HOW SOLAR WORKS

It’s important for our customers to understand the basic functions of their new solar system to maintain and prolong the life of their system. Solar electric systems are simple to operate and have no moving parts. However, photovoltaic (photo = light and voltaic = voltage producing) or PV cells, employ sophisticated semiconductor devices, many of which are similar to those developed in the integrated circuit industry over the last 35 years. These are the “work-horse” behind your system, feeding your battery-bank, allowing you to utilize the sun’s energy for your comfort. Please read further to better understand how solar power works.

HOW MUCH SOLAR POWER DO YOU NEED?

  • Determine your solar charging goals and estimated power use
  • Continuous dry camping
    • Refill what you use each day, or at least each week
    • Verify light loads and no inverter, perhaps 75 – 150W
    • Small inverter w/light use (small TV, laptop, etc.), perhaps 150 – 300W
    • Large inverter may require large system, perhaps 300 – 500W+
    • Solar system should produce at least 3.5A per 100AH of battery
  • Non-continuous or long weekend dry camping
    • Refill only a portion of what you use each day
    • If you can last 3 days on 225AH (=70AH/day), one 100W module
      producing about 30AH per day can extend this to perhaps 5 – 6 days
  • Storage or maintenance only
    • 50 – 75W typically sufficient

SOME SYSTEM BASICS

  • Batteries don’t make electricity, they are simply a “storage tank”
  • Electrical energy is stored as chemical energy
  • Batteries store electricity in units called Amp-Hours (AH)
    Ah IS THE PRODUCT OF current (in amps) -times- TIME (in hours)
    10AH of consumption could be:

     

    • 5A for 2hr, 0.1A for 100hrs, or 100A for 1/10hr
    • Loads Remove AH from the battery
    • Charging sources Replace AH back into battery
  • Load AH consumption examples;
    • Typical coach standby – 0.5A x 24hrs = 12AH
    • 2 overhead lights for 4 hours 2.5A x 4hrs = 10AH
    • 2 hour movie w/satellite – 8A x 2hrs = 16AH
    • Microwave TV dinner via inverter – 130A x 0.1hrs (6 min) = 13AH
    • Inverter left on while mostly doing nothing – 1.5A x 24hrs = 36AH

PD MODULES

  • PV Modules are energy converters, turning light into electricity
  • In full sun 1m of OV modules will produce = 130 – 160W
  • Typical 12V PV module
  • Constructed with 36 cells in series
  • Typical V = 17V, V = 22V
  • 60 Cell “Grid Tie” modules
  • Typical V = 25V, V = 30V
  • Cost less in $/Watt compared to 36 cell module
  • May require more expensive charge control solution
  • Tipica full sun amp-hours delivered daily
  • Estimate daily AH by; 5hrs x (PMAX17v)
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