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  • Advice on getting power 250ft to batteries

    Hi to everyone. My name is Gord I am new, and would like to get a bit of advice regarding the best way to configure and how many panels you recommend, for my 250 ft run from panels to the charge controller, for an off grid system. I have a couple other questions I threw in as well. I will first apologize because I know I will get a bit wordy. I hope a few of you will read thru, and give me some layman advice. My reason for being wordy, is because I have read others give partial, incomplete info, that has resulted in various questions coming back at them.

    This is a new 930 sq ft cabin/house at a 1/4 section of land in North central Alberta, latitude 54 degrees +-. Because it is new, everything is and will be high efficiency, including the wood stove. We have had this get away for many years, without the benefit of grid power, and don't plan to get on the grid now. By default we have become very good at conserving energy of all sorts. My wife and I have built 7 houses ourselves in the past, (when we were younger) and have learned how to source materials, and sub contractors. Before power it will be complete for about 1/3 of the price of hiring a builder, and everyone who worked on it left very happy. Our finances demanded that we do it ourselves.

    For the next 6-7 years this will primarily be a 3 season retreat, when we have plenty of sun, with maybe a weekend or 2 each month in the winter. In 6-7 years our use will go up, and I will upgrade batteries, inverters etc as needed then. We have a very high efficiency wood stove for primary heat, and wood galore, We have most appliances, heat, and hot water on propane, we will be putting in a small electric fridge for occasional use, but have a propane fridge as well. I have roughed in everything from the hot water tank, furnace, and all appliances for both electricity, and gas. Every light installed is at or under 10 watts. Our other electrical use will be very efficient. I have done a use calculation numerous times, and we will be under 5000 watt hrs per day during heavy use, which wont be daily.

    A bit about my install.

    1) I have a good friend who is an electrician, who has worked industrial, commercial, and residential. He has done a few off grid residential installs in the past, and will install mine. He took a solar workshop, a few years back, to do remote stuff for the company he works for. Someone else designs, then he installs. He does not want to determine, my component needs, but will make sure the small details including remote, and onsite monitoring etc will be done correctly. I think that's fair. If I'm going to have the system I should learn some and continue to learn about it. I could press him but won't, he works enormous hours over the winter, in camps and such, then takes lot's of time of in the nice weather months up here.

    2) I have a 300 ft length of 6 awg underground cable that I would like to use. I bought it as new scrap for $100 from one of the projects my friend was working on. I was hoping to get 4 awg but I couldn't pass this up. I am hoping done properly I can make this work. I have gone online and learned some about resistance. My real required length is about 235 ft end to end, but I am using 250 ft for a base length. The reason for the long run is to prevent shading from trees, to have panels and expansion without cluttering near the cabin. We also get direct south exposure, with a big snow cover field to help with reflection in the winter. This is the closest suitable spot.

    3) I can get what I think is a good price on 10 new, Canadian Solar KuDymond 340 watt poly panels @ 50 cents a watt, 35 cents US bucks, I am unfamiliar with these split panels, but am hoping I can use these to start then add to later if or when we need. 340 watt, VMP 38.4 volts, IMP 8,86 amps. I'm pretty confident that wiring everything in series would work with 6 awg very easily, but don't think the charge controller will like it much. I am not too concerned about a little extra or less wire, my buddy gets it cheap, and he is installing for free. Him and a couple other friends use the place too. It's great for all of us. Greater security, and they help out, whether we are there or not. I do wonder if tigo optimizer will help with partial shade from clouds, and if they are worth the extra $500 or so they would cost me?

    4) I can also buy good quality lead carbon 12 volt 200 or 250 ah batteries, at cost from the company my friend works for. (His brother in law is an electrical engineer, and very senior person at the company) They use a lot of batteries for remote monitoring, rail, and mining, etc. I am thinking about starting with 4-12v-250 ah batteries, and think I can keep them down to 50 to 60% DOD, or under for most use. The cycle life, and cold weather suitability, along with cost in a no maintenance battery is directing me to these. I also think that in the next few years companies like Nant and others are going to bring battery prices down, and longevity up. If nothing else I will up grade my complete battery bank with lead carbon down the road.

