Battery kWh
Battery capacity is normally expressed in kilowatt-hours (kWh). A larger battery can store more energy.
SOLAR8 KNOWLEDGE CENTRE
Solar SystemSizing Made Simple.
How much solar do you need? Learn how inverter power, battery capacity, solar panels and your electrical loads work together to create the right system for your property.
THE BASICS
Solar sizing starts with how you use electricity.
The right solar system is not simply the biggest system you can afford. It should be designed around your actual electricity demand, the appliances you want to run, your backup requirements and how much solar energy your property can produce.
There are three main questions to answer when sizing a solar system:
01How much power do my appliances need at the same time?
02How much energy do I want to store in my batteries?
03How much solar energy do I need to generate during the day?
THE THREE PARTS OF SYSTEM SIZING
InverterHow much power?
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BatteryHow long?
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SolarHow much generation?
01 — INVERTER SIZING
How big should your inverter be?
Your inverter is primarily concerned with power. Its rating determines how much electrical load the system can supply at a given moment.
kW
Power capacity
An inverter rated at 5 kW can supply approximately 5 kW of electrical power under the appropriate operating conditions.
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Think about simultaneous loads
If several high-power appliances operate at the same time, their combined demand may determine the inverter size required.
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Allow for future needs
A system should also consider appliances or electrical loads that you may add in the future.
SIMPLE EXAMPLE
Why simultaneous loads matter
Imagine a property running a kettle, microwave, refrigerator, lighting and other appliances at the same time. The inverter needs to handle the combined electrical demand rather than simply looking at the monthly electricity bill.
Inverter sizing = power demand02 — BATTERY SIZING
How many batteries do you need?
Battery sizing is mainly about energy capacity and how long you want selected appliances to operate without grid power.
How long?
The amount of usable battery energy and the power being consumed determine how long the battery can support your selected loads.
What must stay on?
Backup systems are often designed around essential loads such as refrigeration, lighting, internet, security and selected household circuits.
SIMPLE WAY TO THINK ABOUT IT
Battery capacity → backup energy
More battery capacity generally means more stored energy available for later use. Actual backup time depends on the loads being supplied and the usable battery capacity.
03 — SOLAR PANEL SIZING
How many solar panels do you need?
Solar panels determine how much energy your system can generate during the day.
Panel capacity
Each panel has a rated power output, normally expressed in watts. Multiple panels are combined to create the required solar array.
Sunlight matters
Actual production varies with sunlight, weather, temperature, orientation, shading and the installation itself.
Daily energy production
The solar array should be considered together with your electricity consumption and battery charging requirements.
Installation limitations
Roof space, panel orientation, shading and inverter specifications can all influence the final design.
LOAD SHEDDING & BACKUP
What do you actually want to keep running?
A backup system does not necessarily need to power every appliance in the property.
ESSENTIAL
Common backup loads
- Refrigerator
- Lighting
- Wi-Fi / Internet
- Security systems
- Television and electronics
- Selected plugs
HIGH-DEMAND
Loads requiring more planning
- Electric geysers
- Electric stoves
- Large air conditioners
- Pool pumps
- Electric heaters
- Other high-power equipment
Important:
Whether an appliance can be included in a backup circuit depends on its electrical demand, the inverter capacity, installation configuration and the overall system design.
CHOOSING A SYSTEM
Different properties need different solutions
There is no single solar system that is right for every property.
Keep the basics running
Suitable when the main objective is maintaining essential household services during power outages.
- Essential appliances
- Smaller battery requirement
- Focused backup circuits
Savings + backup
A hybrid system combines solar generation, battery storage and grid electricity to provide greater flexibility.
- Daytime solar savings
- Battery backup
- Flexible energy management
Larger energy requirements
Properties with larger electrical loads may require additional inverter capacity, battery storage and solar generation.
- Higher loads
- Larger solar array
- Greater storage requirements
QUICK REFERENCE
The numbers you need to understand
kW
Power. Used to describe the power capacity of an inverter and the demand of electrical loads.
kWh
Energy. Commonly used to describe battery capacity and electricity consumption.
Load
The electrical demand created by appliances and equipment.
Usable Capacity
The portion of a battery's capacity that can practically be used by the system.
Backup Load
An electrical circuit or appliance selected to remain powered when the grid is unavailable.
Solar Array
A group of solar panels connected together to generate electricity.
NEED HELP WITH SIZING?
Let Solar8 work out what your property needs.
Your electricity usage, appliances, backup requirements and property all influence the right solar system. Start with an assessment before choosing equipment.