Correct solar system sizing starts with load calculation. Instead of beginning with panels, start with energy consumption. Storage and panel capacity are determined by how much energy you actually use.
For a deeper explanation of load-first sizing methodology and storage planning, see this solar system sizing guide.
Step 1: Calculate daily energy use (Wh)
List all devices and multiply:
- Watts × Hours used per day = Watt-hours (Wh)
Sum all devices to determine total daily consumption.
For detailed load estimation logic, see:
Calculate generator power needs.
Step 2: Size battery storage
Battery capacity should cover:
- Daily Wh consumption
- Desired runtime without sunlight
- Safe depth of discharge
Example: If daily use is 2,000 Wh and you want one full day of backup, usable storage must exceed that number.
Review battery fundamentals:
Solar batteries and storage.
Step 3: Select inverter rating
The inverter must support:
- Total continuous watt load
- Highest surge load (motor startup)
See:
Inverter fundamentals.
Step 4: Determine solar panel array size
Panel sizing depends on:
- Daily Wh consumption
- Average peak sun hours
- System losses (temperature, wiring, conversion)
Panels must produce enough energy to recharge batteries within available sunlight hours.
Review panel behavior:
Solar panels explained.
Off-grid vs hybrid considerations
Fully off-grid systems require larger storage reserves and more conservative sizing. Hybrid or grid-assisted systems can operate with smaller battery capacity.
Off-grid planning reference:
Off-grid generators overview.