Determining the proper size kit will depend on your overall load or daily watt hour (W/h) appliance consumption. A watt hour is a measure of power consumed over time; i.e. a 100 watt bulb left on for 10 hours is 1000 watt hours. 1000 watt hours = 1 kilowatt hour (kWh).

1) Find the rated wattage of each appliance that you will use and multiply that times the number of hours per day that you will use them (i.e. 90 watt TV x 2 hrs/day = 180 W/h). Then total all of the W/h ratings of each appliance to arrive at your total daily W/h load. If the wattage of an appliance is unknown but the amperage (amps) is, then multiply the voltage of the appliance times the amps to determine the wattage.

2) In determining the battery bank size, we'll divide your total daily W/h figure by the nominal battery bank voltage (usually 12 volts for most RV's, trailers and boats and 12, 24 or 48 volts for cottages & cabins). This figure gives us a daily amp hour (A/h) load. Multiply this A/h load times 1.2 to account for system inefficiencies and derating factors. You take this A/h figure and multiply it times the number of days you require stored power (1 -2 days is average). Then finally divide this A/h figure by the battery depth of discharge (usually .5 for 50% is standard to a maximum of 80% or .8). This will determine your overall battery A/h capacity required.

3) To determine the number of solar panels required, we take your daily A/h load and divide it by the peak sun hours of the day for the region your are located (4 - 5 peak sun hours per day is average). This figure is the total amperage required from your solar panel or array that will keep your battery bank charged and ready to go. We take the peak amperage rating of your solar panel and divide it by the total required amperage of the panel or array. This will determine the number of solar panels required in your array.

Remember, the greater the load, the larger the system size would be required. Of course, available roof space to mount the panel(s) is also a determining factor.

To help us determine what size system you would need, please click on the link below to download and print our Power Consumption Worksheet. Once you've completed the worksheet, you can either mail, email or fax it back to us with your contact information and we will advise you on the best system size for your RV, trailer, boat or cottage. Please Contact Us for more information.