Estimate your daily power needs and design your solar & battery system with Rainbow Power Company's free AI-powered calculator.
👋 Welcome! I'm Bowie, your energy calculation expert. Answer a few simple questions about your property and appliances, and I'll calculate your exact power requirements. Let's discover how much energy you'll need!
📧 Get Your Results! Complete the conversation with Bowie first. Once your energy calculation is ready, enter your details below to receive your personalized power requirements report via email.
Sizing an off-grid solar system correctly requires knowing your total daily energy consumption in kilowatt-hours (kWh). Too small and you'll run out of power; too large and you'll waste money. Follow these five steps using our free AI calculator:
Want to understand the maths behind the calculation? Read our full guide: How to Size an Off-Grid Solar System — Complete Australian Guide
Use this table to cross-check the values Bowie estimates, or to manually calculate your daily kWh: Watts × Hours per day ÷ 1000 = kWh per day
| Appliance | Typical Watts | Avg. Hours/Day | kWh/Day |
|---|---|---|---|
| Refrigerator (medium, frost-free) | 150 W | 8 h | 1.2 kWh |
| Split-system air conditioner (2.5 kW) | 850 W | 6 h | 5.1 kWh |
| LED lights (whole house, 10 bulbs) | 100 W | 5 h | 0.5 kWh |
| Electric hot water system (heat pump) | 500 W | 3 h | 1.5 kWh |
| Washing machine | 500 W | 1 h | 0.5 kWh |
| Chest freezer | 80 W | 8 h | 0.6 kWh |
| Television (55" LED) | 80 W | 4 h | 0.3 kWh |
| Laptop computer | 45 W | 6 h | 0.3 kWh |
| Water pump (pressure pump) | 750 W | 1 h | 0.75 kWh |
| Pool pump (0.75 kW) | 750 W | 6 h | 4.5 kWh |
| EV charger (Level 2, 7.4 kW) | 7400 W | 2 h | 14.8 kWh |
| Microwave oven | 1200 W | 0.3 h | 0.4 kWh |
Figures are typical averages. Actual consumption varies by model, usage pattern and climate. The AI calculator adjusts estimates based on your specific answers.
A solar load calculator helps you estimate your daily electricity needs before designing an off-grid or hybrid solar system. It identifies your major energy consumers — air conditioning, water heating, pool pumps, fridges, lighting — and calculates how many kilowatt-hours (kWh) you consume every day. This figure is the foundation of every solar system design.
This tool, developed by Rainbow Power Company, uses an AI assistant called Bowie to guide you through a friendly chat. Bowie asks about your lifestyle, the appliances you use, and your daily habits. It then extracts each appliance’s wattage and hours of use to build a complete load list and calculate your total daily energy consumption in kWh. Once complete, you receive a personalised energy report by email — free of charge.
Divide your daily kWh consumption by the average peak sun hours for your region (4–5 hours across most of Australia). Add 20–25% to account for system losses, shading and inverter efficiency. For example:
Use this calculator to find your specific daily kWh figure, then Rainbow Power Company’s engineers will recommend the right panel capacity.
Battery sizing depends on your daily kWh usage, desired days of autonomy (how many cloudy days you can survive without sun), and the battery chemistry:
Example: 10 kWh/day × 2 days ÷ 0.8 = 25 kWh of lithium battery capacity required.
Off-grid solar is a completely standalone system — no grid connection. All power comes from solar panels and batteries. This is common for remote rural properties, farms and areas where grid connection is prohibitively expensive.
Hybrid solar includes solar panels and battery storage but remains grid-connected. You use your own solar first, store excess in batteries, and only draw from the grid when batteries are depleted. Hybrid systems offer grid backup while significantly reducing electricity bills.
Accurate load estimation is the single most important step in designing a reliable solar system. Undersizing means your system runs out of power on cloudy days or during peak usage. Oversizing means you spend thousands more than necessary on panels and batteries. A correctly sized system provides reliable power year-round at the lowest possible cost. It’s essential for anyone planning to go off-grid or reduce reliance on the utility grid in Australia.
Yes — completely free. The Off-Grid Solar Load Calculator is provided at no cost by Rainbow Power Company. After completing the chat with Bowie, you receive a detailed energy report by email with no obligation to purchase anything.
Learn more about off-grid systems at Rainbow Power Company — Australia’s off-grid solar specialists since 1987.