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What size solar system do I need and how to evaluate it?

So, you have decided to harvest sunlight to get green solar energy for your home. The first thing you will ask yourself is, what size solar system do I need? This question is crucial, but the answer creates further questions and we are here to answer them. Investing in a renewable energy source like solar for your home requires some prior planning. The maximum electricity output of a solar system is its size or capacity. Let’s evaluate some key aspects first before answering your question.

what-size-solar-system-do-i-need

Is 6.6 kW solar enough?

1-kW solar system produces around 4 kWh of energy on a sunny day whilst the daily usage of an average Australian house is around 20 kWh. This means the 6.6kW capacity solar system that Ultimate Energy Australia offers is more than enough for an average home. The solar system size impacts its upfront cost significantly. But in the long run, solar systems with more power output offer more savings and higher ROI. As you go for more power output in solar, you pay for per kilowatt cost reduces significantly. To wrap things up, What size solar system do I need? You should go for a 5-kW plus solar system capacity for your home. A 6.6 kW solar system bundled with a 5-kW inverter is an excellent choice and a future proof option.

solar panels with bird

Assess home electricity loads for solar system capacity

Knowing your electricity load during the day and its variation in a year is crucial before sizing your solar system.  Kilowatt-hours (kWh) is a primary energy unit to calculate home electric loads.  To give you a better understanding of kWh, let’s use the example of  of an electric heater of 1000 watts (1kW) which is operating for one hour. 

what-size-solar-system-do-i-need

How many solar panels do I need?

If you have no space issues, buying more panels is a wise choice as they come cheaper. More panels will help you produce more power resulting in more offset on electric bills. As a result, the higher feed-in tariff will also save you more money and give you an excellent ROI value. As an example, for the Ultimate Energy Australia 6.6 kW solar system size, you will need Fifteen 440W solar modules. Each module requires 1.7 m², and for t panels, you will need 31 m² of free space.

Determining the size of the solar system you need involves evaluating several factors, including your energy consumption, roof space, budget, and goals for energy savings. Here’s a step-by-step guide to help you evaluate and determine the appropriate solar system size for your needs:

1. Evaluate Your Energy Consumption

  • Review Your Electricity Bills: Look at your electricity bills for the past 12 months to determine your average monthly and annual energy consumption in kilowatt-hours (kWh).
  • Calculate Daily Consumption: Divide your annual consumption by 365 to get your average daily energy usage.

2. Understand Solar Panel Output

  • Average Output: Solar panel output is typically measured in kilowatts (kW). On average, a 1 kW solar system produces about 4 kWh of electricity per day, depending on your location and weather conditions.
  • Location Factor: The amount of sunlight your location receives affects the system’s output. Use solar calculators or tools to estimate the solar potential in your area.

3. Determine System Size

  • Basic Calculation: Divide your average daily energy usage by the average daily output of 1 kW of solar panels in your area to estimate the system size you need.
  • For example, if your daily energy usage is 30 kWh and 1 kW of solar panels produces 4 kWh per day, you would need a 7.5 kW system (30 ÷ 4 = 7.5).

4. Consider Roof Space and Panel Efficiency

  • Roof Space: Check the available roof space for installing solar panels. A typical solar panel is about 1.6 square meters and produces around 300-400 watts.
  • Panel Efficiency: Higher efficiency panels produce more power in less space, so if you have limited roof space, you might need to opt for higher efficiency panels.

5. Assess Your Budget

  • Cost Factors: The cost of solar panels varies based on the type, efficiency, and installation complexity. Consider your budget and financing options when determining the system size.
  • Incentives and Rebates: Look for government incentives, rebates, and feed-in tariffs that can help reduce the overall cost of your solar system.

6. Future Energy Needs

  • Expansion Plans: Consider any future plans that might increase your energy consumption, such as buying an electric vehicle or adding new appliances. It might be wise to install a slightly larger system to accommodate these needs.

7. Consult with a Professional

  • Site Assessment: Get a professional site assessment to evaluate your roof’s condition, shading, orientation, and optimal system size.
  • Quotes and Proposals: Obtain quotes from multiple solar installers to compare system sizes, costs, warranties, and projected energy production.

Example Calculation

  1. Annual Energy Consumption: 10,950 kWh (from electricity bills).
  2. Daily Energy Consumption: 10,950 ÷ 365 = 30 kWh.
  3. Average Daily Solar Output: 1 kW system produces 4 kWh/day.
  4. Required System Size: 30 kWh/day ÷ 4 kWh/day/kW = 7.5 kW.

Therefore, you would need a 7.5 kW solar system to cover your average daily energy consumption.

Additional Tips

  • Monitor Your Usage: Install a monitoring system to track your energy usage and solar production.
  • Energy Efficiency: Implement energy efficiency measures in your home to reduce overall consumption before installing solar panels.

By following these steps, you can accurately determine the size of the solar system you need and make an informed decision that aligns with your energy goals and budget.

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