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  • Complete noob to solar power

    I have been lurking on here trying to educate myself on solar energy systems, and instead have only became more confused. Hopefully someone can just steer me in the right direction to get the information I need. I have a small 12x14 cabin for camping. I would like to have enough energy to power a small box fan at night, a small water pump used occasionally to draw water from a barrel (small amounts. Brushing teeth and so on) and a couple light bulbs. Because this is a campsite used twice a year, and is not very secure, I want to spend the absolute minimum I need to accomplish this in case it is all stolen.

    How big of a system would I need for this? What is the best, simplest, most affordable and most manageable way to do this for someone completely inexperienced in this sort of project?

  • #2
    Originally posted by John Morrison View Post
    I have been lurking on here trying to educate myself on solar energy systems, and instead have only became more confused. Hopefully someone can just steer me in the right direction to get the information I need. I have a small 12x14 cabin for camping. I would like to have enough energy to power a small box fan at night, a small water pump used occasionally to draw water from a barrel (small amounts. Brushing teeth and so on) and a couple light bulbs. Because this is a campsite used twice a year, and is not very secure, I want to spend the absolute minimum I need to accomplish this in case it is all stolen.

    How big of a system would I need for this? What is the best, simplest, most affordable and most manageable way to do this for someone completely inexperienced in this sort of project?
    Hello John and welcome to the neighborhood.

    Before anyone can design a system you need to know how many kWh the system need to provide for, and only you will be able to work that out. Now if your loads are very small as it seems they might and your looking to spend as little as possible you might be best of with a small generator and battery that you can take home with you when you leave.

    Im not a system designer so I cant really help you any more than that but there are others around the place that know more than me so hopefully someone will pop into help you out. Cheers

    Comment


    • #3
      Originally posted by solar pete View Post
      Hello John and welcome to the neighborhood.

      Before anyone can design a system you need to know how many kWh the system need to provide for, and only you will be able to work that out. Now if your loads are very small as it seems they might and your looking to spend as little as possible you might be best of with a small generator and battery that you can take home with you when you leave.

      Im not a system designer so I cant really help you any more than that but there are others around the place that know more than me so hopefully someone will pop into help you out. Cheers
      A generator is out of the question unfortunately. It is a family owned campground and running motors are prohibited.

      I have no idea how to determine how many kWh I need. I do not own the fan, the lights or the water pump as of yet, and would purchase them to go along with the system. I am just a little lost on where to start. There are some packages on Amazon that do 200 watts for a reasonable price, but I have no idea if that is enough.

      Comment


      • #4
        How long is your stay at the campground ? You may be better off just bringing a battery with you, and charging it up at home. What do other folks do there ?

        $$$ of solar gear for 3 days twice a year is a lot of $ sitting doing nothing the rest of the time.
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment


        • #5
          Originally posted by Mike90250 View Post
          How long is your stay at the campground ? You may be better off just bringing a battery with you, and charging it up at home. What do other folks do there ?

          $$$ of solar gear for 3 days twice a year is a lot of $ sitting doing nothing the rest of the time.
          We stay for about a week each time. Most of the rest of the family just roughs it lol. I am just trying to make my wifes stay a little more pleasant for her since she isn't as big into camping as I am.

          Comment


          • #6
            Originally posted by John Morrison View Post
            How big of a system would I need for this? What is the best, simplest, most affordable and most manageable way to do this for someone completely inexperienced in this sort of project?
            Any solar system starts out by figuring out how much power you are going to use over time, doubling the size of the battery to support that load, and then if you want to continue on using solar, you figure out how much panel you need to support that battery, taking solar-insolation into account for your geographical location. Add multiple days of autonomy and the system becomes larger.

            It is best to break it down into bite-sized chunks first. Let's start out with one of your load requirements with a real world recommendation..

            Box fan - Endless Breeze dc fan. Basically a high-quality RV fan in a box enclosure. Pulls 1A on the low setting. Great fan for real-world use. Much better than trucker fans or computer-fan hacks.

            Lets say you want to run that for 8 hours. That is an 8a drawn total for your desired time period.

            Since you don't want to run a battery down further than 50%, you would need at least a 16ah battery capacity, assuming you are going to recharge it the next day. BUT, if you run it on the medium setting, that pulls about 2A, so to support 8 hours, (16ah total drawn) you would need double the battery calculated or about 32ah. Concorde's smallest Sun-Xtender agm would work well for just this load.

            LIGHTING: a 50 watt equivalent CFL bulb (which pulls about 1/4th the wattage that an incandescent does), running from an inexpensive MSW ac inverter, pulls a little over 1A from the battery. Again, do you want to run this bulb for 8 hours? If so, that is ANOTHER 8ah you need to add to your load total, and like before, double your battery capacity rating to twice your load.

