produce per day.
What Is The Energy Production Of A 6kW System In Australia?
Depending on the state where you live, your 6kW solar system will generate different quantities of energy (kWh) because solar radiation varies throughout the country’s entire surface.
For that matter, we developed for you the quantities of kWh produced by a 6kW solar system referred to 7 major Australian cities: Sydney, Melbourne, Canberra, Perth, Adelaide, and Brisbane.
To do this, we carried out a practical approach by taking advantage of PVwatts tools, which allows you to simulate solar systems and calculate the energy they will produce in a selected location.
In this case, we simulated a 6kW solar system located in each of the previous mentioned cities, obtaining the annual energy production of each one respectively. This provides an average estimation of a 6kW production in such areas, but results could differ for your location depending on particular orientation and shading conditions. The Darwin’s result is shown in figure 1.
Figure 1. PVwatts results for Darwin. Source: PVWatts
As we want the daily rather than the annual energy, we divide this number by 12 and then by 30, hence, we obtain the average energy produced per day by our system for each mentioned state.
Results are shown in figure 2, which is a table that shows the comparison between the different average daily energy productions of the different geographic locations within the country.
Figure 2. Average daily energy production for a 6kW system in different cities of Australia.
Which Factors Affect My 6kW System Production?
Solar Panel Orientation and Optimal Tilt Angle
Since Australia is in the southern hemisphere, north facing your solar panels is considered as the best way to maximize their energy production. Variations for different orientations and tilt angles as well as their average impact on energy production for a particular case in Sydney can be seen below.
Figure 3. Orientation, Angle tilt and efficiency of a solar system in Sydney. Source: Solar Analytics
However, obtaining the maximum possible energy out of your panels isn’t always equal to an efficient production of energy and money savings in your electricity bill. Depending on your energy usage habits, it might be beneficial to shift the direction to the west or east, as we will discuss.
West facing your panels reduces the annual overall energy production by 10 to 20 percent, although, this is a smart move if your home energy consumption occurs mostly during the afternoon. At this time of the day, your solar panels can conveniently absorb more solar radiation when they are oriented to the west.
In addition, pointing to the west your solar panels can save money from your bill since it produces power in the afternoon when the electricity taken from the utility grid is more expensive, as demand peaks usually happen in the afternoon.
For instance, in New South Wales energy units are charged in $0.3648/kWh between 2pm and 8pm, which is more than twice of the price charged in the remaining hours of the day. Moreover, the surplus solar energy produced in this period can be sold to the grid through feed-in tariffs, thus, incentivizing self-consuming your electricity.
On the other hand, for those households with higher power consumption during the morning, facing to the east is more convenient, as panels will take advantage of the morning sunlight to produce the power to supply their early needs. This would also reduce the system’s annual overall energy production compared to facing them towards north.
Additionally, in some cases, the combination of panels orientated in different directions somewhere in-between North, west and east, might be also a good option, and if implemented, it needs to be thoroughly analyzed to measure how much usable power they will produce per day.
Shifting the angle of your panels will result in an energy output variation. The optimal tilt angle will lead to the maximum possible energy production out of your solar system annually.
Although, the ideal angle for your solar panels can vary depending on your solar objectives. For example, if you are seeking to maximize solar generation during winter months, whether for an off grid system or for higher energy consumption levels, you would ideally want to angle your panels at higher than the optimal tilt angle for maximum exposure to the low winter sun.
Figure 4. Different tilt angles for different seasons. Source: Solar Sena
In addition, Australian homes have a roof pitch of 20° to 30° which is considered relatively optimum for maximizing solar power generation. However, the panels can be installed anywhere between 10 to 35 degrees with relatively low efficiency loss. A minimum tilt of 10° is recommended to ensure self-cleaning by rain.
Figure 5. Ideal panel Angles. Source: Solar Calculator
Something that affects dramatically the energy production and performance of your solar system is the shading onto its panels, therefore, considering this factor is essential.
Recall that if a shade is produced over the surfaces of a string of your PV system, the output of the entire string will be reduced substantially as long as the shadow sits there, affecting your overall power production. If there is a separate, unshaded string, however, this string will continue to produce power as per usual.
