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  1. #21
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by bees View Post
    Thanks gents.

    Which values do I use to do the calcs? I’m going to plot all options on a spreadsheet during the week to compare.

    Example of a panel:
    Canadian Solar 435w:
    VMPP:40.1 V
    IMPP:10.85 A
    Isc:11.35 A
    Voc:48.6 V

    Sunsync 5kw (6500w PV input):

    Attachment 642966

    How do I distinguish between the 370V, 500v and 425v values when doing the panel calcs? I assume I need to use the Voc of the panels, and not Vmpp? In the panel example above there’s a 11.35A value, which exceeds the 11A value on inverter? All very confusing currently, but sure I’ll be put on the right path shortly
    The 11.35A is the short circuit amps. The normal Imax is 10.85A which is below the max of 11A. At 3250W per string I think you can use up to 8 panels per single string. Although this is over 3250W the Sunsynk should limit it to 3250W for each MPPT during cloud edge if it goes over 11A.
    8x series for Voc=388V which is below the 500V you can use with a big safety margin. Try not to exceed 450V for the Voc series string.
    Last edited by ekkekan; 2022/01/09 at 10:47 PM.

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  3. #22
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    Default Re: Going solar: starting to investigate.

    Dont forget to calculate (google) the voltage drop based on the cable thickness, length and composition, include the nominal voltage of the array.
    Ideally the value should not exceed 3% - 5%.
    Otherwise upsize to 6mm2, copper, or the addition of an extra panel.
    The lower the DC voltage, the higher resistance.

  4. #23
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by rnieckau View Post
    Dont forget to calculate (google) the voltage drop based on the cable thickness, length and composition, include the nominal voltage of the array.
    Ideally the value should not exceed 3% - 5%.
    Otherwise upsize to 6mm2, copper, or the addition of an extra panel.
    The lower the DC voltage, the higher resistance.
    Perhaps the last sentence should be the higher the current the higher the volt drop. The voltage cannot change the resistance of the wires.

  5. #24
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    Default Re: Going solar: starting to investigate.

    Ohm's law includes voltage and current R = V I
    I neglected to include current in my comment as its fixed for panels in series - the string voltage is more adaptable.

    One of the reasons commercial PV systems were designed with 600-1000VDC string voltages, is to compensate for the increased resistance in longer lengths of cables required for additional panels (and higher output / value)
    Newer systems feature 1500VDC string voltages.

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  7. #25
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by the_terrible_triplett View Post
    Re. the panels. Start measuring the sqm area you have available, establish the angle and how North it is facing, then see which sized panel fits the best, in that SQM, then get MPPT to fit the panels.

    Simple as that.


    Bees, let me put it very succinctly.

    If there is one time you should not be misled, or advised incorrectly, being in Durbanville (we are around the corner from each other), then it is now. There are installers cutting corners till the site is inspected and the installer and owner can be in deep dwang. Just follow the easy to understand basic regs, and you are 100% fine, I promise.

    Anyone who advised you, and as a result you are left behind to face fines in due course, or worse, forced removal, those advisors will be far gone leaving your high and dry. Been there, seen that a few times.

    The bottom line: If you have panels on your roof, or intend installing such, then you HAVE to register them.

    Do that upfront, BEFORE you even buy one panel.



    That form you fill in, the registering, it is free. Not 6-8k ish. I can advise on that, I can suggest a engineer close to you for more succinct experienced advices, I can suggest installers, sparkies, all whom are well versed in all the T&C's of installing grid-tied / off-grid systems.

    If you opt to go grid tied, i.e. Sunsync, or any other NRS certified inverter, it will be a breeze to continue.
    If you opt to go off-grid, Axpert or what not, not a problem, but you will have it installed as off-grid with the relevant parts to have it fully off-grid. And no, you cannot use Eskom to ever charge the batteries. And if installer does that, and are reported, they, and you, can have some drama.

    The registration process is easy, free, really not that complicated, nor cumbersome and definitely not problematic. I'm dead serious, easy as falling off a horse IF you do it right the first time.

    I'm happy to guide you, to do it right.
    i fully agree on above, but also investigating, also in Durbanville, but want a power saving from grid tie, would it work as some systems cost R80 000 to install and what is the use if you have to charge the batt overnight, what is the saving on your electricity bill, over time with such or similar installation, sorry for the hijack...

