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Off grid partially mostly used for power outage usage. Why won't it pay for itself??

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  • Off grid partially mostly used for power outage usage. Why won't it pay for itself??

    Well, First off I would like to say hello to all. Secondly I will give all the information on what I have and what I am doing so it will make it easier.. My system is setup on a gentrol controller as I can switch from line to solar/backup. I cannot get natural gas and LP is to expensive for my taste so a generator is out and that is why I have come to install a solar backup. I put it on a gentrol controller because I want to use it even when the power is on to save money and I can control what runs off of it and to get by alot of redtape this makes it alot easier. I run basically all my LED lights and tv/radios/laptops and all my plugs except high drain areas like bathroom and kitchen. . My equipment is as follows:

    2 - RENOGY® 250W Watt Monocrystalline Black Solar Panel UL Listed
    1 - Renogy 40amp mppt
    8 - 6V batterys 24V config
    1 - Go Power! GP-SW3000-24 3000-Watt Pure Sine Wave Inverter (hard wired)

    Yes I know I am short 6 panels and a better charge controller or another 40amp no need to go there!!!


    I want to add 6 more panels to this setup to be able to take care of the higher draw areas and still charge the batteries if needed 450AH. I can runall my led lights /tv/laptops and plugs and still charge the battery to full by the end of the day.

    So far this system has lowered my bills on average $40 - 80 and is working good (when i say system I mean conservation additions aswell). This is on a homemade tracker. This system was cheap to install about the same as a lp/diesel generator with a transfer box professionally installed and has dropped my usage dramatically even though it is small at this point. With what little I am using and saving by solar and good management why is it people say it will not pay for itself. After I add the extra panels/charge controller the system will pay for itself in about 2 years...... Yes I know batteries fail.... but if not dropped below say 85% on a regular basis and good care why would I not be able to make it back and pay for new batteries in the life expectancy of them.

    Thanks
    Joe

  • #2
    What batteries are you using?

    Most manufacturers should provide documentation as to how many cycles you get (discharge/charge) at 20% DOD. Lets say that this is 2000 cycles or 5 years. However your batteries will last to their full chronological age if they are only cycled for power outages. Lets say that this is 10 years. So you can calculate the cost of your batteries for 5 years and compare to the rate your utility charges you. You can ignore the rest of the expenses you have for your other equipment as you want them anyway for backup purposes. In this contrived example, if you pay $500 for 4 batteries two times in 10 years instead of one time in 10 years you can calculate what you would have paid per kWh for just what you power from those batteries. It would not be accurate to count your conservation as that could have been done anyway.

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    • #3
      Well I paid $600 for 8 batteries as it is a 24v bank. They are

      Model: Group Size EGC2
      Item #:347631
      •20 amp hour rate:230
      •5 amp hour rate:174
      •6 amp hour rate:178
      •BCI Group Size:GC2
      •Minutes at 25 amps:448
      •Minutes at 75 amps:120
      •Volts:6

      Why would I not add in the conservation additions as that was part of the whole deal. Otherwise I never would have. If I am more conscious because of the solar it should be added just like any other cost savings for schools or what not. It all adds to the length of the batteries and drain on the system does it not? I am pulling an average amperage AC wise with lights/TV/laptops of 2 amps when fridge and freezer kick in intermittently I go to about 7 amps total. I use DC inverter compressors on my refrigeration equipment and switching to constant pressure DC step up well pump. The draw on these on startup is minimal and RLA is minimal. Even the Furnace blower is modulating DC.

      The savings is I am licensed in all mechanicals and do HVAC/refrigeration/Journeymen plumber and starting Apprentice electrician. I do not know it all but I sure want to learn that is why I am here asking. Batteries is my biggest downfall. You can read alot of opinions on how long batteries last and what the life expectancy is. I know little but what I have read.

      Obviously I do not consider 220V important so I would not add that to my total wattage needed. We use wood burning stove/bbq grill for cooking if power is out and live on a land filled with natural springs for water.

      I think I may have set myself up for buying batteries before I knew all the facts and I accept that. I am doing this more as a fun project and to learn so don't be to harsh

      Comment


      • #4
        Originally posted by Stix View Post
        Well I paid $600 for 8 batteries as it is a 24v bank. They are

        Model: Group Size EGC2
        Item #:347631
        •20 amp hour rate:230
        •5 amp hour rate:174
        •6 amp hour rate:178
        •BCI Group Size:GC2
        •Minutes at 25 amps:448
        •Minutes at 75 amps:120
        •Volts:6

        Why would I not add in the conservation additions as that was part of the whole deal. Otherwise I never would have. If I am more conscious because of the solar it should be added just like any other cost savings for schools or what not. It all adds to the length of the batteries and drain on the system does it not? I am pulling an average amperage AC wise with lights/TV/laptops of 2 amps when fridge and freezer kick in intermittently I go to about 7 amps total. I use DC inverter compressors on my refrigeration equipment and switching to constant pressure DC step up well pump. The draw on these on startup is minimal and RLA is minimal. Even the Furnace blower is modulating DC.

