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  • Solar on a budget

    Ok, so I am on a tight budget but I live 10 miles from the nearest utilities. Currently my power is provided by a generator and 2 60watt solar panels and 1 marine battery. I am trying to figureout where my investment should go. So here is wat I am thinking, I would appreciate if any of you more experienced folks could let me know if this is the best thing for me to do:

    I can invest a small amount into my solar every month (around $300USD). So I am thinking the most important part is the battery bank. I mean I know 60 wats does not produce much, but if I can build up my battery bank to my end goal of 5 total batteries, the 60 watt panel will keep me in power since the rest of the batteries will be charging while 1 is being used.

    I figure that once I get the battery bank complete, I can invest in more panels and add 1-2 100 watt panels to the system each month. That of course includes the cost of the panels and other components (I already have a 20 amp charge controller and 1500 watt pure sine wave inverter).

    My ultimate goal (at least at this time) is a 2000W system, which is about double my current calculated usage. I am planning for weather conditions and for grwth. But we are very low power users.

    So any advice would be appreciated and if you need clarification on anything, let me know.

  • #2
    If you are eventually heading for a 2,000 w system, then plan on making the switch to 24V.
    What are your AC Loads, how small of an inverter will run all your common loads. The smaller the inverter, the less parasitic loss it has,
    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

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    • #3
      Well, I have calculated my heaviest load at any time (all devices running) to be around 950W. So I doubled that to 1900 and rounded up to 2k. So I m thinking I need an inverter rated 1k-1500w

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      • #4
        Originally posted by wpmasterdesign View Post
        Well, I have calculated my heaviest load at any time (all devices running) to be around 950W. So I doubled that to 1900 and rounded up to 2k. So I m thinking I need an inverter rated 1k-1500w
        First using Solar and Budget in a sentence is an Oxymoron.

        Example a 1500 watt Inverter has minimum support requirements that must be met. It requires the system to be 24 volt battery, It requires the 24 volt battery to be at least 500 AH. A 500 AH battery requires at least a 40 Amp Charge controller with a 1000 watt Solar Panel. But there is another catch. Add one more panel requires another Charge Controller because a 40 amp MPPT Controller can only input 1000 watts at 24 volt battery..

        Another catch is you cannot use old and new batteries together. So forget your budget, you chose to go solar and that means no limit on budget.
        MSEE, PE

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        • #5
          Originally posted by wpmasterdesign View Post
          I can invest a small amount into my solar every month (around $300USD). So I am thinking the most important part is the battery bank. I mean I know 60 wats does not produce much, but if I can build up my battery bank to my end goal of 5 total batteries, the 60 watt panel will keep me in power since the rest of the batteries will be charging while 1 is being used.
          You can't buy batteries one at a time. I'd recommend saving that $300 a month until you can afford a better system, then doing it all at once. Off grid solar is NOT amenable to incremental upgrades.

          I figure that once I get the battery bank complete, I can invest in more panels and add 1-2 100 watt panels to the system each month.
          If you are doing it in sections, get a good charge controller and one full string of panels FIRST. Then add strings as you grow. Get a controller that can both handle the eventual power you want, and can handle an output change from 12 to 48 volts. That will get the best remaining capacity out of your battery bank.

          Then after you have saved enough, replace your entire bank at once. Your best price point is likely to be T105 6V flooded batteries. I'd recommend getting 8 (about $1000, or 4 months savings) for a 48 volt system. You can configure it for 12V for a short time until you can afford a new inverter, although this won't be great for battery life.

          Alternatively (probably better overall) wait until you can afford new batteries and inverter together.

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          • #6
            Listen to jflorey2. He is correct. You can't build a solar / battery system in stages. The technology requires the hardware to be "balanced" and does not work well by just adding components like batteries and panels.

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            • #7
              Thank you all for the really great advice! Now here is something else I am considering.

              recently ran across an idea and wonder what you guys might think about it. I got the idea from a guy on youtube who does it this way, and his power usage is triple my own. He says he has been doing it for years this way, and he has at least 6 years of videos to back that claim.

              The idea is a modular setup. So rather than building one larger array to provide all of my power, set up small solar "modules". Each module powers a limited number of devices and consists of the following:
              1-2 batteries $100-220
              1 60-100w panel $75-100
              1 400w inverter $20-40
              1 20 amp charge controller $15-30

              The advantage I see here is that I can have one compact setup in my shed/home office to power my computer, monitor, and printer. I can have 1 setup in my 447sf home to power my wifes laptop and charge our 4 mobile devices, and I can easily build additional units as needed since cost per unit is around $200 on the low end, $400 on the high end.

              I wont need these units to power any lights as I already have several solar lights to cover our needs there.

              Our heat is provided by wood. Cooking by propane. We dont own or want a tv, we watch on the computers. Here is everything we CURRENTLY use power for:
              Lights (covered by independently powered solar lights though)
              2 laptops (Only plugged in when charging, avg 4hr/day/laptop)
              1 Laser printer, plugged in avg of 30 minutes a week, only when in use
              1 19" LCD monitor, on 8-10 hours a day when I am working
              2 tablets and 2 phones (again, only plugged in when charging)

              None of these ever stays plugged in when not in use.