  8. #26
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by bees View Post
    Thanks gents.

    Which values do I use to do the calcs? Im going to plot all options on a spreadsheet during the week to compare.

    Example of a panel:
    Canadian Solar 435w:
    VMPP:40.1 V
    IMPP:10.85 A
    Isc:11.35 A
    Voc:48.6 V

    Sunsync 5kw (6500w PV input):

    Attachment 642966

    How do I distinguish between the 370V, 500v and 425v values when doing the panel calcs? I assume I need to use the Voc of the panels, and not Vmpp? In the panel example above theres a 11.35A value, which exceeds the 11A value on inverter? All very confusing currently, but sure Ill be put on the right path shortly
    Use Voc and Isc AND the Temp Coefficient especially if you are contemplating running at max, or oversized arrays.

    Note the V temp. coeff. [%/C] and I temp. coeff. [%/C] being used for the calc on cold/hot days.

    The colder the panels are under peak sunlight conditions, or on a cold sunny day with cloud effect, can push a oversized array over the max voltages of the MPPT's, and blow them.


    A few websites I have picked up over the years:
    Shadow Calculator: http://shadowcalculator.eu/#/lat/50.08/lng/19.9
    Suncalc: https://www.suncalc.org/#/40.1789,-3...1.10/08:59/1/1
    Geographical Info System: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

    And then this one:
    Solar Angle Calculator: http://www.solarelectricityhandbook....alculator.html


    I know this is not SunSync, see if SunSync maybe has the similar calculators, if not, use these to get a feel for what is potting on panels and temps and so forth, as MPPT = MPPT = MPPT.

    https://www.victronenergy.com/mppt-calculator

    Using the custom option it will give you a ton of info on what input values are used to do calculations as an example.


    Excel calculator: https://www.victronenergy.com/upload...-Calc-4_0.xlsm

    I add the panels I want to use into that calculator, to see to where I can push the limits, uses all the values one finds on the panels, even temp coefficients.

    Unless Sunsync has same, use the above to see what is possible on the panels you want to use, to get an idea of al the factors, possibilities, for your own info.
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  9. #27
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    Default Re: Going solar: starting to investigate.

    Please do not install PV until you have City approval!
    Yes, it is a problem, but they can be full of bull.
    Had many guys have their power disconnected and given huge fines during the past year or so.

    Sunsync probably your best option right now.
    Make sure you know the capabilities of the unit. It would give you much better returns that way.

    I found having multiple strings in different directions actually give me a much flatter but longer PV production during the day.

    What I have found was that the modern type Hybrids works better with larger lithium banks. Say 3 times bigger than your daily consumption.
    This way you can still be connected to the grid and use cheaper pre-paid power when needed, but really you "off-grid".
    The batteries will support your essential loads during loadshedding but when power is connected, the batteries will also supplement your other loads, thus reducing your total draw from the grid to Zero.
    Currently I only buy R100 per month, just to keep the meter going.


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  11. #28
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by Reccepops View Post
    i fully agree on above, but also investigating, also in Durbanville, but want a power saving from grid tie, would it work as some systems cost R80 000 to install and what is the use if you have to charge the batt overnight, what is the saving on your electricity bill, over time with such or similar installation, sorry for the hijack...
    Not a hijack, a very good question.

    You NEVER charge the batts using Eskom ever.
    UNLESS you have consecutive LS events and bad weather to boot, then you use Eskom, being a ton cheaper than a generator.

    Other than that, you let the system do it's thing, software is supposed to make for optimal ROI overall.


    Points to ponder on:
    Option 1:
    Get a 3/5kva inverter, 3.5/5kw array and a smaller Ah battery bank, which can be done with Lifepo4, not so much with lead acid, as Lifepo4 can take big amps. T&C's apply though.
    Key being to keep the loads that needs to be powered off batteries during LS well within the limit of the battery bank, and NOT the 3/5kva inverter max ability.
    In other words, start with a small Lifepo4 bank.

    3.5/5kw array will happily feed the 3/5kva inverter powering the house and recharge the batts from last nights use, the focus being powering the entire house using the sun.

