Solar system advise needed

You could probably run the 120 volt items listed on a 300 watt pure sine wave inverter.

The battery bank size would be determined by the total run time of the items using 100 watt = ten amps per hour of use.

For example, if the computer draws 80 watts and is used for 8 hours, it would use 640 watts and require 64 amp-hours. Since even deep cycle batteries need to be kept above 50% the battery requirement for that one item is 128 amp-hours.

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT. What ever type of controller is chosen, make sure it has adjustable set points and a temperature probe that is on the battery.

One rule of thumb is between 60 and 150 watts of panels per 100 amp-hours of storage. The smaller the battery bank the higher the wattage needed (per 100 amp-hours). Here is a link to the rather special spreadsheet which includes an energy audit, that N8GS has created to help size solar battery charging systems!

Solar Spread Sheet N8GS

For a nice explanation of solar, try this link:

Golden rules of solar

Depending on outside temps, the furnace can pull 40-60 amp hours a day (with snow everywhere). Where you are going to winter is an important variable in this equation. Will you ever have hookups, how often. Batteries can be short cycled (not charged to 100%) a few times, but it doesn't take long to damage them (10-15 cycles).
The TV and computer are going to be expensive loads (power demand wise).

You could get by on two batteries if the sun is good every day or you have a small generator to use if needed. Otherwise with a few cloudy days and no generator I recommend 4x GC2 (golf car batteries).

Again 200 watts solar will work great when conditions are good. 300 to 400 watts would serve better when the sun breaks out after a few bad solar days.

Solar controller keeps the battery charged. Inverter will supply 120vac from the battery. I have and recommend the Go Power 300 watt sine wave inverter for the usage posted. Very low idle current and has a provision for a remote power switch.

Price and compare 12v panels at the Isc rating (short circuit amps) not wattage. High voltage (24+v) panels are lower cost, physically larger, and require a higher cost MPPT controller. Make sure the panels will fit properly with 12 to 18" spacing away from shade items like air conditioner, open vents and antenna. Even small partial shading can cut power significantly.

> Forum Members Solar Installations With Pics

First I think you have to economize. Led bulbs etc. I find 7 amp charge works for me during the day. If I was dry camping 24/7/365 then much more. Depends on your style of camping. If I was a TV adict more is required. I sit by the fire outside and enjoy roughing it. we don't run into any problems. How much you need depends on your RV and life style.

A 500 watt inverter that plugs into a cigarette lighter will work, and only cost $40. You can install several cigarette lighter receptacles in the RV and use the small inverter anyplace you might need it. I would wire it up with #10 wire and a 20 amp fuse. While only good for about 250 watts, you probably will not use more than that anyway.

For solar panels, contact this place, and look for 12 volt 'nominal panels' that are 20.5 to 22 volts open circuit. And a PWM controller. They are fairly low cost, I bought a 10 amp PWM controller for about $20 last summer.

SolarElec.com

For mounts, I suggest 6" long of 2" angle aluminum from Home Depot. Drill 3 each 3/16" holes for #10 screws into the roof, and 5/16" hole for the 1/4-20 bolts into the solar panel framework.

I ran #10 romex direct burial wire through the refrigerator vent to my controller, then to the battery. (Home Depot).

I started with a pair of 45 watt panels (in 1994 it was a good cost for $750 to buy the kit, along with mounts, instructions, and wire.)

I installed a 75 watt panel ($375 at the time) in 97, and pair of 120 watt panels for $429 each in 1999. Now you can buy a 100 watt for about $100 or so.

I would recommend at least 200 watts. Your RV will consume 35 amp hours daily just running the CO and propane detectors, along with the refrigerator. Add the 30 amps that the furnace can use in 24 hours, and 10 - 15 amp hours for lights, 20 - 50 AH for computer, TV and Satellite dish, you get a total around 120 amp hours for my system, and I could make up that much power on a short 9 hour day in November.

If you like 200 watts, you really would like 400 watts, and probably would not need to run a generator. 600 watts, and you will not need to be conservative with the lights either!

I have a Olympic Catalytic Safety Heater, and it does not use any 12 volt power, totally silent, and you need to leave a roof vent open about 1/2" and window open a little too. Just like burning gas on your stove, you need to leave a window and roof vent open. The 6,000 Btu keeps my 30' Bounder toasty warm at 19F outside, with only a little furnace run time each night.

Good luck!

Fred.

Check out Arizona Wind and Sun web sit. also Handy Bob web site.

Lillyputz

Very, very valuable and helpful information. Thanks to all.
wademartin

I addition to the previous comments, you might consider flexible rather than hard case panels. They are easier to install.

too much rant, and some errors.

lillyputz wrote:
also Handy Bob web site.

Lillyputz

"Now you can buy a 100 watt for about $100 or so."

Most every site I go to has nothing anywhere near $1/watt. Where are you guys finding these?