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Airstream 1967 off grid plan

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  • #16
    Reed, do you have any pictures of the way you have the solar panels on the RV's? My Airstream is 24 feet, so in between your two. What is dirty power? Here on my farm I power two houses. The well pump and septic pumps are electric. The farm used 1117KWH for the month of March, which was cold. There is a gas furnace in the smaller house and both a boiler and electric baseboard heat in the bigger house. I feel this is not much power, but I do not understand 1420W at 10,400' yet.

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    • #17
      Originally posted by Sunny Eileen View Post
      The farm used 1117KWH for the month of March
      You need to learn the math because you are in for a shock.

      Watts is the unit of power. Example 100 watt light bulb or solar panel.
      Watt Hours is a unit of energy used over times. So if you used a 100 watt light bulb for 10 hours = 1000 watt hours or 1 Kwh.

      Watt Hours = Watts x Hours

      So your house used 1117 Kwh in a month means you used 1117 Kwh / 30 days = 37.2 Kwh each day. Get ready for an eye opener. I will assume you live in a decent location with decent Sun Hours and receive 4 Sun Hours in March. That would be an area like central coast of CA with lots of sun shine. A battery system at best is 67% efficient which means the panels have to generate a minimum of 37.2 Kwh / .66 = 56.36 Kwh.

      So some simple math can be applied to find the panel wattage required. Watts = Watt Hours / Hours. so 56.36 Kwh / 4 Sun Hours = 14.09 Kw. Translated it would take a panel array of 14,000 watts. Around $20,000 worth of panels and a few semi truck campers, but that is the inexpensive part and lightweight stuff. Next is batteries.

      To supply you with 37.2 Kwh per day with batteries is going to be a little 9000 pound, $30,000 battery you get to replace every few years.

      The math is real important and you need to learn it real fast so you understand what you are asking for.

      Here is a little math fun problem. You have a 100 watt light bulb you want to run 24 hours a day.

      That light bulb consumes 100 watts x 24 hours = 2400 watt hours. Think of it like hourly wages. 'Easy Peazy.

      You have a 4 sun hour day and you must generate at least 2400 x 1.5 = 3600 watt hours to use 2400 wh. with a 4 Sun hour day 3600 / 4 hours = 900 watt panel.

      For the 12 volt battery 2400 wh x 5 / 12 volts = 1000 AH a little $2400, 700 pound battery. All that to generate 25-cent of electricity.
      Last edited by Sunking; 05-22-2017, 08:27 PM.
      MSEE, PE

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      • #18
        The total output capability of reeds (6) 235w panels is 1410W , the nameplate wattage of solar panels (235w in this case) is under perfect conditions when tested by the manufacturer, well over 90% of the time with any solar panel(s) in any location, you will get something less from them, however it is not uncommon to achieve the rated wattage or slightly higher for brief periods of time during certain conditions, even with near nameplate output you are looking at around 6 to 9 kwh per day maximum, in a good sunny summer location (not Creston in winter), 9 x 30 = 270 kwh per month, you can see by comparison to the 1100kwh you used that is about 25%, and the 235w panels are roughly 3' x 5' each 35-40 lbs each.
        Last edited by LETitROLL; 05-22-2017, 10:22 PM.

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        • #19
          Your current consumption of 37.2kWh per day is allot of energy to generate with solar and store in a battery. Our off grid system gives us about 3kWh of energy each day in winter with around 4.5kWh/panelkW/day (sunshine hours). Of this around 1kWh runs the fridge, 1.5kWhs runs lights, toaster and a few kettles of hot water, computers, washing machine every few days etc. 0.5kWh gets lost.

          I would think it impractical to do any heating in winter in your part of the world using solar.

          Simon

          Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
          BMS - Homemade Battery logger github.com/simat/BatteryMonitor
          Latronics 4kW Inverter, homemade MPPT controller
          Off-Grid LFP(LiFePO4) system since April 2013

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          • #20
            I do not plan to stay here. Creston BC is most likely where I will go and for a few cold months in the winter, I plan to relocate to a warm country. I only gave my power consumption where I currently live as a reference. I have 2 houses and a farm and feel I do not use much power. I am thinking of a system more like Simon's.

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            • #21
              Sunny Eileen - We were "camped" at 10,400' elevation near Rocky Mountain National Park. Just to see how much we could harvest, we ran fridge (absorption and not efficient with electricity), hot water, and air conditioning (even though it was in low 70s) and got 8.5 kW-hrs that day as LETitROLL intimated.

