Solar Example Only
Appliances Watt Hours/ Day Hours/ Day Watts/ Day
Refrigerator (with ice maker) 92 x 24 = 2208
Bathroom Lights = 5 x 20w 100 x 3 = 300
Bedroom Lights = 4 x 20w 80 x 4 = 320
Computer System 200 x 4 = 800
Ceiling Fans = 10 x 70w 700 x 12 = 8400
Kitchen Lighting = 2 x 20w 40 x 6 = 240
Living Room Lights = 5 x 20w 100 x 6 = 600
Misc Kitchen Appliances 1200 x 0.25 = 300
Radio/Stereo 30 x 1 = 30
Refrigerator Ice Maker 50 x 1 = 50
TV = 2 x 150w 300 x 4 = 1200
Water Pressure Pump 100 x 1 = 100
Total watt hours per day = 14,578
Multiply by 1.20 for Inverter Loss = 17,494
Calculations For Number of Solar Panels Needed
Total Watts Used per Day 17,494
Number of Sunlight Hours for Charging 5
# of Watts a 165w Solar Panel Will Produce in 5 Hours 825
Divide 825w into 14,844w This = # of Panels Needed 21.20
Round Up to Even Number of Solar Panels 22
Cost Estimate for 165w Solar Panel $595.00
Number of Solar Panels x $595.00 $13,090
Calculations For Battery Sizing
Watts / Volts = Total Amps Used per Day (14,578w / 12v) 1458
184 Amp Battery 184
Only Discharge Battery to Half Life 92
Total Amps / Battery Amps Available (1237a / 92a) 15.85
(Round up to Even Number) Number of Batteries Needed 16
Cost Estimate of 184 Amp Batteries $179.00
Total Cost of Batteries $2864.00
Pricing Calculations
22 Solar Panels 165w $13,090.00
14 - 184 Amp Batteries $2864.00
4048 Power Panel Inverter System $4000.00
Cables and Mounts $1000.00
California Tax 7.75% $1624.00
Total Cost Estimate of Solar System $21,578.00
a free-standing solar system is not solar powered but battery powered.
Power is transfered from 12 volt batteries to an inverter that transforms it into house current (120v).
As the power is taken from the batteries there must be a system in place to recharge the depleted batteries.
This is where the solar panels come in. There has to be enough energy provided to produce enough power to replace the power in the batteries the inverter took for the house current.
How to calculate number of solar panels needed:
1. How many watts of power you will use each day? This is done by listing each appliance, the watts it uses per hour, and the number of hours it will be on. Ours is 17,494 for the 5 casitas.
2. When you find this number, you now know how many watts the solar panels have to supply the batteries during sunlight hours. Baja is rated as an average of 5 hours solar power available each day. This could be higher during certain times of year.
3. Now you decide what size solar panel you want to purchase. We will need several panels so we choose a larger size. (165 watts).
4. In 5 hours these 165 watt solar panels will produce 825 watts.
5. To get the total number of solar panels need for Playa Frambes you divide Total Watts (17,494w) by the total amount of watts the solar panels will produce during daylight hours (825w). Playa Frambes needs 22 (165w) solar panels.
How to calculate number of batteries needed:
1. Batteries are rated in Amp/Hours. We choose 12 volt 184 Amp/Hour deep cell batteries available for $179.00 each because they are available in Baja later if we have a battery failure.
2. Since we know how many watts Playa Frambes will use per day, (17,494w) it is a simple conversion to convert watts to amps. (watts divided by Volts = Amps). Total Amps need per day will be 1458.
3. Batteries should only be discharged to half-power. This meand our 184 amp batteries are actually only 92 amp usable.
4. Divide total necessary amps (1458) by useable battery amps (92) to get number of batteries needed for one days storage. This number is 15.85 but there is no .85 battery so you ned to round up. (16 batteries needed
