Detailed DC system design
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Location: Pampachiri, Apurimac, Peru
GPS coordinates: 14°11'37.65"S 73°32'31.73"W
Altitude: 3378m
Description: A two story adobe home in the Peruvian Andes with only DC power needs.
Photo of the home.
Location of the home.
DC load evaluation
| # | Load | Quantity | Watts | Total watts | Duty cycle | Hours per day | Days per week | Average daily DC watt-hours |
|---|---|---|---|---|---|---|---|---|
| 1 | Cree 5 W LED | 6 | 5 W | 30 W | 1 | 3 hours | 7 days | 90 Wh |
| 2 | Retekess radio | 6 W | 1 | 6 W | 1 | 5 hours | 7 days | 30 Wh |
| 3 | Samsung cell phone | 2 | 10 W | 20 W | 1 | 1 hour | 7 days | 20 Wh |
| Total average daily DC watt-hours | 140 Wh | |||||||
- Load: The make and model or type of load.
- Quantity: The number of of that particular load.
- Watts: The power rating in watts of the load.
- Total watts = Quantity × Watts
- Duty cycle = Rated or estimated duty cycle for the load. If the load has no duty cycle a value of 1 should be used. A load with a duty cycle of 20% would be inputted as .2
- Hours per day: The maximum number of hours the load(s) will be operated per day. If the load has a duty cycle 24 hours should be used.
- Days per week: The maximum number of days the load(s) will be operated per week.
- Average daily DC watt-hours = Total watts × Duty cycle × Hours per day × Days per week ÷ 7 days
- Total average daily DC watt-hours = sum of Average daily DC watt-hours for all loads
Average daily watt-hours required
| Average daily watt-hours required | = Total average daily DC watt-hours + Total average daily AC watt-hours |
|---|---|
| Average daily watt-hours required | = 140 Wh |
Load and solar resource comparison
21.66623678 25.89395808 23.35798899 24.00274317 19.59777892 20.99475131 19.96672213 18.26404592 33.1047529 19.55125221 19.72664506 23.73149508
| Month | Average daily insolation | Average daily Watt-hours required | Ratio |
|---|---|---|---|
| January | 193.85 kWh/m² / 30 = 6.46 kWh/m² | 140 Wh | 21.67 |
| February | 162.2 kWh/m² / 30 = 5.41 kWh/m² | 140 Wh | 25.90 |
| March | (179.81 kWh/m² / 30 = 6.00 kWh/m² | 140 Wh | 23.36 |
| April | 174.98 kWh/m² / 30 = 5.83 kWh/m² | 140 Wh | 24.00 |
| May | 214.31 kWh/m² / 30 = 7.14 kWh/m² | 140 Wh | 19.60 |
| June | 200.05 kWh/m² / 30 = 6.67 kWh/m² | 140 Wh | 20.10 |
| July | 210.35 kWh/m² / 30 = 7.01 kWh/m² | 140 Wh | 19.97 |
| August | 229.96 kWh/m² / 30 = 7.67 kWh/m² | 140 Wh | 18.26 |
| September | 126.87 kWh/m² / 30 = 4.23 kWh/m² | 140 Wh | 33.10 |
| October | 214.82 kWh/m² / 30 = 7.16 kWh/m² | 140 Wh | 19.55 |
| November | 212.91 kWh/m² / 30 = 7.10 kWh/m² | 140 Wh | 19.73 |
| December | 176.98 kWh/m² / 30 = 5.90 kWh/m² | 140 Wh | 23.73 |
- Month: The month of the year.
- Average daily insolation: Solar resource data obtained for the location from Weather and solar resource data sources.
- Average daily Watt-hours required from load evaluation.
- Ratio = Average daily Watt-hours required ÷ Average daily insolation