            But we can't really go on much further until we know how many hours a day you intend to operate say both of these, and how many days "twice a year" really means. Two days? Two weeks? And critically, we need to know the geographical location (general is ok) to see what your solar insolation hours are. These hours center around noon, and are NOT sunrise-to-sunset hours.

            If you can break out your calculator and figure out how much current you intend to draw over time each day, that will help a lot. Find out how much that pump pulls, and of course how long you are going to run it.

            Comment


            • #7
              Originally posted by PNjunction View Post
              Any solar system starts out by figuring out how much power you are going to use over time, doubling the size of the battery to support that load, and then if you want to continue on using solar, you figure out how much panel you need to support that battery, taking solar-insolation into account for your geographical location. Add multiple days of autonomy and the system becomes larger.

              It is best to break it down into bite-sized chunks first. Let's start out with one of your load requirements with a real world recommendation..

              Box fan - Endless Breeze dc fan. Basically a high-quality RV fan in a box enclosure. Pulls 1A on the low setting. Great fan for real-world use. Much better than trucker fans or computer-fan hacks.

              Lets say you want to run that for 8 hours. That is an 8a drawn total for your desired time period.

              Since you don't want to run a battery down further than 50%, you would need at least a 16ah battery capacity, assuming you are going to recharge it the next day. BUT, if you run it on the medium setting, that pulls about 2A, so to support 8 hours, (16ah total drawn) you would need double the battery calculated or about 32ah. Concorde's smallest Sun-Xtender agm would work well for just this load.

              LIGHTING: a 50 watt equivalent CFL bulb (which pulls about 1/4th the wattage that an incandescent does), running from an inexpensive MSW ac inverter, pulls a little over 1A from the battery. Again, do you want to run this bulb for 8 hours? If so, that is ANOTHER 8ah you need to add to your load total, and like before, double your battery capacity rating to twice your load.

              But we can't really go on much further until we know how many hours a day you intend to operate say both of these, and how many days "twice a year" really means. Two days? Two weeks? And critically, we need to know the geographical location (general is ok) to see what your solar insolation hours are. These hours center around noon, and are NOT sunrise-to-sunset hours.

              If you can break out your calculator and figure out how much current you intend to draw over time each day, that will help a lot. Find out how much that pump pulls, and of course how long you are going to run it.
              Thank you so much for the response. As someone who has worked in a technical field, I understand how difficult it is to answer someone's questions who doesn't have a firm grasp on the concept. I will do my best to answer anything I can.

              1. Location: Southern Ohio.
              2. Time period: Memorial Day and Labor Day
              3. Length of stay: 1 week each time
              4. Time to run fan: 8 hours a day
              5. Time to run lights: 4 hours a day
              6. Time to run pump: 2-5 minutes a day.

              The lights can be low wattage, as they are not intended to be reading lights, but just a light so that the interior of the cabin is visible, and one outside would be nice too. I was looking at the 15w Flicker Flame bulbs, but again, this is just daydreaming as I have no idea if this is possible. I will purchase whatever fan is best for this application, as it is the most important. The water pump will be ran only for brushing teeth or rinsing out a dish, and will be ran less than 5 minutes a day. Something like: http://tweetys.com/par-water-pump-w-...yTgaAupB8P8HAQ

              I am unsure how to calculate this, and I apologize for my ignorance.

              Comment


              • #8
                Go to an RV shop, and look for a water pressure pump for a camper bathroom sink. That will let you brush your teeth. Also while there, look for some LED cabin lights, a 2w LED will be pretty bright. Fan, I don't know about, but that will be the energy hog, and will be the size factor for your battery. 10 hours of 2 LED lights (40 Watt hours) is only about 4 amp hours out of a 12V 90Ah deep cycle battery. 5 minutes of pump use daily might be another 5 AH consumed.
                Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                solar: http://tinyurl.com/LMR-Solar
                gen: http://tinyurl.com/LMR-Lister

                Comment


                • #9
                  Nice - good detail for us to get in the ballpark at least.

                  1. Location: Southern Ohio.
                  2. Time period: Memorial Day and Labor Day
                  We're talking about 4 hours of solar insolation per day, that is about from 10a to 2p to have any meaningful charge, despite the fact it may be light enough to see from 6a to 6p ! more later near the end ...

                  3. Length of stay: 1 week each time
                  What we'll do here is just the bare minimum for 1 day charge / discharge. Normally you plan on several day's worth of autonomy in case of bad weather, and this naturally means a much larger and more expensive system. It all depends on how critical autonomy is to you. But for this, we'll assume perfect conditions every day. Remember we're ballparking it right now.

