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Solar & Battery System Advisor

Model · Simulate · Validate — runs entirely in your browser

Simple Expert
System setup
Configure your location, solar system, and household consumption

Location & solar PV system

10 kW
⚙ Advanced settings
80%

Household consumption

25 kWh/day

Your current electricity costs

Enter your current bill to anchor the ROI baseline. The model compares what you pay now versus what you'd pay after solar — the difference is your annual saving.

Solar generation preview

Solar generation (kWh) Household usage (kWh)
⭐ Save recommendation
Assumptions: Solar modelled using location-specific GHI data × system efficiency × orientation factor. Default values: daytime load = 40% of daily usage, battery usable capacity = 90%, EV efficiency = 6 km/kWh, retail rate = $0.30/kWh, battery charge rate = 0.5C, smart EV charger rate = 3.6 kW, validation tolerances ±10%/±20%. All of these can be customised on the Assumptions page. Australian free power window: 11 am–2 pm modelled as ~45% of daily solar and ~30% of daytime load; free grid capped at 24 kWh/day. This tool is for indicative planning only — consult a certified installer for a formal proposal.
Happy with your setup? View your energy results.
EV charging
Configure electric vehicle demand and charging patterns

EV configuration

65 kWh
40 km
5 days/wk
7.2 kW
⚙ Advanced settings
0 $/mo

EV demand summary

EV demand (kWh/day) Household demand (kWh/day)
EV settings are factored into your energy simulation.
Results & charts
Annual energy flow simulation using the recommended battery size
🔍 Want deeper analysis? Switch to Expert mode to see monthly energy flow charts, seasonal performance, battery comparison, and inverter sizing.
📊 Save this result

Monthly energy flows (daily average kWh)

Solar generation Direct solar use Battery discharge Paid grid import

Self-sufficiency & battery utilisation by month (%)

Self-sufficiency % Self-consumption % Battery state of charge %

Seasonal performance summary

Ready to explore further?
Battery simulator
Test any battery size and see real performance impacts
🔋 Save this comparison

Custom battery size

10 kWh

Battery size comparison — monthly self-sufficiency

Recommended Custom

Battery utilisation — monthly average state of charge

Recommended Custom

7-day battery charge profile

See how each battery charges and discharges across a typical week for the selected month. Set the starting charge level to explore how quickly each battery settles into its natural daily cycle.

50%
Batteries to compare

Each day shows 4 phases: pre-dawn (after overnight EV) → solar peak → evening (post-VPP dispatch) → midnight (after household draw). Y-axis is % of usable capacity.

Virtual Power Plant (VPP) modelling

A VPP programme lets your retailer dispatch your battery to the grid during peak demand events (typically 4–8 pm). You earn a peak export rate for the energy dispatched. Model how VPP participation affects your battery charge cycle and what size battery you need to participate reliably.

Done comparing? Head back or validate a quote.
Installer proposal checker
Compare quotes, model ROI with real assumptions, and get tailored questions for your installer meeting
💡 You're in Simple mode. To validate installer claim details (generation, self-consumption, grid independence) switch to Expert mode.

ROI components

Select which savings to include in the payback, NPV, and IRR calculations.

Grid savingsRetail electricity cost avoided
FiT revenueFeed-in tariff export income

How the ROI is calculated

➕ Add installer proposal

⚙ Installer claims & validation fields

Questions to ask your installer

These questions are tailored to your current system configuration and update automatically as you change settings.

Assumptions & settings
Customise the values used throughout all calculations. Changes take effect immediately.

Visible sections

System setupAlways visible
EV chargingElectric vehicle demand
Inverter sizingAppliance load calculator
Results & chartsEnergy flow simulation
Battery simulatorCustom battery sizing
Provider adviceTariff & plan guide
Saved snapshotsYour saved comparisons
Installer checkValidate quotes
Hiding a section removes it from the navigation. It can be re-enabled at any time here.

Electricity tariffs & financial assumptions

0.30 $/kWh
Used to estimate savings from free power and solar self-consumption. Average Australian rate ~$0.28–0.35/kWh.
0.06 $/kWh
Rate paid for excess solar exported to the grid. Typical Australian FiT is $0.05–0.10/kWh.
3.0 %/yr
Used in ROI projections. Australian electricity prices have risen ~3–5%/yr historically. Higher rates improve the payback case.
0.50 %/yr
Annual reduction in panel output. Quality panels degrade 0.3–0.7%/yr. After 25 years at 0.5%/yr, output is ~88% of original.
5.0 %/yr
Used to calculate Net Present Value of future savings. A 5% rate is a common real-return benchmark. Use your mortgage rate or opportunity cost of capital.
▶ Advanced settings Battery · Load profile · Free power · Inverter & EV · Validation tolerances

Battery assumptions

90%
Percentage of nameplate capacity that can actually be used. Most lithium batteries are 90–95%. Older or degraded batteries may be lower.
1.6×
A battery larger than this multiple of the recommended size is flagged as potentially oversized in the Battery simulator.

Load profile

40%
Proportion of daily electricity use during daylight hours (~7 am–7 pm). Households with people at home during the day typically use 50–60%.
60%
Automatically calculated as 100% minus the daytime fraction.

