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Dual purpose "portable" solar setup for home and RV

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  • #16
    By the way, another relevant tidbit, we generally camp in warm, sunny parts of the country. That is not to say every day is sunny of course but we live in California and we camp mostly in the central valley of California where there is always sun except in the dead of winter (and we don't camp much in the winter anyway). So other than a couple of cloudy days on occasion, I would expect our panels to nearly always be collecting sun for the majority of days we are camping due to our location and the time of year we would be using it.

    If we decide to got to the Pacific NW, or another "modest sunlight" area of the country we would simply adjust our usage (and probably wouldn't need the A/C) to accommodate for the lower solar power we were able to generate.

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    • #17
      Originally posted by Tap2112 View Post
      By the way, another relevant tidbit, we generally camp in warm, sunny parts of the country. That is not to say every day is sunny of course but we live in California and we camp mostly in the central valley of California where there is always sun except in the dead of winter (and we don't camp much in the winter anyway). So other than a couple of cloudy days on occasion, I would expect our panels to nearly always be collecting sun for the majority of days we are camping due to our location and the time of year we would be using it.

      If we decide to got to the Pacific NW, or another "modest sunlight" area of the country we would simply adjust our usage (and probably wouldn't need the A/C) to accommodate for the lower solar power we were able to generate.
      I guess where someone camps is a desire for each person. I would rather find a site that has trees to get some shade, especially in the summer. But if you enjoy a lot of sun and no trees then you should have not problem getting enough for your solar panel system.

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      • #18
        Originally posted by Tap2112 View Post
        If we decide to got to the Pacific NW, or another "modest sunlight" area of the country we would simply adjust our usage (and probably wouldn't need the A/C) to accommodate for the lower solar power we were able to generate.
        Forget Air Conditioning period on Solar. Not going to happen no matter how much sun you have or do not have. Only way to have Air Conditioning is at an RV park with electrical hookup.
        MSEE, PE

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        • #19
          Originally posted by Sunking View Post
          Forget Air Conditioning period on Solar. Not going to happen no matter how much sun you have or do not have. Only way to have Air Conditioning is at an RV park with electrical hookup.
          Sunking, I have read many, many posts of yours on this website before ever posting my question here and I respect your knowledge and assistance. However, the "A/C" you are quoting from my post above isn't roof mount AC it is a small portable plug in unit as described in a previous post that you may have missed (or maybe not). It draws less watts than a microwave. I have a hard time believing I can't use that with the right solar/inverter setup.

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          • #20
            Originally posted by Tap2112 View Post
            I have a hard time believing I can't use that with the right solar/inverter setup.
            Sure it can be done if money and weight is no object. Once you learn exactly how much panel wattage and battery it requires you will become a believer. Here is another answer I gave to some guy who wants to run a very small 5000 BTU Window Shaker 6 hours per day.

            Panel Wattage = 1600 Watts. $3200
            65 Amp MPT Charge Controller. $500
            24 Volt 625 AH battery that weighs 900 pounds and cost $2200 every few years.
            24 Volt 2000 Watt TSW Inverter. $650
            Misc Materials $400
            Total Cost Est = $7000

            Here is the post. Reply 8. I say goferit. You will learn a lot.
            MSEE, PE

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            • #21
              Originally posted by Tap2112 View Post

              Sunking, I have read many, many posts of yours on this website before ever posting my question here and I respect your knowledge and assistance. However, the "A/C" you are quoting from my post above isn't roof mount AC it is a small portable plug in unit as described in a previous post that you may have missed (or maybe not). It draws less watts than a microwave. I have a hard time believing I can't use that with the right solar/inverter setup.
              You are not going to cool a camper with a 5k btu AC unit. much less power that unit from Solar. Most campers have 12k and 18k BTU air conditions due to the lack of insulation. a 5k BTU unit is no where enough, Might not even be enough to remove the humidity created by 2 bodies, much less the heat uptake of direct sun exposure. The weight of the batteries needed would load down your camper and cost more fuel to move said camper around. Still need AC, get a generator.

