Planning for an upgrade

Options
1235»

Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #122
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    3. Install two 15A breakers in the epanel and connect each of the existing 12/2 cable runs to the breakers. Install small 2/4 circuit subpanels in each of the cabins and distribute the power.

    I agree with NorthGuy that this is the best way. How will you do the grounding at the two cabins? At 50 ft distance the two cabins should probably have their own ground rods.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #123
    Options
    Re: Planning for an upgrade
    vtmaps wrote: »
    How will you do the grounding at the two cabins? At 50 ft distance the two cabins should probably have their own ground rods.

    --vtMaps

    That's a very good question - and one that I hadn't considered until now. I'm open to suggestions :blush:
    · Share on Twitter
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #124
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    I'm open to suggestions :blush:

    By all means put a separate ground rod at each building for lightning purposes. But if you are running power from the same inverter or generator to both cabins, you also must run a bonding conductor between the two rods and/or an Equipment Grounding Conductor between the two cabins to provide a return path for fault currents to ground. Otherwise the breaker may not trip and thus cause a hazardous situation.
    SMA SB 3000, old BP panels.
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #125
    Options
    Re: Planning for an upgrade
    inetdog wrote: »
    By all means put a separate ground rod at each building for lightning purposes. But if you are running power from the same inverter or generator to both cabins, you also must run a bonding conductor between the two rods and/or an Equipment Grounding Conductor between the two cabins to provide a return path for fault currents to ground. Otherwise the breaker may not trip and thus cause a hazardous situation.

    I'm not sure I completely follow.

    For the bonding conductor, I would connect a ground wire of some sort between the ground rods at each of the cabins, thus completing a triangle of grounding between all three sites. I think I get this.

    Where would the Equipment Grounding Conductor connect to and what is the diifference? You say and/or in your post, so I'm assuming there is a difference.

    Thanks

    -Jerry
    · Share on Twitter
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #126
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    I'm not sure I completely follow.

    For the bonding conductor, I would connect a ground wire of some sort between the ground rods at each of the cabins, thus completing a triangle of grounding between all three sites. I think I get this.

    Where would the Equipment Grounding Conductor connect to and what is the diifference? You say and/or in your post, so I'm assuming there is a difference.

    As I understand grounding, I think the best way is to run #6 bare copper wire between all ground rods. At each cabin, connect the green wire bus (in the circuit breaker box) to the ground rod. Do NOT bond the neutral bus in each cabin's circuit breaker box to the green wire bus (except at the inverter, there should be a neutral-ground bond).

    I admit I am a bit uncertain about code requirements if you are running your power cables (hot & neutral) through conduit... I think code requires a green wire in the conduit. If that is so, the #6 bare in the trench with the conduit is redundant with the green wire in the conduit.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #127
    Options
    Re: Planning for an upgrade

    I must admit that I'm still rather fuzzy.

    The runs from the epanel to each cabin are 12/2 direct burial cable. At the Epanel end, the ground wire in the 12/2 will be connected to the ground bus bar, which in turn, will be connected to a ground rod. At the cabins, the ground wire from the 12/2 will be connected to the breaker box ground lug which will be connected to a ground rod.

    So, it sems to me that all three ground rods will already be interconnected. Would there really be a need to run another wire between the cabin ground bars?
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #128
    Options
    Re: Planning for an upgrade

    Different resistance in the length of wires.

    If all grounds are tied together in the electrical wiring and then rely on one ground rod at one location the resistance in the ground wire between that location and the furthest point from in in the ground wiring may be high enough that the grounding is no longer safe; there is still Voltage potential due to the wiring resistance.

    Add grounding rods at the separate locations and this problem is eliminated but another one crops up: ground loop potential. This can occur for the same reason: difference in resistance in wiring, and in the grounding potential between the different rods. The solution there is to tie the rods together with their own wiring, causing them to act as a single point ground. It is sometimes hard to understand that the term does not refer to a single rod in the ground, but rather what is electrically effective as a single rod in the ground: multiple rods tied together in this manner act as one larger (longer) rod.

    Yes, it's complicated. Yes, you can get multiple opinions on it. Yes, it won't ever even show up unless something goes wrong.

    If I say "we really need some grounding diagrams for reference here" someone else will ask me to draw them, won't they? :p
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #129
    Options
    Re: Planning for an upgrade

    Thanks 'Coot - I THINK that I've finally got it.










    Oh yeah, do you think that you'll have those drawings ready by suppertime? :cool:
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #130
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    Thanks 'Coot - I THINK that I've finally got it.

