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  1. #21
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    Default Re: Grid-tied or off-grid. Please consider ...

    Last design issue

    If I want to change the Axpert in the future, I would most likely want to change the series/parallel panel configuration as well. With the Axpert, strings are mostly parallel (VOC =145V , rated current 80A).

    So, although slightly costly I thought of creating a number of "strings", e.g. connect every 4 panels would create a string (2 x parallel = 22A and 2 x serial =96V). I can then bring the 3 strings to a combiner box where I could reconfigure them to the MPPT as needed. Obviously the combiner box would have to be flexible for futures. OR should i run individual strings per panel and then at a junction box configure the strings which could then go into a DB board dedicated to string configuration and protection (fuses)

    To make use of the current Axpert I would combine the 3 strings in parallel to give me 96V/66A which is well within the inverter spec. I do not have any major big trees, so shading could be less of an issue - or am I missing something?

    Lastly, this is most probably a stop-gap configuration - I am still considering my options re the inverter but as I work through all the comments and my replies, the mud is sloowly settling.

  2. #22
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    Default Re: Grid-tied or off-grid. Please consider ...

    With your 4 panels giving 22A it seems that a combiner box close to the panels does not seem to be a good idea. Rather each 4 to a marshaling box. 66A from such a combiner box is a lot of current to take to a MPPT.

  3. #23
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    Default Re: Grid-tied or off-grid. Please consider ...

    Badly put
    The idea is to bring them all to a box within 1m from the MPPT

  4. #24
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by wims_za View Post
    So, although slightly costly I thought of creating a number of "strings", e.g. connect every 4 panels would create a string (2 x parallel = 22A and 2 x serial =96V). I can then bring the 3 strings to a combiner box where I could reconfigure them to the MPPT as needed. Obviously the combiner box would have to be flexible for futures. OR should i run individual strings per panel and then at a junction box configure the strings which could then go into a DB board dedicated to string configuration and protection (fuses)
    Here is what I ended up with.
    Combiner box is planned for 4 Series / 5 Parallel on 350w panels, yet I started with 2S / 5P.
    So with no changes to the Combiner Box, or the strings, I just tie in 2S extra per string, the wiring done on the roof between the panels.

    Hope this gives you some more water to clear the Combiner Box mud.

    Below is just a SAMPLE ito the panels in series / parallel, attempting to link the drawing to the actual combiner box. Hope you get the idea.

    I did not use fuses, but 16amp NoArk double pole breakers. Can switch each / all string off, switch one by one on if I want to test each strings production against the others.

    And I added lightning protection in too, far right of the NoArk breakers.
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  5. #25
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    Default Re: Grid-tied or off-grid. Please consider ...

    I would suggest you put your oven, geyser and airconditioners on Eskom power and run the rest of the house on your Axpert.
    Should be simple to do.

    Just as a suggestion, I too had many fridges and freezers in my house, the old types. They worked fine, but after measuring everything in the house, I found these units to consume around 4kwh per fridge/freezer per day!!! That is same as your oven for 2 hours flat out.
    So that is something to think about.
    New fridges and freezers use much less energy and the compressor start-up is also much smaller.

    P.S.
    Another thing I just heard from up north, in Tswane.
    Because so many guys have gone completely off the grid, but still have an electrical line to their property, they now starting to bill the guys 20% of the average consumption of the past 3 years!!!
    So again it does not make sense to go 100% off the grid.


    2007 Nissan Navara 4L Auto - Worshond


  6. #26
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by Wetkit View Post
    Just as a suggestion, I too had many fridges and freezers in my house, the old types. They worked fine, but after measuring everything in the house, I found these units to consume around 4kwh per fridge/freezer per day!!! That is same as your oven for 2 hours flat out.
    So that is something to think about.
    New fridges and freezers use much less energy and the compressor start-up is also much smaller.
    4kwh per day at wot R2.00 = R8.00 x 365 = +-R 3 000 pa right?
    What does a new A+ A++ fridge/freezer cost?
    And, how long will it last, compared to the fridge/freezer Granny gave us that is still working very well?

