How Home Solar Power Systems Work

If you’ve been staring at your power bills wondering whether slapping some panels on the roof will save your bacon, you’re not alone. Here’s a bit of the basic stuff on how a solar power system works.

Sunlight In, Power Out: What Solar PV Actually Does

On a typical Aussie roof, solar photovoltaic (PV) panels sit facing north so they cop as much sun as possible over the day. In the southern hemisphere, North is usually the best side of the roof for solar panels.

Each panel is made from special semiconductor materials such as crystalline or monocrystalline silicon. When sunlight hits these materials, they convert light energy directly into electrical energy. This is called the photovoltaic (PV) effect, which is why you’ll hear “PV system” thrown around so much.

That’s very different from solar hot water systems. Hot water panels use the heat from the sun to warm water flowing through tubes. Solar PV uses light to generate electricity. If someone’s trying to sell you “solar” and can’t clearly explain which is which, that’s your first red flag.

From DC to AC: Making Solar Useful in Your Home

Solar panels produce direct current (DC) electricity – the same type you get from a car battery. Most of the electrical appliances in your house run on alternating current (AC), and so does the grid. That’s where the inverter comes in.

Panels: generate DC power
Inverter: converts DC to AC so your appliances and the grid can use it
Switchboard: directs power where it needs to go

Most grid-connect systems are smart enough to:

Use your solar power first, as it’s generated
Automatically draw from the grid when the panels aren’t producing enough (night time, cloudy days, everyone home cooking and washing at once)

If you add batteries into the mix, the picture changes again:

Battery systems: store excess solar during the day to use later, often at night
Hybrid systems: have both a battery bank and a grid connection, giving you backup and flexibility

Batteries are great when they’re sized and installed properly—but with all the rebates and hype, a lot of people are being sold batteries that are too big, too cheap to be decent, or just not configured well. The gear is getting more complex, so having an installer who actually answers their phone later matters more than ever.

How Much Power Can Solar Really Produce?

There are two key ideas people mix up all the time:

Power (W or kW): how fast electricity is being generated right now
Energy (Wh or kWh): the total amount generated over time

Think of it like a tap:

The flow rate (litres per second) is like power in watts
The total bucket filled over an hour is like energy in watt-hours

Panel and System Size

The “size” of a panel is usually its rated capacity in watts under ideal lab conditions, called standard test conditions. For example:

One panel might be rated at 350 W
A typical home system might use 19 x 350 W panels, giving 6,650 W or 6.65 kW under those lab conditions

Panels are commonly around 1 metre wide and 1.7 metres long for homes, with larger sizes used for bigger commercial systems. More efficient panels squeeze more watts out of the same physical size by converting a higher percentage of the incoming sunlight into electricity.

Importantly:

1,000 W = 1 kW
In ideal conditions, 1 kW of panels can produce up to 1 kWh in one hour
In the real world, you don’t live in a lab, so you always get less than the headline “rated” figure

Typical Solar Output Around Australia

Over a full year (summer and winter averaged out), each 1 kW of solar on your roof will usually produce somewhere between 3.5 kWh and 5 kWh of electricity per day, depending on where you live and how well the system is set up.

Typical daily generation per 1 kW of panels, averaged over the year:

Alice Springs: 5.0 kWh
Darwin / Perth: 4.4 kWh
Canberra: 4.3 kWh
Cairns / Adelaide / Brisbane: 4.2 kWh
Sydney: 4.0 kWh
Melbourne: 3.6 kWh
Hobart: 3.5 kWh

Panels will pump out more energy in summer and less in winter, but those numbers give you a decent yearly average.

For context, the average Australian home uses about 18.5 kWh per day, and even a modest 1–2 kW system can knock roughly 24% to 41% off the bill, depending on how and when you use electricity.

Why Your “8 kW System” Never Hits 8 kW

You’ll sometimes hear people complain that their 6.6 kW system “never gets to 6.6 kW” and therefore “isn’t working”. Most of the time, the system is doing exactly what physics says it should – the marketing just never explained the fine print.

Real-world output is reduced by things like:

Climate and weather conditions
Time of day and season
The slope (tilt) of the panels
Which direction they face
Dirt, dust, debris or shade
Losses in the cabling and inverter

Panels also slowly lose performance over the years. This is called degradation, and it’s covered by their performance warranty.

So yes, there are genuine faults sometimes—but more and more often, people call a sparky to “fix” what is actually a billing issue. With feed-in tariffs dropping and electricity plans becoming deliberately confusing, the bit that “isn’t working” is often your power retailer’s business model, not your panels.