    5) We are going to have a back up propane generator. I have a little 3000 honda that supplied all the power to build the cabin, and for our use to date, it will handle tools, and may handle back up if I convert it to propane, and can make it work with a back up switch.

    It appears that the money we can save vs retail on cable/wire, panels, batteries, and install will put us in a decent up front cost position. I think I can save on racking, and maybe other components too.

    Again I apologize for all the words. Here are my questions.

    a) can someone please help me configure the above mentioned panels, and/or recommend others? to work with the 48v 250 ah battery. From late spring to early fall, I'm not overly concerned, but from late fall to early spring I am due, to our big decrease in sun hours. I want to configure with a focus on the lower winter hours, while using the backup gen in a less is better fashion. I just can't wrap my head around configuring the volts and amps in order to both run 250 ft, and charge the battery as quick as possible.
    b) can I use a morning star/tristar 60 amp charge controller? If not please recommend other then midnight solar.
    c) will this work with a 48 v 4000 inverter or less? We expect to go bigger when we retire. I may be wrong but I have also read that inverters do not have the longevity of solar panels, so I prefer to not overbuild too much just yet.

    I will source the components as cost effective as I can, and our ROI, is not the biggest concern right now, but it looks like it could be pretty good. Part time power for the next 6 to 7 years is the priority. The power company quoted us $32,000 to hook us up, 3 years ago it was $17,000, which I thought was ridiculous then for the same thing. They obviously don't care about normal inflation. Then approx $125 per month in various service charges before using any power, which goes up every year. $9000 + in the next 6 years, before we even turn on a light bulb. $12,000 to $15,000, is more likely with power use. The price of power is also going up considerably year over year. Bare bones $44,000 in the next six years, then I'm very sure $3000 bare minimum to who knows what, every year after. $100,000 for power for 20 years use is very possible. I know I can do better. The technology, and I think the prices for solar will be better and more cost effective, in the years to come. The grid is not an option, we won't do it.

    Thanks for reading, I hope some of you with knowledge chime in.

    Gord

  • #2
    I need to follow up on cable length. I wrote wrong. My real world actual cable run will be maximum 220 ft. with 12 ft out of ground on each end for hook up to charge controller, and panels. I know the 30' changes things somewhat.

    Gord

    Comment


    • #3
      You need to consider voltage drop in the 250' wire run, because of the energy lost to I2R heating in the run. To minimize the energy lost you need to minimize the current as well as reduce the resistance of the wire. Because of the I2 the factor with the most influence is the current. So you want the DC voltage to be a high as possible.
      But if you go much beyond 80 volts you may see reduced efficiency in the Charge Controller.
      If the panels will be partially shaded during the high production hours around noon, you definitely want to use optimizers or else short strings with approximately equal shading within each string. If only one or two panels will be shaded you can probably do well enough by depending on the bypass diodes in each panel. You do not want to parallel partially shaded and unshaded strings if you can help it.
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

      Comment


      • #4
        Here is one thing to consider. Your solar energy comes in big lumps mid day, your use is probably
        spread over time at a much lower level. SO it would be most efficient to place the batteries near
        where the panels need to be, so the peak power level can be carried efficiently to them. Your long
        run then may be at a lower, longer interval power level. Could even be a 120VAC or 240VAC
        inverter you remotely turn on, minimum current. Bruce Roe

        Comment


        • #5
          Originally posted by bcroe View Post
          Here is one thing to consider. Your solar energy comes in big lumps mid day, your use is probably
          spread over time at a much lower level. SO it would be most efficient to place the batteries near
          where the panels need to be, so the peak power level can be carried efficiently to them. Your long
          run then may be at a lower, longer interval power level. Could even be a 120VAC or 240VAC
          inverter you remotely turn on, minimum current. Bruce Roe
          On the other hand, especially in winter, having the batteries and electronics 230 feet from the cabin may be a serious disadvantage.
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

