This tool recommends solar and battery system sizes based on device power consumption and location.
Voltaic Systems Options
equivalent sun: hours per day ( ), south facing, angled at °1
Solar Panel Performance in December
A power ratio of at least 1.5 is recommended.2| Panel | Power Ratio |
|---|---|
| 25W | |
| 50W | |
| 100W | |
| 200W |
Power Consumed = System Power * 24 hours
Battery Capacity
Batteries should be sized to run the device for at least 4 days with no sun in most situations.3
| Battery | Days Runtime |
|---|---|
| 18Ah | |
| 60Ah | |
| 96Ah |
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Footnotes:
- We recommend angling the panel to produce the most power in the worst month of the year, typically December in the northern hemisphere.
- This accounts for system losses as well as extended days of below average sunlight. Increasing panel size beyond a 1.5 power ratio decreases risk of an outage. Shade or other obstructions may require larger panels.
- Most places experience a few long stretches of below average sunlight or temperatures below freezing. In these situations, the battery may receive little or no charge
- 1 watt(s) x 24 hours = 24 watt-hours per day
- To make calculations easier, we equate the sun's path across the sky to time spent directly in front of the solar panel, or equivalent direct hours.
- Power Ratio = Power Generated / Power Consumed
- Number of days the system could run on only a battery