EV assumptions

6 km/kWh
How far the EV travels per kWh of battery. Small/efficient EVs: 7–9 km/kWh. SUVs/trucks: 3–5 km/kWh. Default 6 is a typical mid-size sedan.
2.00 $/L
The petrol or diesel price for the car the EV is replacing. Used to calculate annual fuel savings in ROI projections. Australian average ~$1.80–$2.20/L.
10.0 L/100km
Fuel consumption of the petrol/diesel car being replaced. Small cars: 6–9 L/100km. SUVs/4WDs: 10–15 L/100km. Default 10 is a typical family car.
3.0 %/yr
Expected annual increase in fuel prices. Petrol prices are volatile — 3% is a conservative long-run average. Higher rates make the EV fuel saving case stronger over time.

Free power window

24 kWh
Maximum free grid energy available per day during the 11 am–2 pm window.
45%
Estimated share of daily solar generation that occurs between 11 am and 2 pm. This is higher than the 3/10 time fraction because solar peaks at midday.
30%
Share of daytime consumption that occurs during the 11 am–2 pm window. Proportional to the 3-hour window out of ~10 daylight hours.

Inverter & EV charging

0.5 C
The maximum continuous charge rate as a fraction of battery capacity. 0.5C means a 10 kWh battery charges at up to 5 kW. Most residential lithium batteries support 0.5C–1.0C. Used in inverter free-window battery sizing.
3.6 kW
When an EV charger is set to "smart" mode (solar headroom-filling), it throttles to this rate rather than charging at full speed. Typical smart chargers operate at 1.4–3.6 kW in headroom-fill mode. Used in inverter sizing for smart charger scenarios.

Installer validation tolerances

10%
Claims that exceed modelled values by more than this percentage are flagged as "Optimistic".
20%
Claims exceeding modelled values by more than this percentage are flagged as "Unrealistic".
About these values: All assumptions are simplified models intended for indicative planning. Real-world performance depends on your specific equipment, local weather patterns, household occupancy, network tariff structure, and battery degradation over time. Consult a certified solar installer and your electricity retailer for accurate figures tailored to your situation.

Installed app — keeping it up to date

If you have added this app to your home screen (iOS, Android, or desktop), updates are delivered automatically via the service worker. Here is how it works and what to do if you want to force an update.

How automatic updates work
Each time you open the app while online, the service worker silently checks the server for a new version in the background. If a new version is found, it downloads it — and the next time you fully close and reopen the app, the new version activates automatically. You will see an ⬆ Update available banner at the bottom of the screen; tap Reload to apply it immediately without waiting.
Force an update now
If the update banner has appeared, tap Reload. If it has not appeared yet, try one of the following:
1 Close the app fully — on mobile, swipe it away from the app switcher. On desktop, close all tabs running the app. Reopen it. The service worker activates any downloaded update on the next launch.
2 Hard reload — on desktop, press Ctrl+Shift+R (Windows/Linux) or Cmd+Shift+R (Mac) to bypass the cache and reload from the server.
3 Clear the app cache (iOS) — go to Settings → Safari → Advanced → Website Data, find the app's domain, and tap Delete. Then reopen the app.
4 Clear the app cache (Android) — go to Settings → Apps → your browser → Storage → Clear Cache. Or in Chrome, go to Settings → Site settings → find the app → Clear & reset.
5 Uninstall and reinstall — remove the icon from your home screen and re-add it via the browser's "Add to Home Screen" option. This always loads the latest version.
Your data is safe
All your settings, saved snapshots, and assumptions are stored in localStorage on your device — they are completely separate from the app cache. Clearing the app cache or reinstalling the PWA does not delete your data. Only tapping ↺ Reset in the header, or clearing your browser's site data (not just the cache), will remove stored settings.
Current version
This app is running . The version number is also shown in the header subtitle on desktop. If you want to confirm whether you are running the latest version, compare this number against the latest release on the project's GitHub repository or ask your system administrator.
Inverter sizing
Tell us about your large appliances to get a recommended inverter size

Hot water system

Air conditioning

Cooking appliances

Pool, spa & outdoor

Other large appliances

Always-on baseline

Battery charging & free power window

When the battery charges during the free power window (11 am–2 pm), the inverter must simultaneously handle: solar DC conversion, battery charging current, household loads, and — if applicable — EV charging. The hybrid inverter's battery charger rating is the key constraint on how fast the battery can charge.

See how your inverter size feeds into the recommendation.
🌞 Optimal usage advisor
Maximise solar self-consumption by timing appliances around solar generation

⚙️ Simulation settings

🏠 When do you run these appliances?

Set the typical time window for each appliance. Only appliances configured on the Inverter page appear here. The advisor compares your schedule against the solar curve and flags the best shifts.

EV charging
—
Hot water
—
Pool pump
—
Air conditioning
—Comfort-driven
Dishwasher
—
Washing machine
—
Dryer
—

📅 24-hour energy profile

Solar generation Total load Grid import Battery SoC

💡 Optimisation recommendations

📈 Estimated annual savings from optimisation

Ready to validate a quote against your optimised setup?
Saved snapshots
Your saved recommendations, results, and battery comparisons

Transfer settings

Export all your current settings to a file and load them into another device or browser — or share a configuration with someone else. The export includes all inputs, assumptions, installer proposals, and your current electricity bill.

📤 Export settings

Downloads a .solarsettings file containing your complete configuration.

📥 Import settings

Load a previously exported .solarsettings file to restore all settings.

Power provider advice
Tailored tariff and plan recommendations based on your system and usage
Configure your system on the Setup page to generate recommendations.
Ready to validate a quote against your setup?