          Comment


          • #6
            Originally posted by inetdog View Post

            On the other hand, especially in winter, having the batteries and electronics 230 feet from the cabin may be a serious disadvantage.
            For sure, a trade off against the price of copper. My panels are 500 feet from the house, I need to snow blow
            a path back there on a regular basis. Bruce Roe

            Comment


            • #7
              Originally posted by bcroe View Post

              For sure, a trade off against the price of copper. My panels are 500 feet from the house, I need to snow blow
              a path back there on a regular basis. Bruce Roe
              Your case may be the same as the OP where the location of the panels is based on the optimum insolation.

              Comment


              • #8
                Originally posted by Ampster View Post

                Your case may be the same as the OP where the location of the panels is based on the optimum insolation.
                It isn't.

                Comment


                • #9
                  Originally posted by J.P.M. View Post

                  It isn't.
                  Perhaps I should have used the word "maybe". Can you give me the particulars? Or should I wait for bcroe to respond to a post that was directed at him
                  Last edited by Ampster; 02-18-2019, 12:53 AM.

                  Comment


                  • #10
                    Originally posted by Ampster View Post
                    Perhaps I should have used the word "maybe". Can you give me the particulars? Or should I wait for bcroe to respond to a post that was directed at him
                    I respect Bruce and I'm quite sure he can speak for himself. Take what I write as background or do with it what you wish, including ignoring it.

                    But as you ponder what to do about what you may consider my impudence, also think about your question. If you do, you might come to the conclusion that most everyone else who's knowledgeable in such areas has reached as a matter of common sense: For any location that's shade free, when considering fixed or at least fixed azimuth arrays, there is one azimuthal orientation that optimizes annual insolation and probably a second (probably close to but not the same) azimuth orientation that optimizes annual system output. The case of seasonal tilts may help, but azimuth will stay fixed.

                    Finding optimum array orientation has been one of, if not the primary driving force behind modeling of solar energy availability and resource assessment for solar energy systems. "I want to know the best orientation for my collectors" is a phrase that's been around for a long time. That implies one orientation unless dual axis or gimbaled tracking is considered. Bruce's are fixed azimuth arrays of several orientations. For the majority of locations, that optimal azimuth is probably within 10-15 degrees of true south (or north in the southern hemisphere). Bruce has several orientations capable of variable tilts, most of them quite a ways off south, with some of them at 90 or 270 deg. azimuths. Now Bruce may have different opinions about this, but unless conditions are very unusual, any array with a 90 or 270 deg. azimuth, including his, for the same panel and panel areas he will never have as much annual insolation or annual system output as an equator facing array tilted at close to local latitude. Other considerations besides maximizing output may be part of the design process, and that seems lot of where Bruce's ideas are centered on, but your statement "Your case may be the same as the OP where the location of the panels is based on the optimum insolation" is, to the best of my knowledge incorrect. Or, if that was Bruce's intention, he got that part of it wrong.

                    Now I'm sure Bruce has a good time with his stuff, and I listen very carefully to what he has to say about EE matters as he knows much more about such things than I. In such areas I think he has a lot of correct information, a rare common sense approach and experiential knowledge. But in the area of resource assessment and optimizing collector orientation to maximize either annual insolation or annual output, I know more than some, and I know Bruce's stuff does neither - and I've told him that in the past, long before you showed up here, both by forum postings and PM's when they were still available. I just gave up ranting to him about it several years ago, figuring he either was ignoring me, or didn't care about it, or didn't want to get tied up in areas where he felt uninformed, or I was full of crap. Or, whatever.

                    So, before you get your knickers in a bunch and think I stuck my nose into what you may think is your private communication, know you're late to the party. Consider my comment to you "It isn't"as information you may find useful, or put it where the sun don't shine. In such things, and IMO only, and to your question, if his goal was to get systems that have either optimized annual insolation or maximum annual output, or even seasonal optimals for that matter via variable tilts, he didn't meet it. He's done a lot of very useful stuff, and I've learned from it, but optimizing output via orientation is not what's been attained.