              Again, any thoughts on this would be greatly appreciated.

              I do understand your points about the budget, but it is what my income allows. So I have to work with it. As for "waiting till you can afford the full setup", that means running my generator 8-10 hours a day at a cost of $5/day x 30 days + 150, and that does not include changing the oil every 2 days because the manufacturer suggests changing the oil after 25 hours of use. And all that is of course ongoing monthly cost. Whereas solar, once it is setup costs very little to maintain.

              I am not cheap, if I could afford to drop thousands of dollars at once into my system, I would gladly do so. But I don't have the income for that and frankly, my credit sucks. And government grants and whatnot are not viable options because you have to put the money out of pocket THEN they rebate/reimburse you for a portion.

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              • #8
                Based on today's solar technology and the associated costs the only way to save money would be to install a grid tie system. If you add in batteries you will never save enough to make it economical. The cost to generate electricity from batteries will be much more expensive the just purchasing it from your POCO even if you have to run that power for a very long distance.

                The best way to save is just use less. Reduce you electrical footprint and it will cost less to run what you really need. That is the cheapest way to quickly save money on your electric bill.

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                • #9
                  Sorry, but I can't agree with that. I have checked, getting power run to my location will cost me $27,000, add at least $10,OOO to build a grid-tie system that meets the POCO standards, we are now at $37,000 (minimum)
                  Solar power costs are dropping, and are expected to continue doing so. As I said early on in this thread, we are already extremely low power users, especially compared to the American average household. We use under 2kwh/day while the average American household uses more than 30kwh/day. If I go with my modular model and each setup costs under 300, that is a total of under 600 invested. replace the 4 batteries every 5 years, and other basic upkeep that's under 600, for a total of 1200 every 5 years.
                  My mom was complaining about her electric bill a few weeks ago because it costs her over $200/mo. so in 6 months, she spends more than I will in 5 years.Even if you account for possible failures like batteries or solar panels failing, I will still save thousands over what my mom pays and well over 25K from just the UPFRONT cost of running the grid out here, add a monthly bill to that and whoa.
                  Besides, I moved off grid for a reason. Why the hell would I want to have the grid come to me???
                  Last edited by wpmasterdesign; 04-21-2017, 09:25 PM.

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                  • #10
                    Originally posted by wpmasterdesign View Post
                    The idea is a modular setup. So rather than building one larger array to provide all of my power, set up small solar "modules". Each module powers a limited number of devices and consists of the following . . . .
                    The problem there will be overdischarge, which kills batteries. Either you have to overspec each system hugely (which means lots of $$$) or you will be running one system down close to zero while another system is close to fully charged. That will quickly kill your batteries in the heavily used system. If you instead had one larger system, you'd be running it down to 50%, which batteries are OK with.

                    I do understand your points about the budget, but it is what my income allows. So I have to work with it. As for "waiting till you can afford the full setup", that means running my generator 8-10 hours a day at a cost of $5/day x 30 days + 150, and that does not include changing the oil every 2 days because the manufacturer suggests changing the oil after 25 hours of use. And all that is of course ongoing monthly cost. Whereas solar, once it is setup costs very little to maintain.
                    Solar costs a lot to maintain in terms of batteries. Overall a generator is probably going to be cheaper - mainly because solar power systems still need a generator.

                    OK how about this instead. Wait until you can afford a good inverter/charger at an appropriate voltage (24 or 48 volts; I prefer 48.) Get lousy (cheap, used) batteries to provide that voltage. They will die very quickly - but you'll be saving up for your real batteries during that time. Once you have those batteries, then you have a system that will greatly cut down on your generator usage (i.e. run it once every 3-4 days for 8 hours instead of every day.)

                    THEN start on solar. Start with a good charge controller with your existing panels, then add strings as you have money to do so.
                    I am not cheap . . .
                    Neither is solar! It works if you are willing to pay for it. If not, you will tend to be disappointed. There aren't many "clever shortcuts" that will give you a robust system without spending the money on it,

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                    • #11
                      Well I agree that at only 2kWh/day you are definitely using very little so maybe living off grid is something that you will be able to handle.

                      Just try to understand that whatever way you do it any system you build will have to be a stand alone and sized exactly for a specific set of loads. I would not try to combine the systems but you will need to keep an eye on the batteries and be careful not to discharged them more than 25% for each cycle or they will not survive long.

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                      • #12
                        Originally posted by jflorey2 View Post
                        The problem there will be overdischarge, which kills batteries. Either you have to overspec each system hugely (which means lots of $$$) or you will be running one system down close to zero while another system is close to fully charged. That will quickly kill your batteries in the heavily used system. If you instead had one larger system, you'd be running it down to 50%, which batteries are OK with.


                        Solar costs a lot to maintain in terms of batteries. Overall a generator is probably going to be cheaper - mainly because solar power systems still need a generator.