              Had the 315 W panel blow off roof due to fatigued brackeets at Los Ventos (the winds) in Isthmus of Tehuantapec (south of Oaxaca) where seven semis were rolled by winds one day last year. Our son and family visited us on beach in Yucatan and I go several meters of 1.5" aluminum L-bracked and we used this to remount the panel. We left rigs with older son and are with daughter in Las Cruces, NM and do not have rig with us but will post photos later if you wish.

              There are probably problems in mounting rigid panels to the curved roof of your RV. We know little of flexible panels but they should work on Airstream. Both Simon and Karrak have a lot of knowledge and might have suggestions. Might suggest Airstream fora.

              Reed and Elaine

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              • #22
                Originally posted by Sunny Eileen View Post
                Ok, no wind turbine while driving. But I still want to try one when parked.
                If you can afford to erect a 40-50 foot tower each time you change locations might be doable. But most people don't want to do that - it's too hard, it takes too much space, it's too much of a lightning risk etc.

                Things that do NOT work:

                -Putting your turbine on a short (5') pole on top of your RV
                -Putting it atop a nearby tree
                -Getting a short stand (5-10') and just putting it somewhere nearby

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                • #23
                  Originally posted by jflorey2 View Post

                  If you can afford to erect a 40-50 foot tower each time you change locations might be doable. But most people don't want to do that - it's too hard, it takes too much space, it's too much of a lightning risk etc.

                  Things that do NOT work:

                  -Putting your turbine on a short (5') pole on top of your RV
                  -Putting it atop a nearby tree
                  -Getting a short stand (5-10') and just putting it somewhere nearby
                  Where I see those smaller wind turbine a lot are mounted on sail boats in most of the marinas here is Florida. On the open water the wind seems to be pretty constant.

                  Along with a couple of solar panels they seem to provide some amount of power for lighting or electronics and do not have to run an engine to charge the batteries.

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                  • #24
                    Originally posted by SunEagle View Post
                    Where I see those smaller wind turbine a lot are mounted on sail boats in most of the marinas here is Florida. On the open water the wind seems to be pretty constant.

                    Along with a couple of solar panels they seem to provide some amount of power for lighting or electronics and do not have to run an engine to charge the batteries.
                    Yes, and they are also quite popular as charge maintainers for batteries when the boat is moored. When moored you get a few watts, then when underway you can get 50-100 watts due to the induced wind.

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                    • #25
                      Originally posted by jflorey2 View Post
                      Yes, and they are also quite popular as charge maintainers for batteries when the boat is moored. When moored you get a few watts, then when underway you can get 50-100 watts due to the induced wind.
                      The benefit of wind power comes from the long distances of open water and pretty constant air flow.

                      You can't say the same for a land based wind turbine system unless it is on a very tall pole or on the edge of a very large lake.

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                      • #26
                        Older son is in alternative energy (26 years) and he does put in aeolian power stations in New Mexico but he talked us out of using one on our 5th wheel. As full time RV'ers we have seen a few places where wind power would have been useful such as coasts of Newfoundland and Labrador. The winds on the beach of Yucatan would have been sufficient but we are only there 4 to 6 weeks each year. However, a wind turbine would have just been extra weight and volume the other 40+ weeks of the year.

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                        • #27
                          Eileen - "dirty" power is electrical power that varies greatly in voltage or amperage and which can damage the electronics in your system. Some of the power in RV parks can vary from 60 to 150 V. We burned out air conditioners in Baja and Yucatan. Older son and family came down to visit us on beach six years ago and brought down battery chargers so that the line power goes directly to battery bank and power comes from thre via Mean-well converter (48 V to 12 V on 5th wheel) and PSWIs. We ran into a couple that plugged in near Oaxaca and the panel was 220 V. They burned out all electronics in their RV.
                          Reed and Elaine

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                          • #28
                            Oh, that is not good, that dirty power. How does one know when it is that way?

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                            • #29
                              Originally posted by Sunny Eileen View Post
                              Oh, that is not good, that dirty power. How does one know when it is that way?
                              The only way to really know would be to measure it with a power quality meter.

                              There are devices that you can plug your RV into that will protect it if the power falls outside the good range.

                              I have one that is rated 50amp made by Progressive industries model EMS-PT50C

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                              • #30
                                Originally posted by jflorey2 View Post
                                Yes, and they are also quite popular as charge maintainers for batteries when the boat is moored. When moored you get a few watts, then when underway you can get 50-100 watts due to the induced wind.
                                Yes they work with boats. Not many trees or obstructions to deal with.

                                MSEE, PE

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