                    Enough particulars for you ?

                    Comment


                    • #11
                      Originally posted by J.P.M. View Post
                      ........
                      Bruce's are fixed azimuth arrays of several orientations
                      ......Bruce may have different opinions about this, ....
                      Is that it in a nutshell? I hope you can work out your issues with Bruce. You are sure spending a lot of server storage on your issue with Bruce's panel orientation.

                      Comment


                      • #12
                        Originally posted by Ampster View Post

                        Is that it in a nutshell? I hope you can work out your issues with Bruce. You are sure spending a lot of server storage on your issue with Bruce's panel orientation.
                        No, it isn't. I don't deal in nutshells. And to say (write) I have an "issue" with the orientation of Bruce's panels is not correct. I do not.

                        After being at it for over 40 years, I simply know, until disabused of the idea, that for the same gross panel area, way off south and multiple panel orientations such as Bruce has built almost never maximize annual solar radiation flux on his arrays or maximize electricity production per m^2 of panel surface, and so will not maximize economic return on the investment.

                        In that sense, which is what I took to be the sense of your incompletely explained and so possibly and easily misinterpreted use of the term "optimum orientation", Bruce's arrays are not optimum.

                        But that's not a criticism of what Bruce has done. I wouldn't have done it his way, starting off with the likely fact I couldn't and can't do what Bruce has done. But, all that matters not one whit. Not one. I do some eccentric stuff with alternate energy as well and folks think I'm a bit more than simply eccentric. I bet we're both having fun even if we go about it in different ways. I believe he has, and I hope I have made substantive contributions to the body of knowledge, or at least filled in a few cracks.

                        As for my response to your question, is what it is.

                        Your cutting and pasting of my response to your request for particulars leaves a lot out.

                        You asked "Can you provide me the particulars ?".

                        I took that to mean you wanted to know (from me) the background and more detail of why I wrote "it isn't".

                        I attempted to provide that information to the best of my ability and recollection to the extent I felt it warranted for a clear response, and as I felt time and effort permitted.

                        When someone askes me a question, I try to be respectful and respond and answer the question as best as possible.

                        I'd respectfully suggest that if you reread what I wrote and follow up on any questions it sparks in you brain that you might learn some of why I have the orientation/production opinion I have.

                        Also, others reading my response might have an opportunity to see that your statement about orientation may have some holes in it.

                        This is, after all, a place to learn stuff and exchange opinions.

                        As usual, take what you want of my stuff and scrap the rest.

                        But I'd respectfully suggest if you don't like what you get when you ask a question, that you consider being more careful about what you ask for.

                        J.P.M.

                        Comment


                        • #13
                          Originally posted by Ampster View Post

                          Is that it in a nutshell? I hope you can work out your issues with Bruce. You are sure spending
                          a lot of server storage on your issue with Bruce's panel orientation.
                          Guess you have not been here long enough, to observe how many objectives J. P. M. and
                          I have enjoyed respectfully agreeing to disagree on. The original array here was hired in
                          2013, to get it done promptly and solve the paperwork hurdles. The system is out of sight
                          of the house, no solar on any of my roofs, net metering inverters in a shed.

                          This standard SW desert design in my opinion was far from optimum for the continuous
                          clouds and frequent snow here in NW ILL. Continuous observation, design, and
                          construction have been going on ever since. No argument that facing a panel south will
                          generate the most KWH, a very important consideration when panels were extremely
                          expensive. But now panels are cheap, and remember it is always going to cost more per
                          KWH at this location than in the SW. Primary considerations here have shifted to keeping
                          this max size inverter plant as loaded as possible, and to minimizing snow clearing
                          efforts and any other maintenance.