Getting the Angle and Direction Right

To get the most out of your solar, the panels should be aimed as squarely at the sun as practical. In Australia, that usually means:

Facing north for maximum annual generation
Tilted roughly around your latitude for grid-connected systems
With at least 10° of tilt so rain can run off and help keep the panels clean

Roof pitches on typical Australian homes are often in the 20° to 30° range, which generally works well. If you’ve got a flat roof, a good installer will add mounting frames to get the tilt right.

In northern Australia, panel mounting is especially critical because of cyclones. A badly secured panel in a big storm doesn’t just “come loose”; it turns into a very expensive, very dangerous frisbee.

Peak Sun Hours and Shading: Where Systems Win or Lose

The amount of useful sunlight your panels receive is often expressed as peak sun hours – essentially the number of hours per day when the sunlight is strong enough to be equivalent to full sun. That’s what determines how much energy your system can generate over a day.

To do well, your roof really wants:

Full sun from about 9 am to 3 pm
As little shade as possible from trees, chimneys, neighbouring buildings or TV antennas
Panels kept reasonably clear of dust and grime

Panels hate shade. Even a small shadow can dramatically cut the output of the entire module because one shaded cell can drag down the cells around it. One tiny bit of tree branch shade can cause a big dent in your generation.

A good accredited installer will calculate expected output based on local peak sun hours and design the layout to avoid shade as much as possible throughout the year.

Panel Quality and What “Tier 1” Really Means

Not all solar panels are created equal, and you don’t want to find that out the hard way after a heatwave, a storm and one long phone queue.

When you’re checking panel quality, look for:

Clean Energy Council (CEC) approved modules
A decent product and performance warranty
Manufacturers with good reviews and technical support based in Australia

You’ll also hear about Tier 1, 2 and 3 manufacturers. The important bit:

Tier rankings are based on things like financial strength, manufacturing scale and automation – not strictly panel quality
A Tier 1 manufacturer can still sell a lower-grade product
So “Tier 1” is a positive sign, but you should still look at reviews for the exact panel model, not just the brand or tier label

And beware the combo of rock-bottom prices and mystery-brand gear. The cheapest quote often comes with the cheapest workmanship, and that’s a problem in a world where solar, batteries and home electrification are getting more complicated, not less.

Why Some Solar Owners Are Suddenly Unhappy

Plenty of early adopters stuck big systems on the roof when feed-in tariffs were generous and panels were smaller. Back then, it wasn’t unusual to see oversized systems that effectively made the household disappear from the retailer’s books for a while.

Over time though:

Feed-in tariffs dropped
Electricity rates went up
Retail offers became more complex and opaque

Now a lot of previously thrilled solar owners are ringing up, insisting their system “isn’t working” when what’s really changed is the bill. The solar might still be generating nicely; it’s just that the financial rules of the game have shifted around it.

At this point, a good solar electrician needs to do more than just check voltages—they need to explain how the electricity market works, what your plan actually does, and how to adjust usage so you’re using as much of your own solar as possible.

Batteries, Builders and the Education Gap

As batteries and “getting off gas” go mainstream, more people who weren’t paying attention in science class are now trying to electrify their homes in a hurry. Unfortunately, that makes them easy pickings for:

Retailers with confusing plans and sneaky fixed charges
Solar and battery sellers pushing systems that are way too big or too cheap to be properly supported
Builders more focused on street appeal than running costs and energy performance

On the building side especially, standards and enforcement often lag behind what’s needed. You end up with:

Roof designs that are hard to work on and not friendly for future solar or upgrades
Poorly installed insulation
HVAC ducting and services outside the insulated envelope, so you’re effectively heating and cooling the shed instead of your living space

All of that matters because a home that’s badly designed or built will chew through more energy, even if you’ve got a good solar system.

How to Get a Solar System That Actually Works for You

If you’re looking at solar (or upgrading an old system), here’s the short version of how to avoid headaches:

Use an accredited installer
They should be across CEC-approved panels, correct tilt/orientation and structural requirements, especially in cyclone-prone regions.
Size the system properly
Base it on your actual daily usage, typical patterns (home during the day or not), and local average generation (kWh per kW per day).

Solar Size Calculator

Respect orientation and shade
Prioritise roof sections that get clean sun roughly 9 am–3 pm, with minimal shading year-round.
Don’t chase the absolute cheapest quote
Really cheap gear and labour often cost more in the long run when something needs fixing and nobody answers the phone.
Look beyond “Tier 1” slogans
Check warranties, support and model-specific reviews, not just the tier rating.
Think about the whole house, not just the roof
Good insulation, sensible layout, decent services and efficient appliances all work together with solar to keep bills down.

If you get those fundamentals right, your solar PV system can quietly churn away for years, cutting bills, buffering you against rising prices and making your home that little bit more future-proof—without you needing a PhD in electrical engineering or a second job reading energy plans.