Load Estimate Worksheet

Loads / Qty / x / Volts / x / Amps / = / Watts
AC DC / x / hrs/
day / x / Use/
week / / / 7 / = / Watt hours
AC DC
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Total AC Connected Watts / Average AC Daily Load
Total DC Connected Watts / Average DC Daily Load
BLuePanel Energy Systems / Total Average Load (add above)
Adjusted watt hour (divide by 0.8)

Print this work sheet and use it to calculate your daily or weekly energy requirements. One deep-cycle 6-volt golf-cart battery or 12-volt RV battery will store approximately 1 kWh of energy. As a rough estimate, this means you will need about 200 watts of solar array to recharge one battery in one day, assuming five hours of direct sunlight, this is 1 kwh.

This estimate does not have to be exact, the closer you get, the better you will be able to design your system. It makes it much easier if you have have these numbers.

Battery Bank Sizing:

A good rule of thumb is to size the system to provide power for 3 to 5 days (days of autonomy). Using 3 days is a good number, while selecting 5 days may result in a battery bank that is quite expensive. For the example we will use only one day.

example: calculated using a 1500w heater for 1 hr/day this will show what it takes to run high a consumption load even for a short time.

We first need to convert watt-hours to amp-hours since that’s how batteries are rated:

2140 adjusted watt-hours per day/12 (our system voltage) = 178 amp-hours required per day. You will need to increase this to keep from deeply cycling your batteries and extend their life. A good factor is 2x, this will cycle your batteries to roughly 50% giving you good battery life.

178 amp-hours x 2 = 356 ahr @12 volts, you now need a way of putting back the 178 ahrs to be able to use them again the next day.