So, which alternatives do you have for dealing with shaded solar panels?
- Site your solar panel array where there will be no regular shading.
- Use a string inverter that has multiple MPPT inputs.
- Get a system with microinverters or power optimizers.
Figure 6. Power output of solar panels related to different types of inverters when having shading. Source: Solar Reviews
The optimal temperature for solar panels is 25 degrees Celsius. If this value is surpassed, electrons in the panels of your system will get excited, therefore reducing your system´s power output.
This would translate in higher thermal losses during hot summer days, which are not rare in Australia.
To understand how your panels will respond to temperature, you must check their temperature coefficient. In general, most of the coefficients range between -0.25 to -0.50 percent, per degree Celsius.
For example, say that the temperature coefficient is -0.50 percent, this means that the overall efficiency of the solar panel decreases by 0.50 percent for every degree above the optimal temperature for solar panels of 25 degrees Celsius.
How Do The Different Yearly Seasons Affect My Solar Panels Output?
Cloudy weather occurs in colder seasons such as autumn, which happens between March and May, and winter, which goes from June to August. Even though your solar panels will continue to produce at these times, they will produce less electricity, as we discussed in the shading section.
On a partially cloudy day, your solar panel energy losses can rise by 10% to 25%, depending on how frequently the clouds pass over your system. Additionally, high winds can blow dust or debris onto your solar panels, which interfere with their energy production and performance.
Though rain itself usually has a low impact on the energy production solar systems, the rainy clouds will definitely lower your energy production. Occasional rainstorms can be good for your solar system to clean the panels. Layers of dirt or dust that build up on panels can block sunlight and cause a decrease in production.
When considering seasonal solar panel performance, solar panels perform best in spring, which occurs between September and November, and summer, which happens from December to February as sunlight is more available compared to other seasons.
However, in summer, ambient temperature rises, which will also affect your system´s output, as we discussed in the temperature section.
Figure 7. Average monthly outpot for a 6.6kW system in Sydney. Source: Solar Calculator
How Do PV Installation Equipment Affect The Solar Panels Output?
Undoubtedly, using different panels available in the market will result in different power production of your system. Thereby, is important to consider the following characteristics:
- Maximum Power: represents the nominal wattage of the solar panel, measured in Wp or kWp. The higher it is, the more power the panel produces. Nowadays, modern panels have around 200-400Wp.
- Efficiency: is the ratio of energy that is converted into electricity from solar energy radiation. The higher the efficiency is, the more power the panel will produce.
- Type of cell: Whether it is monocrystalline, polycrystalline or amorphous. Variations of these technologies such as bifacial, PERC, or half-cell technology can also have an important impact.
In the figure below, you can check a 2021 review of the most efficient solar panels.
Figure 8.Most Efficient Solar panels review in 2021. Clean Energy Reviews
The inverter is an essential device because it converts the DC power produced by your panels into usable AC power to run your appliances and other loads. There are several characteristics to consider when you want to analyze how much power your inverter will provide, here are some:
- Power Capacity: it needs to be able to handle the maximum power that your panels can generate. That means that if you want a 6kW solar system, a 6kW inverter might be a good option. However, since the output of solar panels varies throughout the day below their maximum peak value, your solar inverter could be rated at up to 25% less than your panel array. For example, a 5kW inverter would work.
- Efficiency: is the ratio of power output in AC to power input in DC, expressed as a percentage. When the inverter is operating, power is lost in the form of heat when the DC-to-AC conversion is done.
The efficiency of an inverter varies with the load. Typically, it will be highest at about two thirds of the inverter’s capacity. This is called its “peak efficiency.” The inverter requires some power just to run itself, so the efficiency of a large inverter will be lower when running very small loads.
We have discussed the average daily production of energy for a 6kW PV solar system in Australia. Although, a more comprehensive analysis is key to size, install and operate correctly your respective 6kW solar system.
What is most important is that we pointed out many factors that affect your solar system, such as, shading, angle tilt, orientation, geographic location, climate and more. Understanding these can give you a better idea on how much power will your system produce and maximize its efficiency.