How Much Solar Do I Need?

Sustainable living is gaining quite a lot of traction lately. It’s an understandable trend, considering the state of the environment and the increasing accessibility of info about what it takes for the average person to contribute to sustainability. While there are many aspects involved in sustainable living, one easy fix on a personal level is adding solar power to your home. 

For people who don’t know much about keeping all their power needs met using only solar power, it can be overwhelming to figure out where to start. The first thing you should do when considering how many solar panels you need to run a house is how much power you use. 

What is energy measured in and what do the numbers mean? 

Solar energy is measured in wattage, which is a measurement of power used to determine the rate of energy transfer – or, in layman’s terms, the power it provides for a period of time. One watt is equal to one joule of power per second. Essentially, wattage indicates how much power the panel will provide you. 

To put it into perspective, here are some common household appliances and their approximate power needs:

• Washing machine: 800 watts (w) per cycle
• Hot water heaters: 4 kilowatts (kW) per day
• Oven: 2400w per hour
• Refrigerator: 100–200w per hour or 1kW–2kW per day
• Air conditioner: 3kW–5kW per hour  

How much electricity does a solar panel produce a day? 

To understand how much energy a solar panel produces each day, we first need to consider how much power it gains from the sun. Solar panels have the ability to absorb roughly 20% of the sunlight that hits them and then convert it into usable power for your home. 

Depending on the wattage of your chosen solar panel, the amount of power it produces will change. For example, if you have a 250-watt panel that gets six hours of usable sunlight on any given day, you’ll need to multiply the two. That becomes 250 x 6, which equals 1500Wh or 1.5kWh. That means that one solar panel will be able to provide you with 1.5 kilowatts of energy per day. 

On cloudy days those numbers decrease because only about 10% of the power of the sun is absorbed by solar panels – so the weather also affects how much energy a panel will produce in a day. 

How many solar panels are needed to power an average house in Australia? 

The average household in Australia uses roughly 18–19kW of power per day. That means that one solar panel is not nearly enough to get the job done when it comes to powering the entire household each day. Taking the aforementioned example of a 250-watt solar panel into consideration, this means the average household would need to have at least 19 solar panels to be able to power itself on a sunny day. 

Solar panels up to 400 watts are also available, which would decrease the number you need since you will absorb more power with fewer panels. If you opt for 400 watts and need to power your home up to 19kW, you would likely need only five solar panels. The number of panels is really only important when it comes to space, because as long as you’re getting the appropriate amount of energy, it doesn’t matter how many panels you have. 

Is 5kW solar enough? 

A 5kW system is made up of solar panels that power at a total of 5,000 watts. If each solar panel is 250 watts, that equals 20 solar panels. For the average household in Australia, a 5kW system is enough to power your entire home as long as there are enough sunny days from which to harness the power.

You’ll also need to take into consideration other power needs you may have at different times of the year. For example, during the hot summer months, you may use a lot more power because of air conditioning. This will need to be calculated in advance so that when those months that you use extra power roll around, you aren’t left with less than you need. 

Days where less power is absorbed because of cloud cover will also need to be taken into consideration when choosing the right solar panel system for you. 

What should a 4kW solar system generate per day? 

A smaller system such as 4kW provides only 9.4kWh per day, which is significantly less than the 5kW system. However, not all homes fit into the average box of power used. A 4kWh system can also be used to help offset costs as opposed to replacing your current energy source altogether. 

A 4kW system also changes how many solar panels you will need, so space needs to be taken into consideration as well. Typically, a 4kW system will include 16 panels and can help power a small family home. 

How do I calculate how much solar power I need? 

To calculate how much solar power you need, you’ll have to combine several factors. These include: 

• The size of your home
• Your energy needs
• The space you have available for installation
• How many peak hours of sunlight you get in your area
• The panel wattage you choose 

You’ll then need to multiply your home’s hourly energy requirement by the number of sunlight hours you get. Once you’ve come up with a figure, you can divide it by the panel wattage. To get an idea of how many panels you’ll need for both high-watt and low-watt panels, do the calculation against different panel types to get a range and figure out how much energy it will provide you. 

Once you’ve done all this, you can establish what system is best for you, how many panels you need to get, and the area you’ll need to make available for installation. Alternatively, you can speak to a trusted and qualified professional, who will be able to guide you through the whole process and explain the final quote of the system recommended to you.

Switching from your normal energy provider to solar panels can seem like a tricky process – but with the right information up front, it can actually be really straightforward and fun! In the end, any planning is well worth it to be able to harness natural energy and lower your carbon footprint (and bills)!