    Great. Now can you explain it to me? This stuff has been giving me headaches for fifty years! :p
    Oh yeah, do you think that you'll have those drawings ready by suppertime? :cool:

    Sure. Good thing you didn't specify which day. Or year. :D
    · Share on Twitter
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #131
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    Thanks 'Coot - I THINK that I've finally got it.
    Two things that seem to cause the greatest problem for people trying to understand grounding are:
    1. Thinking that two electrodes connected to "ground" are really connected to the same place, (if something is injecting current into the earth nearby, that voltage can appear on your "ground")and
    2. Thinking that the voltage on a ground electrode will be zero with respect to the nearby soil potential even when current is running through the electrode (that is, assuming zero resistance.)
    SMA SB 3000, old BP panels.
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #132
    Options
    Re: Planning for an upgrade

    One of the pictures that ought to be drawn would depict the ground wiring as a resistor, with one end anchored to Earth and designated zero Voltage potential. Then a short introduced at some point which would have maximum Voltage potential. Along the way any supplemental conductor introduced (i.e. some unfortunate sod touching the bloody wire) can have less resistance than the designated pathway and thus become energized. The goal of grounding circuitry is to avoid that. This is usually done by insuring the resistance is low enough that if a short develops anywhere along it the current protection is tripped and power is interrupted making the whole thing safe to touch.

    The theory is easy. The practical application confuses everyone, including engineers.
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #133
    Options
    Re: Planning for an upgrade

    Speaking of pictures 'Coot, I've had my supper and am eagerly awaiting those diagrams. ;)

    Thanks for for further clarification to the both of you.

    -Jerry
    · Share on Twitter
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #134
    Options
    Re: Planning for an upgrade
    Cariboocoot wrote: »
    The theory is easy. The practical application confuses everyone, including engineers.

    They say that you can make almost anything foolproof. But it is harder to make it engineer-proof, and almost impossible to make it physicist-proof.

    -- A Physicist
    SMA SB 3000, old BP panels.
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #135
    Options
    Re: Planning for an upgrade
    inetdog wrote: »
    They say that you can make almost anything foolproof. But it is harder to make it engineer-proof, and almost impossible to make it physicist-proof.

    -- A Physicist

    Huh! Try making it "Wiles proof" if you really want a challenge! :p
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #136
    Options
    Re: Planning for an upgrade

    Just a little update...

    The new system is more or less up and running. I purchased four 232AH US Batteries (US 2200XC2) to go with the system and have them wired up as a 24V bank.

    I ended up putting a 150A Blue Sea Battery Terminal fuse on the bank just in case I have a whoops moment while working on the batts. The inverter seems to have an acceptable no load draw of 0.34A, and while I haven't really taxed it yet, it does run my 10A circular saw without a hitch.

    On the epanel, I installed 3 X 20A AC breakers for load distribution. From my power shed to two of the cabins, I have 12/2 wire to carry the loads. In one of the cabins, I installed a small subpanel with 4 15A breakers. I'll do the same with the other cabin, but haven't had time. All of the cabins are now running AC CFL and LED lighting.

    On arrival, the SG in two of the batts was at ~1.255 and the other two were at ~1.265 All are now at 1.270+ (100% SOC according to US Batteries)

    I think that I still need to work on tweaking the settings on the Classic; I'm currently running at:
    Absorb - 29.4V, 3 hrs Max absorb time, and end amps of 3.0
    Float - 26.1V
    EQ - 30.6V
    I've got the charging amps limited to 23A.

    The charge voltages and amp limits are per the US Battery spec.

    I need to beef up my grounding situation. I could only get the rod down four feet before hitting bedrock, so I've been thinking about burying some bare 6AWG copper, but not sure that it will help.

    I brought my camera up with me this past weekend to take some pics to share, but then forgot to take the pictures (yet another senior moment :p).
    · Share on Twitter
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #137
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    I think that I still need to work on tweaking the settings on the Classic; I'm currently running at:
    Absorb - 29.4V, 3 hrs Max absorb time, and end amps of 3.0
    Float - 26.1V
    EQ - 30.6V
    I've got the charging amps limited to 23A.

    The charge voltages and amp limits are per the US Battery spec.

    Don't be afraid to let the current get a bit above 23 amps... especially if the batteries are cool... like in your winters when you need to get it while you can.

    About US Battery specs... All "identical" batteries are a little bit different from each other. The manufacturers test their batteries and come up with charging specs that will assure that nearly 100% of their production will not sulfate if you follow their specs. Your batteries in your situation may not require the recommended charge specs. You may find that you can back off a little bit on the absorb voltage and/or absorb time. You may find that your end amps can be higher than 3.0. Your hydrometer tells you what to do. If you can reduce the charging voltage and time without sulfating your batteries, they will last longer.
    Rybren wrote: »
    I need to beef up my grounding situation. I could only get the rod down four feet before hitting bedrock, so I've been thinking about burying some bare 6AWG copper, but not sure that it will help.
    It will help. Dig a trench as deep and as long as you can (towards a wetter area if possible).

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #138
    Options
    Re: Planning for an upgrade

    vt,

    Thanks for the thoughts and advice.

    I do know that I'll need to adjust the settings, but the hard part is being at the camp for more than 2 days in a row. It's difficult to see what's going on. There's no internet service, so monitoring via My Midnite or some other method is a non-player.