                          In getting this science project right, those objectives have been met under sun or clouds.
                          15KW of inverters producing 28,000 KWH a year is about as good as the SW desert systems
                          do, and the fixed system will easily out perform a tracker at this location. First cost is
                          higher, compensated in this case by huge doses of DIY. Snow performance is hugely
                          improved; while snow blowing some 7 inches this morning, I simply tapped on every other
                          vertically oriented panel and almost all the snow fell off, the earlier, not yet upgraded
                          arrays required significant labor to be cleared.

                          As for bragging rights, this rather conventional house has achieved ZERO CARBON
                          FOOTPRINT with all electricity and heat coming from the sun, mini-split heat pumps
                          making a huge contribution. Bruce Roe

                          Comment


                          • #14
                            Originally posted by bcroe View Post

                            Guess you have not been here long enough, to observe how many objectives J. P. M. and
                            I have enjoyed respectfully agreeing to disagree on. The original array here was hired in
                            2013, to get it done promptly and solve the paperwork hurdles. The system is out of sight
                            of the house, no solar on any of my roofs, net metering inverters in a shed.

                            This standard SW desert design in my opinion was far from optimum for the continuous
                            clouds and frequent snow here in NW ILL. Continuous observation, design, and
                            construction have been going on ever since. No argument that facing a panel south will
                            generate the most KWH, a very important consideration when panels were extremely
                            expensive. But now panels are cheap, and remember it is always going to cost more per
                            KWH at this location than in the SW. Primary considerations here have shifted to keeping
                            this max size inverter plant as loaded as possible, and to minimizing snow clearing
                            efforts and any other maintenance.

                            In getting this science project right, those objectives have been met under sun or clouds.
                            15KW of inverters producing 28,000 KWH a year is about as good as the SW desert systems
                            do, and the fixed system will easily out perform a tracker at this location. First cost is
                            higher, compensated in this case by huge doses of DIY. Snow performance is hugely
                            improved; while snow blowing some 7 inches this morning, I simply tapped on every other
                            vertically oriented panel and almost all the snow fell off, the earlier, not yet upgraded
                            arrays required significant labor to be cleared.

                            As for bragging rights, this rather conventional house has achieved ZERO CARBON
                            FOOTPRINT with all electricity and heat coming from the sun, mini-split heat pumps
                            making a huge contribution. Bruce Roe
                            Bruce: Thank you. The last word is yours.

                            Respectfully,

                            J.P.M.

                            Comment


                            • #15
                              I very much appreciate the impute, and hope for more. Some in the form of this is what I would do with the panels, would be great as well. Here is what I took into consideration for panel placement.

                              1) The storage shed for solar, and back up propane line is situated in between a 500 gallon propane tank, and the cabin, approximately 30' from each. I did consider putting the storage shed near the panels, however winter access would be more of a challenge, but not my biggest concern because I anticipate some winter snow removal from the panels. My issue with the shed near the panels was running and extra 250' +- underground propane line to the shed for a back up generator. As it sits everything fits nicely. I have a buried propane line to the cabin, and another to the shed spot for the generator. I also have the underground cable from the shed to the cabin in the ground. I also thought about just running the genset up close to the cabin, but I want to charge batteries as well, when needed.

                              2) The panel placement gives me a wide open field facing directly to the south. They will be out of the way, and I have plenty of room for expansion. With the right mounts I can tilt for snow drop off, and some reflection from snow, There are no trees, poles or anything else to cause shading from shortly after sun up, to shortly before sunset in the winter, just the clouds. Cloud shading is why I am interested in optimizers. I just don't know how much they will help with that.

                              I need to deal with the long DC run, and I am hoping the 6 awg will be ok. The tristar 60 mppt controller states an impute voltage of up to 600v, Could I not run 10 or 12 Of the mentioned KuDymond 38 volt panels all in series, or for expansion ability run 2 x 5 or 6 in series then parallel at the output 190 volts and 18 amps for 10 panels. On calculator.net using 250' of 6awg they indicate a a voltage drop of 1.87%. I think I'm missing something here. In "theory" with my very limited electrical mind, I thought 30 of these panels would be possible.

                              Gord

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