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Rooftop solar

Rooftop solar panels turn sunlight into electricity. An inverter converts that electricity into the kind your home uses, so your appliances can run on it while the sun is up.

Any solar electricity you do not use at that moment is normally sent to the grid (exported). Whether solar suits your home depends on your roof, when you use electricity, your electricity plan and local network rules.

What it can do for you

  • Use your own solar electricity during the day instead of buying all of it from the grid.
  • Possibly earn a feed-in credit for electricity you export, depending on your retailer and plan.
  • Lower the emissions associated with the electricity your home uses.

How it works

How rooftop solar electricity flowsSolar panels produce DC electricity. The inverter converts it to AC, capped at the inverter's AC rating. The home uses solar first. Any surplus is exported to the grid, within any export limit; any shortfall is imported from the grid.Solar panelsArray rating: kW DCInverterDC → AC, kW AC capYour homeUses solar firstGridImport / exportDCACSurplus out (export)Shortfall in (import)Output above the inverter's AC rating is clipped.Export limits may curtail surplus.
Technical details
Array size versus inverter size
The array's rating (kW of panels, measured in DC) and the inverter's rating (kW of AC output) are different numbers. Installers often fit more panel capacity than inverter capacity, called oversizing, because panels rarely produce their full rating. How far an array can be oversized depends on the inverter manufacturer's limits, your network's connection rules and the rules of any incentive scheme. There is no single ratio that is right for every home.
Clipping
When an oversized array produces more than the inverter can output, the extra is lost (clipped). A small amount of clipping can be a reasonable trade-off; a lot of clipping wastes generation. A designer can estimate it for your roof.
Export limits
Many networks limit how much a home may export at once. When that limit is reached, the inverter reduces output (curtailment). This affects how much of the generation is actually useful.
Orientation and shading
North-facing panels produce the most over a year in Australia; east and west-facing panels spread production across the morning or afternoon. Shading from trees, chimneys or nearby buildings can reduce output, and some inverter types (micro-inverters or optimisers) reduce the effect of partial shading.
Inverter types
Common household options are a string inverter, micro-inverters on each panel, a string inverter with panel optimisers, and hybrid inverters that can also connect a battery. Each has trade-offs in cost, monitoring detail and shading tolerance.
Summer and winter generation
Generation changes through the year. In Canberra, winter days are shorter and the sun is lower, so a system produces noticeably less than in summer, while heating use (especially in the evening) is usually higher. A design or estimate should look at the whole year, not a single sunny day.

Terms people often mix up

Array size (kW DC) vs inverter size (kW AC)
The panels' combined rating is not the same as the most power the system can deliver to your home. The inverter's AC rating limits the output at any instant.
Gross generation vs self-consumption
Gross generation is everything the panels produce. Self-consumption is the part your home uses directly. The rest is exported or curtailed.
Grid import vs total consumption
Total consumption is all the electricity your home uses. Grid import is the part you still buy after solar. Solar reduces grid import, not your total consumption.
Power (kW) vs energy (kWh)
kW is the rate at any moment; kWh is the amount over time. A system's kW rating says nothing on its own about how many kWh it will produce over a year.

Advantages and limitations

Advantages

  • Advantage: Reduces the electricity you buy from the grid during daylight hours.
  • Advantage: Has no fuel and few moving parts; panels are generally low-maintenance.
  • Advantage: Can be paired with a battery or EV charging later if the system is designed with that in mind.
  • Advantage: Production can be monitored, so you can see what the system is doing.

Limitations

  • Limitation: Produces nothing at night and less on cloudy days and in winter.
  • Limitation: Feed-in credits for exports are often much lower than the price you pay to import, so exported electricity is usually worth less than electricity you use yourself.
  • Limitation: Export limits, shading or a poor roof orientation can reduce the useful output.
  • Limitation: Does not, on its own, keep your power on during a blackout — grid-connected systems shut down for safety unless they are designed for backup.
  • Limitation: Roof repairs or replacement later may require the panels to be removed and refitted.

Financial considerations

1. Quick estimate

Your postcode, yearly use, the solar size and quoted price, and three rates from your bill are enough for a first estimate. Fine-tune everything else afterwards.

Everything is calculated in your browser. Nothing you type here is sent to PlaceNest or anyone else, and you don't need an account. Fields marked as required are needed for the estimate.

Your home & usage

A recent electricity bill has everything this section needs.

Your home's 4-digit postcode — used to estimate sunshine and to find programs for your state or territory.

How would you like to tell us your electricity use?

Your retailer's app or bill may show it; or multiply the bill's 'average daily use' by 365. Main meter only — leave out a separately metered controlled load (e.g. off-peak hot water).

