How Many Solar Panels Does an Average Home Need for Self-Sufficiency
The number of solar panels required for an average home to achieve self-sufficiency varies based on several factors. Understanding these variables is crucial for ensuring that your solar panel system meets your energy needs effectively. This guide breaks down the primary considerations and helps you determine the appropriate size for your solar panel installation.
Factors Determining Solar Panel Capacity
The capacity of solar panels needed for a home is influenced by a range of factors. Firstly, the available space on your roof plays a significant role. Shade and exposure are also critical considerations. East-facing roofs are optimal, followed by south-facing ones, while north-facing roofs are the least favorable due to their lower exposure to sunlight. Proper shading analysis can significantly impact the efficiency of your solar panel system.
The number of people in your home, their energy consumption habits, and the types of appliances and devices used also impact the solar panel capacity. For example, a family with multiple showers and a high-end dishwasher will require more solar panels than a family that uses gas for hot water and heats. Additionally, factors like the age of your air conditioner, its operating temperature setting, and whether you leave lights on when you're not home all play a role. It's important to review your previous 12 months of electricity usage to get an accurate picture of your needs before determining the number of solar panels.
Once you have a good understanding of your energy usage, you can assess the optimal placement of solar panels on your roof. This involves considering the orientation and size of the roof to maximize exposure to sunlight. After establishing the ideal layout, you can focus on purchasing or leasing a system that can be expanded in the future. Both buying and leasing options provide flexibility, allowing for additional panels or batteries to be added as your energy needs grow.
The Role of Energy Storage in Solar Panels
In countries like Australia, the most common solar panel setup includes a 6.6 kW set of panels and a 5 kW inverter, primarily due to the limit of 5 kW that can be fed back into the grid for single-phase house supplies. This 5 kW is often sufficient for many households that have a mix of gas and electric appliances. For homes with solar storage batteries, you may also consider adding more panels to both charge the battery and provide some of the daily load. This additional capacity can be particularly useful during periods of low sunlight or extended cloudy days.
As an example, in sunny southern Australia, we have installed an 8.4 kW solar panel system with a 5 kW inverter and a Powerwall 2 battery. In our two years of operation, our total cost for grid power has been a surprisingly low 175. Given our favorable climate, we have managed to generate a significant surplus of energy, which has saved us money on electricity bills.
Optimizing Your Solar Installation
It's essential to work with a solar installer to determine the optimal size of your solar panel system. Many installers base their recommended installation on the previous year or two's electricity usage. Historically, a "payback" period of 20 years was the norm, but with some subsidies available, this period can be reduced to 6 years. While a standard system might include a 5 kW setup, you can opt for a higher capacity to reduce the payback period.
It's worth noting that the extra cost of a larger system may extend the payback period, but the long-term savings can be significant. For instance, in our case, we initially planned for a 5 kW system but opted for a 7 kW system. While this stretched our payback period, it provided more immediate energy savings. Over the first year, our system generated approximately 40 kWh per sunny summer day and produced an excess of one megawatt of energy over our total usage. While we didn't receive payment for the excess production, our average daily production for the entire year was still 22 kWh, indicating a high level of efficiency.
We anticipate an increase in our energy usage in the future, with upcoming projects such as installing a heat pump and an electric car. These energy-intensive appliances will increase our reliance on renewable energy, making our current system even more crucial.