        The savings is I am licensed in all mechanicals and do HVAC/refrigeration/Journeymen plumber and starting Apprentice electrician. I do not know it all but I sure want to learn that is why I am here asking. Batteries is my biggest downfall. You can read alot of opinions on how long batteries last and what the life expectancy is. I know little but what I have read.

        Obviously I do not consider 220V important so I would not add that to my total wattage needed. We use wood burning stove/bbq grill for cooking if power is out and live on a land filled with natural springs for water.
        Your Sam's club batteries are only warrantied for 1 year. So you need to budget for worst case $600 per year for batteries. How much would it cost you to use the grid for what those batteries power at 15% DOD?

        Comment


        • #5
          Well if I was to calculate a worst case 1 year savings at this rate it would be $600. Basically a break even. But they should last far beyond one year. I have the DTE savings difference since I added solar let me go look. Dam smart meters.

          Comment


          • #6
            Originally posted by Stix View Post
            Well if I was to calculate a worst case 1 year savings at this rate it would be $600. Basically a break even. But they should last far beyond one year.
            Savings - break even. Experience - priceless

            Comment


            • #7
              Originally posted by lkruper View Post
              Savings - break even. Experience - priceless
              Agreed

              Here is the differnce seen so far minus the 6-12 to 6-16 as that was my sons grad party and 3 campers on site using A/C's and power turned off solr used grid.

              2.jpg1.jpg

              Comment


              • #8
                Originally posted by Stix View Post
                Agreed
                If I buy 8 Sam's club batteries to use like you do, what would you charge me to warranty them for the second year?

                Comment


                • #9
                  Originally posted by lkruper View Post
                  If I buy 8 Sam's club batteries to use like you do, what would you charge me to warranty them for the second year?
                  I would not until I see how they do Also how do I know you did not abuse them........ Like I said I spend that much on frivolous things. I attached from when I did have panels to when I did not look in last post. I did it backwards but you can see the difference besides the sons grad party day and family RV's here using my power.

                  Comment


                  • #10
                    Simple answer is IF you could utilize every possible watt hour you could store in a battery, every day before they turn into a boat anchor, you would pay at least 4 to 7 times more than buying from the POCO. It is just simple math and physics.
                    MSEE, PE

                    Comment


                    • #11
                      Originally posted by Sunking View Post
                      Simple answer is IF you could utilize every possible watt hour you could store in a battery, every day before they turn into a boat anchor, you would pay at least 4 to 7 times more than buying from the POCO. It is just simple math and physics.
                      His premise is a bit different. He must have the backup and so is backing out all the equipment needed to charge the batteries. So if he looks at just the cost of the batteries alone, he breaks even.

                      I even made him calculate a 1 year life expectancy because of the 1 year warranty.

                      His 8 230 AH batteries cost $600. At 15% DOD that gives him 50 kWh per year. $600 / 0.12 = 50 kWh.

                      Comment


                      • #12
                        That is correct. But it is 460 AH as I had to do it even though it is not recommended. I did not go three strings though as it would not be needed for the necessities. I use it for the small things that add up over time but make sure the batteries stay charged and drain them down to 80% once every 2 weeks. During the day the sun keeps the battery in float and runs the small stuff.

                        Comment


                        • #13
                          Originally posted by Stix View Post
                          If I am saving roughly 65 bucks a month. I could buy the batteries every year and be ahead.
                          Next year you get core back

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                          • #14
                            Originally posted by lkruper View Post
                            Next year you get core back
                            Good point! But seriously for my own knowledge on batteries. How long do you think they "should" last in this situation? Like I said I do not believe all I read. Like putting a desulphater (spelling) on makes them last 15 years yada yada What is the scoop from all the ones using these on systems. Trying to be tongue and cheek to have fun but learn in the process.

                            Would 6 more panels be to much for this setup and battery Ah? I can transfer more power if uneeded to a Electric water heater 100% efficiency there!! Also add more circuits when needed through gentrol during the day when sunny and timed to go off and back to grid at night or when incoming voltage drops below a certain level as in cloudy days from the panels to controller(in a certain time period as to not go off if only 5 minutes). This is the only way I can see to save money as the cost of energy is more during the day here and cheaper at night. Only makes sense to me and the way to come out ahead.

                            Comment


                            • #15
                              Originally posted by lkruper View Post
                              His 8 230 AH batteries cost $600. At 15% DOD that gives him 50 kWh per year. $600 / 0.12 = 50 kWh.
                              Wel in the USa you can buy a Kwh for 12 cents. That same battery you ar eusing has a calander life of about 2 years. So if you use it only for emergency say once a week that Kwh cost jumps to $3.50/Kwh. A generator and gas is much less expensive and does not have a low demand factor. With a battery you cannot cook or cool/heat your home or cook. Genny no problem.
                              MSEE, PE

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