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System setup: Off grid solar, w/generator backup

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  • #16
    AGM batteries have lower resistance than flooded and can charge at higher rates.

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    • #17
      Originally posted by Mike 90704 View Post
      AGM batteries have lower resistance than flooded and can charge at higher rates.
      AGM batteries also cost 2x as much, and last only half as long as flooded. Only a good choice in special circumstances.
      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


      • #18
        SD51555: Full time off grid here. I understand your desire to make this venture successful, but I think that you may have underestimated the some of the items to consider.

        1. Are you living in this cabin full time? Part time? Seasonally and for how long?

        2. Is grid power available, if so why do you want to attempt a solar powered system with batteries?

        3. What are you doing for toilet, shower and water supply?

        4. Have you taken into consideration the heating requirements of the new structure. Have you done heat loss calculations, etc. What R values are the walls, floors and ceiling.? What are the actual local costs for propane? Here at over $2.75 a gallon, limits my use of propane to the water heater, and stove/oven, and main backup 20kW generator. I use wood to heat the house. There are propane lanterns built into the walls by the original owner prior to installing electric power via generator and batteries, and later on the solar arrays, but have not used the propane lanterns. I use an electric refrigerator, but I think the specs on a full size propane fridge is about 1 gallons every 3 days or so. So what size of propane storage do you plan on getting since prolonged winter isolation may prevent winter deliveries of the propane? My sister in North Dakota has like a 2,000 gallon propane tank, while I only need a 500 gallon propane tank.

        4. I think that you are way underestimating your solar power generation and possibly your proposed battery bank. Winter production at your location with solar is practically zero for 3 months nov-jan. See the link for Lake County: http://egauge14464.egaug.es/index.html, on the purple bar, select 1y. I live in one of the best winter insolation areas of the USA, southwest New Mexico, 5.5 hours winter insolation. Lots of clear blue winter skies. My FLA battery bank weighs 1,500 pounds, and I admit it is over batteried.

        5. A 12-volt supply/distribution system may not be appropriate for the cabin. You may want to consider a 24 vdc supply with a 120 vac distribution system.

        Good luck on your project.

        Comment


        • #19
          Originally posted by citabria View Post
          SD51555: Full time off grid here. I understand your desire to make this venture successful, but I think that you may have underestimated the some of the items to consider.

          1. Are you living in this cabin full time? Part time? Seasonally and for how long?

          2. Is grid power available, if so why do you want to attempt a solar powered system with batteries?

          3. What are you doing for toilet, shower and water supply?

          4. Have you taken into consideration the heating requirements of the new structure. Have you done heat loss calculations, etc. What R values are the walls, floors and ceiling.? What are the actual local costs for propane? Here at over $2.75 a gallon, limits my use of propane to the water heater, and stove/oven, and main backup 20kW generator. I use wood to heat the house. There are propane lanterns built into the walls by the original owner prior to installing electric power via generator and batteries, and later on the solar arrays, but have not used the propane lanterns. I use an electric refrigerator, but I think the specs on a full size propane fridge is about 1 gallons every 3 days or so. So what size of propane storage do you plan on getting since prolonged winter isolation may prevent winter deliveries of the propane? My sister in North Dakota has like a 2,000 gallon propane tank, while I only need a 500 gallon propane tank.

          4. I think that you are way underestimating your solar power generation and possibly your proposed battery bank. Winter production at your location with solar is practically zero for 3 months nov-jan. See the link for Lake County: http://egauge14464.egaug.es/index.html, on the purple bar, select 1y. I live in one of the best winter insolation areas of the USA, southwest New Mexico, 5.5 hours winter insolation. Lots of clear blue winter skies. My FLA battery bank weighs 1,500 pounds, and I admit it is over batteried.

          5. A 12-volt supply/distribution system may not be appropriate for the cabin. You may want to consider a 24 vdc supply with a 120 vac distribution system.