                        OK how about this instead. Wait until you can afford a good inverter/charger at an appropriate voltage (24 or 48 volts; I prefer 48.) Get lousy (cheap, used) batteries to provide that voltage. They will die very quickly - but you'll be saving up for your real batteries during that time. Once you have those batteries, then you have a system that will greatly cut down on your generator usage (i.e. run it once every 3-4 days for 8 hours instead of every day.)

                        THEN start on solar. Start with a good charge controller with your existing panels, then add strings as you have money to do so.

                        Neither is solar! It works if you are willing to pay for it. If not, you will tend to be disappointed. There aren't many "clever shortcuts" that will give you a robust system without spending the money on it,
                        Over discharge is not really an issue as I have a voltage monitor connected at all times, which has an alarm that will alert me when the battery hits 11.9.
                        For my low pwer consumption, my batteries are just $75/ea and ea will last 5 years. Pretty cheap in my mind. Running a gen as much as I would need to would mean replacing the gen every 1-2 years. So thats 300-400 ea time.
                        I think your idera would be good IF I used more power. But I use a very small amount of energy so my modualr systems are low cost (under 300 ea) and each will last 20+ years, except batteries.
                        I dont NEED a "robust" system. Read the entire thread, and you will see that. I need to produce less than 3kjkwh/day/ One of my modular systems does more than half of that.

                        And it is not about being unwilling to spend the money, it is about living within ones means. I realize solar is not cheap, I am not that naive. However, the alternatives are not really more cost effective over time. Right now, I spend 50ish bucks a month to maintain my generator (fuel, oil, etc). That's 600 a year. My 5 year cost for these solar modules is 1200, or under 3 years of generator. And if I have to replace my gen, that cost doubles.
                        Last edited by wpmasterdesign; 04-21-2017, 10:43 PM.

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                        • #13
                          Originally posted by SunEagle View Post
                          Well I agree that at only 2kWh/day you are definitely using very little so maybe living off grid is something that you will be able to handle.

                          Just try to understand that whatever way you do it any system you build will have to be a stand alone and sized exactly for a specific set of loads. I would not try to combine the systems but you will need to keep an eye on the batteries and be careful not to discharged them more than 25% for each cycle or they will not survive long.
                          Yes Suneagle, you are correct regarding needing to design each module for specific loads. But at the same time, they will be more scalable than a larger system. If I ever need to add more capacity, I can add more panels or more batteries easily because they are not interconnected via a bank or array. Rather I use 1 battery down to the 11.9 (80%) mark, then switch to another that is fully charged. Besides, although I do not know what the future might hold, at this point, I do nto imagine my power needs growing by all that much.
                          As for monitoring, I will have voltage monitors connected to each, with an alarm set to go off when the battery hits 11.9. Plus, the entire set is disconnected from the battery when not being actively used. But I agree, it will be essential to be vigilant in order to et maximum life.

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                          • #14
                            Originally posted by wpmasterdesign View Post
                            Over discharge is not really an issue as I have a voltage monitor connected at all times, which has an alarm that will alert me when the battery hits 11.9.
                            Right. But if you still want to get good use out of the system, then you will either have to turn it off early or greatly oversize it. One larger system will tend to average your loads. Have a day you have to get a lot of work done on the laptop? You'll either drain small system #1 system to zero, or have to stop working on your laptop, or have to oversize it. Having a party for someone?* Then you will have to drain small system #2 to zero, or party in the dark, or have to oversize it.

                            Whereas if you have one larger system, it will handle both events just fine at a lower cost per watt-hour.
                            I think your idera would be good IF I used more power. But I use a very small amount of energy . . . .
                            So give us a number in watt-hours per day.
                            so my modualr systems are low cost (under 300 ea) and each will last 20+ years, except batteries. I dont NEED a "robust" system. Read the entire thread, and you will see that. I need to produce less than 3kjkwh/day/ One of my modular systems does more than half of that.
                            "Robust" means it works even when the weather isn't great, or you forget and leave a light on for an extra hour, or you have an unexpected load.

                            Obviously you can do whatever you want. But I think you will be happier overall with a good (single) battery system, a good (efficient/reliable) inverter/charger, and solar added as you can afford.

                            (* - I have no idea if you ever have parties, or ever have to get a lot of work done on a laptop. But almost no one's use per load is perfectly constant.)

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                            • #15
                              Originally posted by wpmasterdesign View Post
                              Rather I use 1 battery down to the 11.9 (80%) mark, then switch to another that is fully charged.
                              Don't do that. Keep all batteries connected, so that all batteries work together to keep average charge levels high. Nothing is worse on a battery than discharging it - then disconnecting it for a while until you get a chance to recharge it. Also, while most parts of a solar power system are protected against accidental short, batteries are not - they are the most dangerous part of the system and should not be connected and disconnected often. Plus, disconnecting/reconnecting batteries often leads to high resistance connections, with the resulting risk of poor performance, overheating and fire.

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