    Yes, those items do draw a lot of power versus the A+ and A++ models today.
    But we tend not "skip over" the cost to make a house energy efficient, as it costs a ton of money!

    EDIT: And going onto gas cooking, install not cheap, is a additional cost on top of the off-grid system ... and gas is not cheaper than Eskom.

    Which ties right back into the costs of a off-grid system PLUS the cost of getting energy efficient devices.
    vs
    Grid tied and getting more panels and extending the cost to make everything energy efficient right now, to when the devices actually fail.

    Just a thought to ponder on.



    Quote Originally Posted by Wetkit View Post
    P.S.
    Another thing I just heard from up north, in Tswane.
    Because so many guys have gone completely off the grid, but still have an electrical line to their property, they now starting to bill the guys 20% of the average consumption of the past 3 years!!!
    So again it does not make sense to go 100% off the grid.
    Question though, is there proof of this 20% increase? A bylaw or some such maybe? Asking because Gerrie Nel may be needed.


    CoCT embraced the solar movement, therein the ongoing court case, for they want more people on solar and legally want to buy from them ... network infrastructure dependent!
    Yeah, there is that teeny weeny ole thing, dated Munic electricity infrastructure.

    And they want this ASAP for a stable power supply to the city means more business investment from all over.
    Last edited by the_terrible_triplett; 2020/07/01 at 09:07 AM.
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  7. #27
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by the_terrible_triplett View Post
    Question though, is there proof of this 20% increase? A bylaw or some such maybe? Asking because Gerrie Nel may be needed.
    I did not say 20% increase.
    Say your bill was R1k per month for the past 2 years, you would now be billed for R200 per month, even while you not consuming anything.
    Perhaps you can see it as a "connection" fee?


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  9. #28
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by Wetkit View Post
    I did not say 20% increase.
    Say your bill was R1k per month for the past 2 years, you would now be billed for R200 per month, even while you not consuming anything.
    Perhaps you can see it as a "connection" fee?
    Apologies, you are right, you did not say 20%! My bad.

    Connection fee ... like CoCT brought in the R150 + VAT connection fee, yeah, I can buy that.

    Wonder if they did it legally, is there a by-law stating such, or just quietly added on?

    Wonder how many people have seen this on their bill, people who scrutinizes their bills each month?

    See, local electricity networks have a min cost as they have to be maintained, and with a reduced consumption it becomes a huge problem.
    At least, that was what CoCT realised and that is how they solved that maintenance cost.

    I thought it fair, the connection fee, as I took away between R1k - R1.5k pm away from them.
    Political Correctness
    Political Correctness is a doctrine, fostered by a delusional illogical minority, rabidly promoted by a unscrupulous mainstream media which holds forth the proposition that it is entirely possible to pick up a turd ... by the clean end!

    Saw this in a pub - no idea why the wife does not see it so:
    I'm not opinionated ... I'm just always right!

  10. #29
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    Default Re: Grid-tied or off-grid. Please consider ...

    Here is pic of my combiner box again. Combiner box for every MPPT. I'm running fuses in mine again. Fuse on the + and fuse on - side. 3 string going in each combiner box with 3s3p 330w pannel setup. Connector bloks in the + and - and from there isolater switch and dc surge/lightning protector.

    You will see one fuse holders are open. This one still need to get pannels. I design them so if I need to expand then i can add more. You will see how close is the mppt's to the PV combiner box.

    The dc trip switches is a great way to go like TTT did.
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  11. #30
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    Default Re: Grid-tied or off-grid. Please consider ...

    Nice to see that there are some people that is using some MicroCare products.
    Quote Originally Posted by Gerlach View Post
    Here is pic of my combiner box again. Combiner box for every MPPT. I'm running fuses in mine again. Fuse on the + and fuse on - side. 3 string going in each combiner box with 3s3p 330w pannel setup. Connector bloks in the + and - and from there isolater switch and dc surge/lightning protector.