Your solar system & quote

From the installer's quote. Not sure? Use the size you're considering.

The total panel rating (DC) on the quote, e.g. 6.6 kW.

The total on your written quote, including GST, after any discount the installer has already applied.

Your tariff

Copy these from your bill or your retailer's plan details (the “energy fact sheet”), then tell us whether they include GST. We never fill in a price for you.
Your tariff type

Your bill says whether you pay one price all day or different prices at different times.

On your bill as “usage”, “general usage” or “anytime”, in c/kWh.

On your bill as “supply charge” or “daily charge”, in c/day.

What your retailer pays for solar you export (“feed-in tariff”), from your bill or plan. Enter 0 if you have none.

Do the rates you typed include GST?

Many bills print each rate WITHOUT GST and add GST in its own column (look for a “GST” column next to “Amount”). Choose that option and we add 10% to the usage and supply rates — never to the feed-in rate, which has no GST.

PlaceNest assumptions in use — change in Customise: Usage pattern: Most use in the late afternoon and evening · Heating and cooling: No big seasonal change · Panels face: North · Roof tilt: 20° · Shade: No shade · Inverter size: the same as the panel size.

2. Your estimated results

Fill in the quick estimate and press Calculate. Your estimate appears here — it stays in this browser.

3. Customise — detailed settings (optional)

Every setting below already has a value the estimate can use. Open a section to check it against your bill, quote or data sheet — anything you type replaces the PlaceNest assumption or modelling default.

Electricity tariff details (time-of-use times)

Only needed for a time-of-use tariff: choose “Time of use” in the quick estimate, then set your peak, shoulder and off-peak times here. Your usage, supply and feed-in rates and the GST question are in the quick estimate.

Usage pattern
When and how you use electricity changes how much solar or stored energy you use yourself.

This picks an estimated daily pattern. Your real pattern changes how much solar you use yourself. Left on the PlaceNest assumption, we use “most use in the late afternoon and evening”.

Electric heating or air-conditioning shifts use between seasons. Left on the PlaceNest assumption, we use “no big seasonal change”.

e.g. 15 if you'll add electric heating, −10 if you're cutting back. 0 means no change.

Roof orientation & shading
From the installer's design. Left as they are, the PlaceNest assumptions shown are used.

The main roof face. North gets the most sun in Australia. Leave it on the PlaceNest assumption (north) if you're not sure.

Most pitched roofs are about 15–25°; a flat roof is close to 0°. Your installer's design shows it. Leave blank and PlaceNest assumes 20°.

A rough guide only — a site assessment measures real shade. Leave it on the PlaceNest assumption (no shade) if you're not sure.

Panel & inverter details (solar)

The inverter's AC rating on the quote, e.g. 5 kW. Leave blank and PlaceNest assumes the same size as the panels.

Your network may cap how much you can send to the grid (often 5 kW). Leave blank if you don't know.

In kWh per kW per year, if the installer's design gives one (e.g. 1,350). Leave blank to use the official figure for your postcode.

System performance & degradation (solar)
PlaceNest modelling defaults, pre-filled — check the inverter data sheet and the panel performance warranty.

PlaceNest modelling default 97% — check the inverter data sheet.

PlaceNest modelling default 0.5% — check the panel performance warranty.

Future price changes
Nobody knows future prices — try other values and compare.

Nobody knows future prices. PlaceNest modelling default 3% — try other values.

Kept separate from electricity prices: feed-in rates have been falling. PlaceNest modelling default 0% (today's rate held).

Incentive eligibility
Optional. Incentives are only taken off the price when PlaceNest has verified the program and you clearly meet its rules.

Programs have date rules. Leave blank to use today.

If your quote shows the price of small-scale technology certificates (STCs), enter it. PlaceNest never assumes a market price.

Most programs require an accredited installer — ask for their accreditation number.

Only some programs have income limits. It stays in your browser.

Finance, maintenance & comparison period
How the money adds up over the years. A loan changes when you pay — it is financing, not a saving.

PlaceNest modelling default: 15 years.

How much less a dollar in future is worth to you than today. PlaceNest modelling default 5%.

Any servicing cost you expect. 0 if none.

Optional. Enter the terms from a real loan offer.

Government incentives & finance

PlaceNest hasn't verified any current government incentives yet, so none are listed here and none are taken off any PlaceNest estimate. Programs change often: check the official government source, and ask your installer what is already included in the quote.

How PlaceNest checks incentives

Is it likely to suit your home?