                  4. Time to run fan: 8 hours a day
                  5. Time to run lights: 4 hours a day
                  6. Time to run pump: 2-5 minutes a day.
                  Endless Breeze fan on LOW, 1a so 8ah total so far.
                  15w flicker bulb, or 15w cfl bulb, either run through an ac inverter, about 1.5a when you figure in losses. So, 1.5 * 4 = 6ah.
                  DC pump 5 minutes a day. I see the spec for the one you are looking at is 1.6ah, so that would be pretty negligable. About 130ma per day. This would be in the small misc category so let's just say .5a for extended brushing.

                  Grand total needed per day: 8 + 6 + .5 = 14.5 ah.

                  Double your battery capacity to twice this value - 29ah battery. A common size near this would be something like a Concorde SunXtender PVX-340T rated at 32ah.

                  SOLAR - but now, the question is, what size panel do I need to recharge what I've used up (and a little more for losses) in only 4 "solar-insolation" hours? (not the dusk to dawn light period ..)

                  A 100 watt panel could accomplish this in 4 hours. A 100 watt panel can produce under BEST conditions about 5.5a. In 4 hours, that would be able to put back 22ah, and since you are only using 14.5ah per day, we are definitely in the ballpark. We are also talking just a simple pwm controller too, just to keep things on the inexpensive side. More capable controllers for more cost are available and discussed elsewhere. A Morningstar Sunsaver SS-12V 10A pwm represents good quality compared to the junk you find in most kits.

                  So this is how it is done more or less. Run the Endless Breeze for 8 hours on the middle-setting which draws 2ah, instead of the low speed at 1ah, and you'll need to double your battery capacity again. And make your panel power 200 watts. Or, if you can stand the glow and look of led lighting, you can conserve energy there as well dropping the battery capacity and panel needs back. If your budget allows, I'd suggest a 200 watt panel and an upgrade to the PVX-560T. I'm not trying to be TOO battery specific, but just using Concorde as an example agm.

                  Of course, if the sun doesn't shine, then this battery will get you through only one night and that will be that. Want 5 days of no-sun operation. Open wallet - it can be done, but see if just this day-by-day under perfect operations might be too much for the budget when you buy all this stuff. Panel / controller / battery / fan / inverter / lights / pump etc.

                  HINT: 12v is fun for this kind of temporary stuff, but for permanent year round operations drawing more than just a fan and a light, go higher voltage, like 24 or 48v. Don't paint yourself into a corner building a huge 12v system, and blow your budget when a higher voltage system is called for. Just something to keep in the back of your mind.

                  Comment


                  • #10
                    Thank you!

                    So for example, with a kit like this, would I just need the battery?

                    http://www.amazon.com/Renogy-Solar-P...1AD0F6C82BRNYJ

                    Comment


                    • #11
                      That would do it as a good learner / starter setup.

                      Don't forget that you also need an extension from the panels to the charge controller, which is located very close to the battery. It is usually 10 gauge or so for about 30 foot run. I see that Renogy put in some good tips for the new user on how to hook it all up.

                      Speaking of which, I'm assuming you are ground mounting this, but if you are thinking of rooftop, you may need a professional installer / inspection to keep your insurance in good stead, and also to make sure you simply don't burn the cabin down. Ie, laying them on the roof or other improper mounting is a fire hazard. Keep all shadows from crossing the panels for any length of time, and that includes tall grass if ground mounted.

                      Hook it all up in the backyard before you go so you can get familiar with the CC settings, how to set it for AGM and give the battery a full charge before leaving.

                      Heh, pretty soon you'll be looking at an A.R.B. fridge/freezer that also runs frugally on dc power.
                      Last edited by PNjunction; 07-29-2015, 12:20 AM. Reason: typo

                      Comment


                      • #12
                        Originally posted by PNjunction View Post
                        That would do it as a good learner / starter setup.

                        Don't forget that you also need an extension from the panels to the charge controller, which is located very close to the battery. It is usually 10 gauge or so for about 30 foot run. I see that Renogy put in some good tips for the new user on how to hook it all up.

                        Speaking of which, I'm assuming you are ground mounting this, but if you are thinking of rooftop, you may need a professional installer / inspection to keep your insurance in good stead, and also to make sure you simply don't burn the cabin down. Ie, laying them on the roof or other improper mounting is a fire hazard. Keep all shadows from crossing the panels for any length of time, and that includes tall grass if ground mounted.

                        Hook it all up in the backyard before you go so you can get familiar with the CC settings, how to set it for AGM and give the battery a full charge before leaving.

                        Heh, pretty soon you'll be looking at an A.R.B. fridge/freezer that also runs frugally on dc power.
                        It will be roof mounted, but insurance is a non issue. I will have to do some digging to find a proper installation method. Thanks so much for your help.

                        Comment

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