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              • #22
                Originally posted by Logan5 View Post

                You are not going to cool a camper with a 5k btu AC unit. much less power that unit from Solar. Most campers have 12k and 18k BTU air conditions due to the lack of insulation. a 5k BTU unit is no where enough, Might not even be enough to remove the humidity created by 2 bodies, much less the heat uptake of direct sun exposure. The weight of the batteries needed would load down your camper and cost more fuel to move said camper around. Still need AC, get a generator.
                I never suggested I was going to use a 5K btu unit. That was Sunking's response in another thread that he was posting here for reference. I have a 10K unit that uses about 950 watts and it quickly cools my 180 sq ft home office when I don't want to run my 5 ton central air unit if nobody else is home. It would easily cool the living space in my 5th wheel during the day if I were to close the bedroom and bathroom doors and could be moved to the bedroom in the evening if necessary.

                Whether it can be run strictly from solar is another story, but the cooling capacity of this unit is plenty for my RV needs based on the history of my usage at home.

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                • #23
                  Originally posted by Tap2112 View Post

                  I never suggested I was going to use a 5K btu unit. That was Sunking's response in another thread that he was posting here for reference. I have a 10K unit that uses about 950 watts
                  That would be a very low efficiency window shaker with an EER 10,000 BTU's / 950 watts = 10.5. As low of efficiency as Uncle Sam will allow made. Double the cost and equipment of a 5K unit. A 5th wheel trailer is not insulated like a home office setting out in the broiling Sun.

                  It would take a minimum 1500 watt panel to run off solar for a hour or two around noon. You would have to have at least a 12 volt 1000 AH battery or 24 volts @ 500 AH. Either way is a 700 pound $2000 battery. for just a few hours of cooling. Good luck with that.

                  MSEE, PE

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                  • #24
                    Originally posted by Sunking View Post

                    That would be a very low efficiency window shaker with an EER 10,000 BTU's / 950 watts = 10.5. As low of efficiency as Uncle Sam will allow made. Double the cost and equipment of a 5K unit. A 5th wheel trailer is not insulated like a home office setting out in the broiling Sun.

                    It would take a minimum 1500 watt panel to run off solar for a hour or two around noon. You would have to have at least a 12 volt 1000 AH battery or 24 volts @ 500 AH. Either way is a 700 pound $2000 battery. for just a few hours of cooling. Good luck with that.
                    Fair enough.

                    Due to the part of the country I live in some form of A/C is a required. For instance, today it is 106 degrees where I live and it's 100+ for much of the 200 mile surrounding area where we often camp. If I can't even run a portable A/C unit, let alone a roof mount, then I can't do much boondocking without a noisy and expensive generator. That my defeat the purpose of doing a solar installation in the first place. Maybe I just got a little overly ambitious wanting to add solar because I believe in it so strongly.

                    BTW, Sunking I just checked the specs of the unit and you were spot on with the energy rating. Here is the unit I have:
                    http://www.sears.com/royal-sovereign...p-04274902000P
                    Last edited by Tap2112; 07-08-2017, 07:43 PM.

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                    • #25
                      Originally posted by Tap2112 View Post
                      BTW, Sunking I just checked the specs of the unit and you were spot on with the energy rating. Here is the unit I have:
                      http://www.sears.com/royal-sovereign...p-04274902000P
                      Well thanks, but knowing how to calculate EER is grade school math formula EER = BTU / Watts. Just from that formula you can rewrite:

                      BTU = Watts x EER
                      Watts = BTU / EER

                      Now think about this. What if EER = 25, and BTU = 10,000. How many watts for the same cooling? 10000 BTU / 25 = 400 watts.

                      Goberrment mandates lowest EER of a air conditioner is 10. That means the unit you are looking at is the most inefficient model money can buy. You get what you pay for. I understand Hot Climates. Spent most of my life in TX, NV, and OK. Now I live where it never goes below 55, and never warmer than mid 80's in Panama. However with the humidity, mid 80's can get uncomfortable. We also get a lot of rain. Just about every day in wet season in the mornings or late afternoon. Does not last long. Dry season rains twice a week briefly in the mornings.

                      MSEE, PE

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                      • #26
                        I've put two small RV solar systems together, both have 100w panels and PMW controllers one on each of our RV's. They allow us to run my wifes c-pap, the roof vent most of the night and lights, the fridge is propane while boon docking. For the power you are needing I would look to one of the new very quiet generators, weight, cost and setup would be much easier, I doubt if you could even hear it with the AC running.
                        Last edited by AWS; 07-13-2017, 11:23 AM.

