One of the most common questions people have before investing in solar is how many panels they need.
The simplest way to find this out is to ask an expert installer. They will likely conduct a consultation and provide you with a quote based on your energy needs.
As a rough guide, a house with one or two people will likely need a 1.5kW system. A household with up to three people and a few fancy appliances may need 3kW. While a big family will probably need a 5kW system.
But this all depends on the type and number of appliances you use, the expected output of the panels, where the panels are located, and how they are oriented on the roof. With so many variables, it really is worth consulting an expert solar installer to determine how many panels you need.
Alternatively, if you’re mathematically inclined, you can attempt the estimate yourself. To do this, you need to figure out your average daily use of power.
You can probably find this on your most recent bill. If it only shows your yearly use, simply divide this number by 365 to get a daily average. For example, let’s assume your yearly use is 5,000 kilowatt hours (kWh). Divide this by 365 to get a 13.7 kWh daily average.
Whatever way you use to determine your needs, it’s best to build in a buffer. Solar panels don’t work at 100 percent efficiency. There will be times when their output is reduced. So add a little extra – say another 25 percent. To do this, multiply the daily average by 1.25. Using the example above, this comes to 17.1 kWh.
You also need to take into account the amount of sunshine your home receives. While Australia is mostly sunny – and receives more solar energy than any other continent – some parts are shadier than others. Ask your installer or local solar authority about the amount of sunlight you can expect to receive on your roof.
You then need to divide your daily average by the number of daylight hours. This figure will tell you how many kilowatts are needed each hour by your panels to absorb solar energy. Let’s assume your suburb receives 6 hours of daylight. Divide 17.1 by 6 to get 2.85 kW needed every hour. Times that by 1,000 to convert the sum into 2,854 watts.
These system sizes allowed you to run your home on solar as much as possible while minimising the wasted electricity sent back to the grid.
We asked Stephen Jenkins, a homeowner on Central Coast and proud solar owner since May 2017 to share his energy bills with us before and after installing a 5kW solar system. Some data on the bills below have been blurred due to privacy reasons.
|Bill from 2017||Bill from 2018|
This is frustrating for many people, especially if you have a full-time job. You end up getting free energy during the day, but you aren’t able to use it.
Thankfully, these limitations have now been overcome by modern solar battery storage technology. Homeowners can now save money no matter when they use their appliances
Let me explain...
Although solar battery systems have been around for years, they were cumbersome, expensive and a poor investment. Unless you lived in the remote outback without a grid connection, they didn't’ make sense.
But new technology breakthroughs have changed all that…
The newest batteries can economically store the electricity generated by solar panels during the day… so that you can still benefit from free energy even if you are only at home after dark.
Here’s how they work...
At night, you can run your dishwasher, watch TV, or charge your phone without paying for power.
The current leader in the solar storage market is the Tesla Powerwall 2.
The Tesla Powerwall 2 has twice the storage capacity of the original Powerwall - 13.2kWh. This is enough to power most homes after dark, so you can cut your bill significantly.
Not only that, the Tesla Powerwall 2 is beautifully designed. It is streamlined, sleek and stylish. Plus, it is rated for indoor or outdoor use in the harsh Australian climate.
It is also very safe. There are no live wires or unsightly vents - and the lithium ion battery requires minimum maintenance.
You can even monitor your electricity usage from your iPhone or Android device!
Plus, if you need additional capacity, you can connect nine Tesla Powerwall 2 units together. This is great if you want to power your home during blackouts or on overcast days.
The amount of money you can save will depend on your actual individual circumstances.
However, case studies suggest you could reduce your mains grid electricity consumption by as much as 80% with a solar + battery system. This is based on standard system installation in a state capital.
The upfront costs are variable too, but it is possible to get the system installed for as little as $35 a week on an interest free loan.
These savings are based on existing government incentives, which may disappear at any time, so if you are thinking about solar storage, don’t delay.