          Good luck on your project.
          1. This will be extremely part time. It's a hunting cabin. It will see mostly weekend use (friday night to sunday morning). In fall, it may see extended stays of 4 days every other weekend. By mid november, it'll be down to me being there for weekends again, and those will be most frequent into mid December, and then maybe once per month again until spring. I've called this new building my 10-15 year building.

          2. Grid power is available, but it's expensive for what I need. It's $45/mo base charge, and then 12 cents/kW/hr.

          3. Composting toilet, no built in shower facilities, rather a 5 gallon shower bag plan. As far as potable water, I'll haul in a 5 gallon water cooler with a spigot on the bottom.

          4. Heat - I've thought it through. Because there will be no water in the building, it's not going to be heated while I'm away. I am planning to leave the pilots on though. The building will have 2" of spray foam under the floor and all the way up to the roof. I'll have a 35k BTU propane furnace in each of my cabin side and garage side. LP fridge is rated to use 8 gallons/mo (8 cubic foot new). The tank I'm looking to get is a 250 gallon. I expect that to be enough given the insulation and scarce number of winter days I'll be heating it. Propane here right now is $1.35 gallon, peaked at $1.65 this winter. I plan to pay for snow removal in the event I need extra gas. If I find that 250 isn't enough, I'll switch it out to a 500 next summer. Others in the area with a 250 can make an entire winter under my type of plan and have far larger spaces to heat with much poorer insulation.

          4b. I am worried about winter generation. I won't lie there.

          5. I'm not sure what to say about the 12 volt system. I'm modeling this after my buddy's cabin. He's had his set up this way for 18 years near St. Cloud MN and it's worked great for him. No low power days, and he's only now had to replace one battery since he installed it back in 2000.

          Comment


          • #20
            1) composting toilets often have a small 24/7 fan, and an electric heater to boil off water. Heater is a deal breaker, and must be disconnected

            2) modern power needs (laptop, phone charger, DVD) may need more PV.

            3) A smallish 2Kw - 3Kw inverter generator may fill your winter generator needs. Will the panels self-shed snow ?
            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


            • #21
              Originally posted by Mike90250 View Post
              1) composting toilets often have a small 24/7 fan, and an electric heater to boil off water. Heater is a deal breaker, and must be disconnected

              2) modern power needs (laptop, phone charger, DVD) may need more PV.

              3) A smallish 2Kw - 3Kw inverter generator may fill your winter generator needs. Will the panels self-shed snow ?
              When I say composting toilet, here's what I've got in mind. When the weather is fair, it'll be a wood box over a small hole in the ground. It'll probably take about 10-15 dukes and get covered in sawdust, back filled, and moved ahead 3 feet. During inclement weather, there'll be a tote under a box in the garage with a deep bed of saw dust. All #1's must go outside until the urinal is installed and plumbed to a weep hole outside. The property won't see maybe 30 days use per year and no more than 100 dumps. I don't want to have a massive latrine hole on my property.

              I've been going up for ten years, and haven't needed to charge a laptop, and don't plan to start. Not sure I'll even have a DVD player, as those things are going the way of the VCR quickly. I am planning on a high power antenna to pull in OTA tv. Haven't found any info on what that'll take to power.

              I'm paying cash for all of this, so some of it is going to have to come in stages. AC and generator are definitely on hold until 2019. I'm leaving my walls open for now until I am sure I'm happy with my wiring setup. And the panels will shed snow, yes.

              Comment


              • #22
                Originally posted by JohnyWalter
                We have a couple of portable generators that we can use for back-up. One is a small Honda 2000 watt generator that only runs on gasoline. The other is a dual fuel (gasoline or propane) that is about 8500 watts and I only use propane in that one.

                The Honda cost me about $1000 and the 8500 watt generator cost me only $599 when on sale at Costco. Our power went out only once last year for about 10-12 hours and I ran the propane generator overnight and it worked well but was very loud.

                I would definitely recommend a generator that either runs on propane or natural gas as those fuels do not degrade over time as gasoline does.
                Sorry Johny, you, with your fancy formatting on your generator link, just got yer self banned.

                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

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