What to know when buying solar panels

With electricity prices tipped to grow 35% in 2023, you may have considered going green and installing solar systems on your property’s roof.

Find out the key things you need to consider before purchasing solar panels.

How do solar panels work?

Solar panels work by generating electricity when photons (particles of sunlight) knock electrons free from atoms. This flow of electrons is essentially electricity, and solar panels are designed to capture this flow to turn it into useable energy that’s sent to your home and appliances. This process is known as the photovoltaic effect and is the main component behind solar technology.

What size solar panel system do I need?

One of the first features you’ll need to consider is the solar panel system size. When deciding on the system size, consider their main purpose - reducing electricity bills, minimising your carbon footprint, increasing your property value, or whatever else it may be.

You also need to consider your own personal circumstances. Ask yourself the following:

• How much energy do you use?
• How much available roof space do you have?
• How many hours of sunlight/daylight does your property get?

Depending on your answers, you’ll either need to install more panels or a bigger solar system.

To work out your daily household power consumption, check out some of your recent electricity bills - look for 'costs per day' and 'daily usage' and jot down the period it relates to (typically 30 days or 3 months). From there, you can work out how many kilowatt hours you use per day on average.

To work out your solar system size, divide your average daily electricity usage by 3.5. This is because in Australia, one kilowatt of solar panels capacity installed generates 3.5 kilowatt of solar electricity per day. For instance, if your current daily electricity usage is 20 kilowatt hours, the solar system size is 5.7kW.

20 divided by 3.5 = 5.7kW.

As a guide, the typical Australian household uses approximately 20 Kilowatt-Hour (kWh) of energy per day which would require a 5 kW sized system - it would be able to meet most of the daytime power needed. A standard 5kW solar system will normally have about 14-20 panels. However, if you’ve got the extra legroom to afford a bigger system, it can be beneficial to upgrade. The excess electricity you make can go back into the grid and earn you money via feed in tariffs or charge a storage battery.

Solar panel warranties

Always make sure you ask about the guarantees and warranties a manufacturer offers when buying solar panels.

Performance warranty

A performance warranty is a guarantee that the manufacturer will protect you against panels that degrade faster than they should - if/when performance falls below a particular level. Most performance warranties guarantee your panels would produce 80% of their rated output. The industry standard for performance warranties is 25 years.

Manufacturer’s warranty

Meanwhile, the manufacturer’s warranty is usually between 10 and 12 years. It protects you if your system was to underperform due faulty models.

Inverter warranty

The inverter warranty is very important as without the functioning inverter, your solar panels won’t do their job. The inverter works day in, day out at a high voltage which is why it’s the component most likely to fail. Most inverters come with a 5-year warranty.

Installation warranty

Your solar retailer will likely offer you an installation warranty that covers the solar panel installation. They can range anywhere between 12 months to 10 years. Always make sure to ask what’s covered by the installation warranty and who the warranty lies with e.g. the retailer or the sub-contractor.

Getting solar panel quotes

To ensure you’re getting a good deal, it can be beneficial to get multiple quotes from different installers. You can look through business directories, or on solar marketplaces like Solar Choice. These sites let you obtain a quick quote by entering a few general details.

Before you start comparing solar panel quotes, you should have certain information ready including:

• Your monthly electricity consumption
• The type of system you’re after
• A rough budget
• What your roof is made of e.g. colour bond, tiles

It also pays off to read customer reviews and ensure your installer is Clean Energy Council (CEC) accredited.

Is a solar storage battery worth it?

A solar storage battery enables you to store extra unused solar power for later use - generally at night or on low-sunlight days.

While you don’t need to install a battery with your solar power system, it can offer advantages. The first is that you can store extra power you generate instead of sending it back to the grid. You can also set up your system to sell your electricity back to the grid when the battery is fully charged.

A solar storage battery also gives you independence from the grid. For example, if there’s a blackout or an emergency, you’ll have your own backup power.

However, keep in mind that solar batteries represent a significant financial investment with 10 kWh of storage costing around $10,000. While most batteries have a 10 year warranty, the payback period is typically 15 years, which means the battery wouldn’t eventually pay for itself.

What to look for in a solar inverter

A solar inverter is the box on the wall that takes the direct current generated by the solar photovoltaic (PV) panels and converts it to alternating current. Essentially, all the solar power produced by your panels gets taken through the box before being transported to your home for use.

When purchasing a solar inverter, there are a number of things to consider:

• The type of inverter - string, micro, hybrid, or battery.
• Cost - the cost will depend on the type of inverter you choose, size, and brand. However an average cost is between $1,000 and $3,000.
• Warranty - warranties are typically five years, however you should look for warranties of 10+ years to cover the lifespan of the unit.
• The panels and inverter match - your solar panels and inverter must be compatible. For example, if you have a 5kW solar array, then you would install a 5,000 W inverter, plus or minus a small percentage.

Got solar panels or looking to install some soon? Apply for loans.com.au’s Solar Home Loan and get a discount on your home loan when you need it most.

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