    FWIW, the cabin is currently 3-season, weekend use, so my system will be spending the majority of its time in Float with the inverter breaker off and no DC loads. It'll just be looking after the battery and CC self-consumption.

    Cheers

    Jerry
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #139
    Options
    Re: Planning for an upgrade

    For grounding, you can also get Ground Rated flat copper plates and bury them at least 18 inches deep (I assume you should bury them below the frost line). And they are not too large--Perhaps you can make a hole with a post hole digger (hand or machine).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #140
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    so my system will be spending the majority of its time in Float with the inverter breaker off and no DC loads. It'll just be looking after the battery and CC self-consumption.

    If there are no loads other than controller self consumption, I would dispense with the float. You don't want to hold battery voltage any higher than necessary or any longer than necessary. The main purpose of float is to allow your charge controller (rather than your battery) to power your loads after the batteries are charged.

    Some forklift battery manufacturers recommend against float... After the battery is charged there is no load until the next shift... no sense in holding an elevated voltage when there is no load.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #141
    Options
    Re: Planning for an upgrade

    Understand--And float for solar power systems is only a few hours per day anyway... Not 24x7.

    Of course, there is self discharge of the batteries... Flooded cell batteries should charged about once a month, to keep them from excessive sulfation (and early death). A small maintenance panel on the roof (at 1-2% rate of charge through a simple charge controller, or existing charge controller) should be a good start.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #142
    Options
    Re: Planning for an upgrade

    The US Batteries specs state that the batteries can be floated at 2.17 vpc (26.04V for a 24V bank) for an unlimited period of time. They don't mention whether there is anything detrimental about doing this, and I'm too new to know.

    Bill, thanks for the thoughts on a plate. I've never seen them in the big box stores. I may have to try an electrical supply house.

    -Jerry
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #143
    Options
    Re: Planning for an upgrade

    float is to maintain the battery at 100% soc and its purpose isn't so much for the availability of pv power to be allowed to pass to the loads, but rather that is more of a side benefit of a float charge. float charges can also be of a cyclic nature rather than continuous as some inverter/chargers and ccs do. i prefer this cyclic action over a continuous one to avoid some battery problems from the long term continuous charge.
    · Share on Twitter
  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #144
    Options
    Re: Planning for an upgrade

    Someone posted here that constant floating damaged his batteries, but I cannot find this post ...
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #145
    Options
    Re: Planning for an upgrade
    NorthGuy wrote: »
    Someone posted here that constant floating damaged his batteries, but I cannot find this post ...

    Not really important for off-grid PV systems as Niel said. The float will only be for however long the panels can maintain it during the last of the daylight hours.

    This can be a problem with stand-by power on grid-connected systems, but is usually solved by turning the float Voltage down to a minimum. AGM's will stand sustain float better than flooded cells.

    And of course batteries are going to die eventually no matter what you do, you can only hope to delay that as much as possible.
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #146
    Options
    Re: Planning for an upgrade

    Well, I hope to retire soon and spend a lot more time at the camp, so hopefully exessive floating won't be an issue :p

    'Coot, I believe that you are running the same batts as me. Do you limit the charge amps?

    Thanks,

    Jerry
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #147
    Options
    Re: Planning for an upgrade
    Rybren wrote: »
    Well, I hope to retire soon and spend a lot more time at the camp, so hopefully exessive floating won't be an issue :p

    'Coot, I believe that you are running the same batts as me. Do you limit the charge amps?

    Thanks,

    Jerry

    Yes, same batteries and yes I have an End Amps programmed (includes supplying for average load draw at the time of finish). Total Amps limit isn't a problem with only 700 Watts of panel. But the AC charger is maxed at 25 Amps - no worries.
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #148
    Options
    Re: Planning for an upgrade

    Thanks for continually sharing your wealth of knowledge.
    · Share on Twitter
  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    #149
    Options
    Re: Planning for an upgrade

    Hey Jerry,

    By any chance do you a few pic's of the finished set up? just trying to wrap my head around how all the components fit together and I find it helps to have a visual.

    What did you end up using for mounts for your array?

    Chris (from RP)
    · Share on Twitter
  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #150
    Options
    Re: Planning for an upgrade

    Hi Chris,

    Small world - Reefing and solar! Good to see you.

    Unfortunately, I kept forgetting to bring my camera to the camp and didn't snap any pictures before closing it up for the season. I'll have to wait until spring now.

    I have my panels on a frame made up 2x6 PT rails mounted to 10" diameter cedar poles. The mounting brackets are made from galvanized steel angle iron and I have a rubber membrane between the iron and the PT wood, and between the panels and mounting brackets.

    The guys on this forum are the best and most helpful that I've seen anywhere. Keep picking at everyone's brain and don't buy anything until you know what you want and have checked it out with the guys here.

    Jerry
    · Share on Twitter

Categories