    You will see one fuse holders are open. This one still need to get pannels. I design them so if I need to expand then i can add more. You will see how close is the mppt's to the PV combiner box.

    The dc trip switches is a great way to go like TTT did.

  12. #31
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by LdLL View Post
    Nice to see that there are some people that is using some MicroCare products.
    They make good products, and work really good but Microcare just need to step up there game. Well they started doing it now but they still lacking behind Local guys like MLT.

  13. #32
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    Default Re: Grid-tied or off-grid. Please consider ...

    Must agree. Their service levels are crappy especially if you compare them to a company like SolarMD which is available 24/7 7 days a week.

    However I can't complain about the service after level 5 lock down. Got a quote the following day after e-mailing (nogals) them and all my stuff a week later.
    Quote Originally Posted by Gerlach View Post
    They make good products, and work really good but Microcare just need to step up there game. Well they started doing it now but they still lacking behind Local guys like MLT.
    Last edited by LdLL; 2020/07/02 at 06:42 PM.

  14. #33
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by LdLL View Post
    Must agree. Their service levels are crappy especially if you compare them to a company like SolarMD which is available 24/7 7 days a week.

    However I can't complain about the service after level 5 lock down. Got a quote the following day after e-mailing (nogals) them and all my stuff a week later.
    Jy kan dit weer se van Solar MD. Die eienaar het my oor genooi na hy my DIY setup gesien het. Baie nice en state of the art stuff wat hulle gebruik. Love hoe hulle die inverters display ook wat hulle voor hulle batterye voor design.

  15. #34
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by the_terrible_triplett View Post
    Here is what I ended up with.
    Combiner box is planned for 4 Series / 5 Parallel on 350w panels, yet I started with 2S / 5P.
    So with no changes to the Combiner Box, or the strings, I just tie in 2S extra per string, the wiring done on the roof between the panels.

    Hope this gives you some more water to clear the Combiner Box mud.

    Below is just a SAMPLE ito the panels in series / parallel, attempting to link the drawing to the actual combiner box. Hope you get the idea.

    I did not use fuses, but 16amp NoArk double pole breakers. Can switch each / all string off, switch one by one on if I want to test each strings production against the others.

    And I added lightning protection in too, far right of the NoArk breakers.
    TTT

    Please advise on which CBs you used, and where you sourced them from.

    Did you do the string serial/par before the combiner box or in the box ?

  16. #35
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by wims_za View Post
    Please advise on which CBs you used, and where you sourced them from.
    16amp NoArk double pole breakers.

    Quote Originally Posted by wims_za View Post
    Did you do the string serial/par before the combiner box or in the box ?
    Combiner box is planned for 4 Series / 5 Parallel on 350w panels, yet I started with 2S / 5P.
    5 individual strings come down to the combined box, each up to 4 panels in series per string.
    Inside the combiner box they are wired for parallel as per the pic a few post previously.
    Political Correctness
    Political Correctness is a doctrine, fostered by a delusional illogical minority, rabidly promoted by a unscrupulous mainstream media which holds forth the proposition that it is entirely possible to pick up a turd ... by the clean end!

    Saw this in a pub - no idea why the wife does not see it so:
    I'm not opinionated ... I'm just always right!

  17. #36
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    Default Re: Grid-tied or off-grid. Please consider ...

    Tks TTT

    Who supplied your NoArk breakers

  18. #37
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    Default Re: Grid-tied or off-grid. Please consider ...

    Quote Originally Posted by wims_za View Post
    Tks TTT

    Who supplied your NoArk breakers
    Rubicon.
    Political Correctness
    Political Correctness is a doctrine, fostered by a delusional illogical minority, rabidly promoted by a unscrupulous mainstream media which holds forth the proposition that it is entirely possible to pick up a turd ... by the clean end!

    Saw this in a pub - no idea why the wife does not see it so:
    I'm not opinionated ... I'm just always right!

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  20. #38
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    Default Re: Grid-tied or off-grid. Please consider ...

    Tks

    Not cheap but got them today

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