It may be worthwhile when

  • You own the home and expect to stay long enough to benefit.
  • You have an unshaded roof area facing north, east or west.
  • Someone is home during the day, or you can shift usage (hot water, laundry, EV charging) into daylight hours.
  • Your electricity use is moderate to high.

It may not be worthwhile when

  • The roof is heavily shaded, small, or due for replacement soon.
  • You rent or expect to move soon and cannot take the benefit with you.
  • Your daytime use is very low and your feed-in credit is low.
  • Your network's export limit is very low and you have no way to use the electricity during the day.
  • A heritage or strata rule prevents installation, or the cost of required electrical upgrades is high.

Common misconceptions

Myth: Solar panels keep the lights on during a blackout.
Reality: Most grid-connected solar systems switch off during an outage to protect line workers. Backup needs specific equipment, usually a battery and a backup-capable inverter, plus suitable wiring.
Myth: A bigger system always means a bigger benefit.
Reality: Beyond the point where most extra generation is exported or curtailed, each extra panel adds less value. The right size depends on your usage pattern and export limits.
Myth: The array's kW rating is the power you will get.
Reality: Real output is usually below the panel rating and is capped by the inverter's AC rating and any export limit.
Myth: Solar removes the electricity bill.
Reality: Most homes still import electricity at night and pay daily supply charges. Solar reduces the amount of grid electricity you buy.

Checklists

Before you buy

  1. Step 1: Check your recent electricity bills or interval data so you know how much you use and when.
  2. Step 2: Get at least two or three written quotes for comparable systems.
  3. Step 3: Confirm the panels and inverter are on the Clean Energy Council approved product lists.
  4. Step 4: Check the installer's accreditation with Solar Accreditation Australia.
  5. Step 5: Compare the array size (kW DC), the inverter size (kW AC) and the expected annual generation in each quote.
  6. Step 6: Ask about the expected export limit for your address and how it affects output.
  7. Step 7: Compare product warranties, workmanship warranty and who you contact if something goes wrong.
  8. Step 8: Ask whether the inverter can connect a battery later, if that matters to you.
  9. Step 9: Read the contract, including payment terms and cooling-off rights, before signing.

At installation

  1. Step 1: The installer confirms the roof condition and any shading on site before installation.
  2. Step 2: Network connection approval is in place before the system is switched on.
  3. Step 3: The system is installed by an accredited installer and inspected or certified as required in your state or territory.
  4. Step 4: You receive a certificate of electrical safety or compliance, the system design, product serial numbers and warranty documents.
  5. Step 5: The installer shows you how to shut the system down safely and how to read the monitoring.
  6. Step 6: Your retailer is told about the new system so your meter and plan can be updated.

Safety

Frequently asked questions

What size system do I need?

It depends on how much electricity you use, when you use it, your roof space and any export limit. A good installer looks at your past bills or interval data and explains why they recommend a size.

Why is my inverter smaller than my panels?

Fitting more panel capacity than inverter capacity (oversizing) is common because panels rarely produce their full rating. The allowed amount depends on the inverter manufacturer, your network and any incentive scheme rules.

Will solar work in Canberra's winter?

Yes, but output is lower in winter because days are shorter and the sun is lower. A system is designed around its output across the whole year.

What is a feed-in tariff?

It is the credit your retailer pays for each kWh your system exports. It is set by your plan, can change, and is often lower than the price you pay to import, which is why using solar yourself is usually worth more than exporting it.

Do I need approval from my network?

Yes. Your installer normally applies to the local network for connection approval, which can set an export limit for your home.

How do I check an installer is accredited?

Ask for their accreditation number and check it with Solar Accreditation Australia, which runs installer and designer accreditation for the national small-scale scheme.

Related topics

Ready to ask for quotes?

Optional: post a request and local providers who offer this service can message you through PlaceNest, or browse providers yourself. Compare several written quotes before deciding.

Request quotes for SolarFind providers for Solar

PlaceNest has not verified this provider's licences, accreditation, insurance or business details. Check what you need directly with the provider before any work.

Sources and review

Draft — pending human review

Not yet reviewed by a person. Programs, products and rules change — check the official source before you decide.

General information only. PlaceNest's energy guides, and any estimates or incentive lists, are general information and estimates — not personalised financial advice, and not a quote. Programs, prices and rules change: check the official sources, and get written quotes from accredited installers before you decide.

PlaceNest guides are general information, not financial advice. Whether solar, a battery or an EV charger pays off depends on your home, usage and prices.

Any incentive or finance details PlaceNest shows come from a reviewed list, each with its official source and the date it was checked; eligibility is decided by each program. See how incentives work and paying for an upgrade.