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These calculations will give you a good idea how much energy you use and how much solar energy is required to give a 100% self-sustaining electrical system during ideal weather. Consider your batteries as a bank account -- you cannot take out more than you put in plus the amount with which you started.
Conservation in use (withdrawals) and adequate production (deposits) is the key to a balanced electrical system.
Questions:
Considerations:
If you already have a generator, it can provide a backup. If you do not, we suggest you compare cost with equal value of solar panels. An RV furnace can use lots of propane and an enormous amount of battery electricity over a cold week end.
Leaving an outside light on all night can use as much power as what one panel can produce in half a day. An 8 hour day's drive can usually refill a battery bank from the alternator, unless you are running the refrigerator on 12 volt. Tilting panels during winter time increases output up to 30% for those spending more than two weeks in one spot. Each Rver has an individual "lifestyle" and habits on using electricity differently.
MAKING YOUR CALCULATIONS:
There are two ways to measure electrical consumption (Watts, AH). It is essential that you not mix Amp Hours with Watts. We find that converting to Amp Hours (AH) is simple, convenient and allows measuring panels, batteries and appliances on a common base. The APPLIANCE CONSUMPTION WORKSHEET (print it out) lists the approximate amp draw of typical appliances. Read the label on the appliance or measure with an ammeter.
Calculations:
| 1. | Energy used per day from worksheet (Total AH) | = __________ |
| 2. | Add 10% line loss & battery inefficiency: | = __________ |
| 3. | Grand Total AH: | = __________ |
| 4. | Assuming
a 4.5 amp (80 W) panel can produce 35AH in summer or 25 AH in winter under clear skies, determine how many panels you will need: |
= __________ |
If you have questions, write or call. Work out the calculations and have data
ready to tell us about unusual equipment you are using: 1-800-999-8520
COST FACTORS: How much will a solar system cost?
Top quality solar-panel cost is determined by the power produced. A 4.5 amp panel at sale price costs about $80/amp, add to that hookup accessories, regulatory, meters, brackets and wiring (approximately $100-$200) for a total of about $500 for a one panel system complete.