Solar Power for your RV?

author image

May 26, 2008

What’s the Fuss About Solar ?!

Howdy !

Looking at the questions asked about the solar power articles that I’ve done for rv magazines and on this BLOG it seems to me that solar power is somewhat misunderstood because we don’t have the information to provide real answers.

Here is the most common question:

Q.     What does it cost to put solar on a RV ??

A.     How much have ya got ?!

This is the most common question and the hardest to answer because there is no real way to answer it. It’s kinda like the chicken or the egg type question. The first thing you must know before we can even begin to get to the bottom of this one is – how much power do you need ?  We start by completing the power sizing chart to determine how much power we use.  To make this work we really do need to add-up ALL the devices we have in the RV, both 12-Volt DC and 120-Volt AC.  Let’s assume that we are designing a solar driven power system of solar panels, an inverter for 120 Volts AC, a battery bank and the needed controllers, cables and so on to make it all work.

Enter the Wattage marked on the ALL electrical items first then mutilply by the number of hours in a 4-hour “day” you use that device.  For example, if you use the water pump for a total of 1/2-hour a day then your total might look like 40-watts X 30 Min – 20-Watts of power used for the pump.  Modify the chart to fit the devices you use, like the satellite TV and DVR.  Don’t forget the little things like the electrict heater rod in the water heater, the carbon monixicide alarm and so on.

The resulting amp-hours total will amaze you !  The real shocker will be when you have multiplied that AC devices wattage by 10 to reflect the power loss from using an inverter system. OK, here is the chart –

Power sizing chart

DC Devices                                                             12 Volts Watts           X    Hours/Day =    Daily Watt Hours

AM/FM radio 12 Watts                                               ___________                                             _____________

CB radio 15 Watts                                                      ___________                                              _____________

Cassette/CD player 30 Watts                                    ___________                                               _____________

TV black/white 18 Watts                                          ___________                                               _____________

TV 9″ Color 40 Watts                                                ___________                                               _____________

TV 14″ Color 84 Watts                                              ___________                                               _____________

Incandescent light #1141 18 Watts                          ___________                                               _____________

Fluorescent – 1 tube 13 Watts                                  ___________                                               _____________

Fluorescent – 2 tube 26 Watts                                  ___________                                               _____________

Water pump 8 – 12 Gal/day 24 Watts                       ___________                                               _____________

Water pump 16 -24 Gal/day 48 Watts                      ___________                                                _____________

Forced air furnace 48-96 Watts                                ___________                                                _____________

Fantastic fan 120 Watts                                            ___________                                                _____________

Bathroom fan 18 Watts                                             ___________                                                _____________

Range hood fan 144 Watts                                        ___________                                                _____________

The AC appliances listed below require the use of an inverter. The AC Watts have been multiplied by a factor of 10 to show

the DC watts usage from the battery.

AC Devices 120 Volts                                              Watts              X      Hours/Day =                    Daily Watt Hours

Microwave oven 1650 Watts                                ____________                                                          _____________

Blender 198 Watts                                                ____________                                                          _____________

Vacuum cleaner 80 Watts                                    ____________                                                          _____________

Computer 55 Watts                                             ____________                                                          _____________

14″ Color monitor 100 Watts                               ____________                                                         _____________

Laser printer 1200 Watts                                     ____________                                                          _____________

Ink jet printer 35 Watts                                       ____________                                                          _____________

Electric clock 4 Watts                                          ____________                                                          _____________

Hair dryer 1500 Watts                                         ____________                                                           _____________

VCR 30 Watts                                                      ____________                                                            _____________

Sub total of daily watt/hours                                ___________

Multiply subtotal by .10 for battery inefficiencies ___________

Multiply subtotal by .4 if you leave panels flat     ___________

Multiply subtotal by .4 and subtract if you plan to

track the sun with your panels                              ___________

Adjusted daily watt/hours – – – – – – – – – – –    ___________

Divide by the average peak sun hours per day for

your area. – – – – – – – – – – – – – – – – – – –      __________

Add up the total watts used per day – – – – –       ___________

Total array watts needed – – – – – – – – – – – –    ___________

Ok, I’m going to leave you to figure our YOUR power needs for the normal operation of YOUR RV.  Do the homework and we will continue the system design next week when we have some real numbers to work with.

Later – – –

The Old Ranger

Leave a Reply


  1. Pingback: Where Do Extended Term Boondockers Get Their Power?








  3. Joe

    Old Ranger
    I’m new to this site, but I have been wondering how much solar cells/panel I need just to keep my 200Amp 12V wet cell battery fully charged.
    This is due to the fact that when fully charged, my inverter runs for at least 12 hour (depending on my consumption).
    I enjoy my battery output as it is. My constraint only is how to get it charged. I want to use solar to charge it. Pls help me.

  4. Mike Seffen

    Howdy !

    I did several articles on batteries, battery placement, types and cabling, all here on the BLOG. Take a look at them and see what you think.

    Later – –


  5. b wilson

    another comment about your 6v/12v battery choice, is what is the space that is available? and is it approprite for the type of battery you will use. ie. wet cell, or the newer (and more expensive !) AGM type. battery maint , even with just your exsisting system, is another topic ,also chargers, and the so-called chargers installed by many rv mfg’s. I have many other comments, and some actual ! suggestions. b.w.