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                        • #27
                          [QUOTE=Tap2112;n353548]Thank you guys for your responses...



                          It doesn't have to be that big for the RV but in order for the system to be reasonably functional at home I would need a large inverter and charge controller(s) so I guess the RV system size was merely a function of sunk cost in all the rest of the equipment, especially since I can get the panels for $40 each. One added note, the original owners of our 5th wheel replaced the refrigerator with a household unit - all electric, no propane - so I have 290 continuous watts and 690 peak that would always be on the system when we are in transit or boondocking.

                          Additionally, many of the places we camp are 95+ degrees in the summer (last weekend it was 106 at our campsite but fortunately we were staying at an RV park) so it would have to be big enough to run our portable 10,000 BTU air conditioner. I'm not sure 300-600w of power would be sufficient to keep the batteries charged for a long weekend in that environment. My 6-9 panel guesstimate was to make sure we had enough power for everything else after fridge and A/C were satisfied. Also, the used panels are now more than 8 years old so they are not putting out 165w anymore. The controllers would need to handle the original open current specs but real life output I'm sure will be down about 10%.



                          Hi Tap: I can tell you from experience that 300 to 600 wouldn't be close to being enough for what you want. I do know a little bit about RV Solar though. In the winter with a few clouds you will be cut in half. I have two 435 watt SP panels that I can tilt on my Class A, works nicely for now. In the winter you really need that tilt. With as many panels you want most likely you will have some in the shade. Another friend has 12 older panels on his, he gets shade spots.When we go out for 10 days or so we have plenty of power for what we want right now. In two years we'll go on the road for long stretches. I have 4 extra panels 2 in case anything goes wrong and two more that will go on top before we're full time off grid. I know people who live off grid with 2000 watts and many with 350 or so, one of my best friends does it with about 350. He's very conservative with his power. I like the Idea of the residential fridge too, if my 4 door propane fridge dies I'll do the same.

                          I really like using the big panels with high voltage, less drilling into the roof, less panels, smaller wire, ect. I lose much less than 1% to the controller but lose 2-3% more in the conversion from high voltage to low voltage. If you live out west in a low humidity area you might want to try a evap cooler they really do work, my friend has a couple. We never use our 6k generator while dry camping. I don't see any panels going over 1 dollar a watt most are much less. GL
                          Last edited by Mrchinup; 07-14-2017, 01:33 AM.

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                          • #28
                            Originally posted by Mrchinup View Post

                            Hi Tap: I can tell you from experience that 300 to 600 wouldn't be close to being enough for what you want. I do know a little bit about RV Solar though. In the winter with a few clouds you will be cut in half. I have two 435 watt SP panels that I can tilt on my Class A, works nicely for now. In the winter you really need that tilt. With as many panels you want most likely you will have some in the shade. Another friend has 12 older panels on his, he gets shade spots.When we go out for 10 days or so we have plenty of power for what we want right now. In two years we'll go on the road for long stretches. I have 4 extra panels 2 in case anything goes wrong and two more that will go on top before were full time off grid. I know people who live off grid with 2000 watts and many with 350 or so, one of my best friends does it with about 350. He's very conservative with his power. I like the Idea of the residential fridge too, if my 4 door propane fridge dies I'll do the same.

                            I really like using the big panels with high voltage, less drilling into the roof, less panels, smaller wire, ect. I lose much less than 1% to the controller but lose 2-3% more in the conversion from high voltage to low voltage. If you live out west in a low humidity area you might want to try a evap cooler they really do work, my friend has a couple. We never use our 6k generator while dry camping. GL

                            Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.

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                            • #29
                              Originally posted by Tap2112 View Post


                              Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.
                              Spoken like a true believer. Off grid will always be more expensive then grid tie users. The cost difference goes up if the usage is high. My guess is that batteries will be hard to justify for a while so the best way to save is to find ways to reduce your electrical usage and match your system to that lower number.

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                              • #30
                                Originally posted by Tap2112 View Post


                                Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.
                                Well said and very true. Just in battery cost alone you are paying 5 to 10 times more than just buying power. Used in an RV, camp site or other part time use like a hybrid system can be 100 times more expensive. So if anyone is considering going off grid to save more or lessen their CO2 foot-print is only fooling themselves as that is impossible with off-grid.

                                MSEE, PE

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