Advanced Examples
Examples
These are examples of how the SolarSizer software can help you design solar systems. Far more detailed examples, that show wiring, equipment sizing, documentation, etc., are in the Solar Design book.
Example 1, Grid-Connected Residence
This is an example of a grid-connected residence in Albuquerque, New Mexico. The array will be mounted on a roof surface that is oriented at 160° (20 degrees east of south) and tilted to 33.7° (8 in 12 pitch). The energy use is known to be 8,000 KWh per year. With some energy efficiency improvements, the energy use is expected to be 7,300 KWh per year. 50% of the utility bill will be offset by the solar system.
The SolarSizer program is used to calculate the solar array size. Losses are estimated to be 3% for wiring, 10% for soiling, and 10% for aging. The inverter efficiency is estimated to be 92%. The roof gets full sun.
The SolarSizer program calculates a required array size of 2.208 KW.
Read more about this exampleExample 2, Grid-Connected Residence 2
This example is the same as Example 1 except the array will be mounted on the ground, which will allow the optimization of the tilt and orientation angles. The energy is expected to be 7,300 KWh per year after energy efficiency improvements. 50% of the utility bill will be offset by the solar system.
The SolarSizer program is used to calculate the solar array size. Losses are the same as Example 1, estimated to be 3% for wiring, 10% for soiling, and 10% for aging. The inverter efficiency is estimated to be 92%. The array gets full sun.
The SolarSizer program calculates a required array size of 2.144 KW at an optimum tilt of 42°.
Read more about this example
Example 3, Grid-Connected Residence 3
This example is the same as Example 1 and 2 except the array will be mounted on a two-axis tracker. The energy is expected to be 7,300 KWh per year after energy efficiency improvements. 50% of the utility bill will be offset by the solar system.
The SolarSizer program is used to calculate the solar array size. Losses are the same as Example 1, estimated to be 3% for wiring, 10% for soiling, and 10% for aging. The inverter efficiency is estimated to be 92%. The array gets full sun.
The SolarSizer program calculates a required array size of 1.738 KW.
Read more about this example
Example 4, Water System
This is an example of a water system. The site is Albuquerque, New Mexico. The array will be mounted on the ground, oriented to 180° and tilted to 42°. The water use is 200 gallons per day. The storage tank supplies 15 days of water and the pump is sized to fill the tank in 5 days. There is a fire reserve of 6,000 gallons. Water use is assumed to be constant throughout the year. The pump is directly connected to the solar array without batteries. The total dynamic head is 120 feet.
The SolarSizer program is used to calculate the tank size, pump size, and solar array size. Losses are estimated to be 10% for wiring, 10% for soiling, and 10% for aging. The pump efficiency is estimated to be 42%. The array gets full sun. The pump control uses 10 Watts.
The SolarSizer program calculates the required tank size as 9,000 gallons, the required pump size as 0.195 horsepower and 2.52 gpm, and the required array size as 199 Watts. A prudent system designer would add some margin to these numbers.
Read more about this example
Example 5, Battery System
This is an example of a battery system. It is for a cabin in the mountains near Kalispell, Montana. The cabin is use in the summer from June through August. The cabin will have a 12-Volt system to run lights, a small refrigerator, a music center, and some other 12-Volt appliances. The refrigerator is an energy efficient model and the lights are LED type. The energy use is 1,500 Wh per day and the maximum draw on the battery is 480 Watts or 40 Amps. The array will be ground mounted, oriented south and tilted to the most optimum angle for the summer use. Two parallel sets of two each series connected 6-Volt batteries are planned (four 6-Volt batteries total).
The SolarSizer program is used to calculate the battery and array size. Losses are assumed to be 10% each for the wiring, soiling and aging. The efficiency of the charge controller is assumed to be 96%. The batteries return 80% and 50% discharge is planned. The battery bank is sized to run the cabin for 3 days and the array is sized to charge the battery bank in 3 days. There is a standby generator in case there is a string of cloudy days and to run the washing machine and power tools.
The SolarSizer program calculates the required battery size to be 375 Amp-hours each for a total of 9,000 Wh. It also calculates the array size as 802 Watts when tilted at the optimum angle of 27°. The latitude of Kalispell is 48°. If the cabin was used year round, the array size and optimum tilt would be much different. With the 12 volt appliances off, the system produces enough energy to keep the batteries charged during the winter. The owner tilts the array up to 60° to keep the snow off during the winter.