    Option 2:
    Versus a larger bank that one can recharge during the day offsetting even more Eskom usages during the night.

    Reason: If you have Lifepo4 bank, then you use it at night to off-set even more Eskom loads, keeping in mind the LS events.
    Political Correctness
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  13. #29
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by Reccepops View Post
    i fully agree on above, but also investigating, also in Durbanville, but want a power saving from grid tie, would it work as some systems cost R80 000 to install and what is the use if you have to charge the batt overnight, what is the saving on your electricity bill, over time with such or similar installation, sorry for the hijack...
    Or you go with like a Solis, and not bother with batteries at all.
    Political Correctness
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  15. #30
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by Wetkit View Post
    Please do not install PV until you have City approval!
    Yes, it is a problem, but they can be full of bull.
    Had many guys have their power disconnected and given huge fines during the past year or so.

    Sunsync probably your best option right now.
    Make sure you know the capabilities of the unit. It would give you much better returns that way.

    I found having multiple strings in different directions actually give me a much flatter but longer PV production during the day.

    What I have found was that the modern type Hybrids works better with larger lithium banks. Say 3 times bigger than your daily consumption.
    This way you can still be connected to the grid and use cheaper pre-paid power when needed, but really you "off-grid".
    The batteries will support your essential loads during loadshedding but when power is connected, the batteries will also supplement your other loads, thus reducing your total draw from the grid to Zero.
    Currently I only buy R100 per month, just to keep the meter going.
    Absolutely agree.

    Just one titibt to prevent disappointment for the newbies. Last winter, on many days, I got like 300w, sometimes 0 (zero) watts, for my 4.2kw array because of weather.

    Man, it breaks the spirit.
    But it also shows one very clearly on what it can costs to be off-grid totally.

    Come summer, we smile all the way ... but now Cpt seems to have thunder and some rain in summer too. Bugger.
    Political Correctness
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    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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  17. #31
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by the_terrible_triplett View Post
    Info: CoCT has a monthly fee for all connections. PAYG is cheaper per unit than if you have a postpaid meter/older meter, the one on "credit". More effort for them to read them.




    We discussed on the "Meeting of Minds" thread.

    Short version: Moment you have panels and you are connecting the panels via a DB to Eskom/Munic grid, you need to follow the SSEG installation regulations as per ones local Munic.
    Insurers are wizening up too.
    And you don't want people getting hurt, fires started, forcing some official to come and investigate/asses the damage, and ask a bunch of questions. Keep a low profile by doing it right.




    - You said it, not me.
    Your house, your equipment, your decision and, obviously, responsibility.




    YES!!! The good ones are very busy.
    More and more sparkies are entering the fray, which I think is a good move.
    The ONLY "tough" thing I think of, is mounting the panels properly for storm conditions. Not everyone is a expert at that. Rest is not that complicated to connect.




    Cpt has monthly connection fee of about R199 pm, with or without solar system.
    The moment you want to feed back, that is a whole new ballgame and that is where the costs increase per month, yes.
    Need to do those sums very carefully, as it is net metering per annum.




    Lots of guys here that can assist here with the most efficient way of doing installing the panels.
    I will jump in if I see something.
    If we meet, I can show you instead of trying to explain here.





    Yes, fill in the form with your planned array size like say i.e. 5kw array, inverter (5kva) and battery bank AH, submit that with your details completed.
    Keep the form.
    They then respond with approval, you start the install.
    Right at the end you submit the fully completed form with engineers/sparkies signatures, circuit diagram and all that.

    Personally, if you are going like Sunsynk, go grid tied from the start. Inverter is NRS certified. Nike it. (Just do it).
    All it costs more is like +-R2500 for engineers signoff and you KNOW you have it all spot on IF you use the guy I have in mind.

    Just don't feed back, not the time for that yet. HODL on that one.
    How is that PAYG is cheaper than the meter, as the monthly fee is included in the PAYG, it is a difficult one as you buy a certain amout pm. And sometimes top it up. ? I still use the old meter and believe that when installing solar, the grid tie will also work as it " reverses" the meter resulting in lower elect. Usage, whereas PAYG blocks the " reverse" current.....

  18. #32
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by Reccepops View Post
    How is that PAYG is cheaper than the meter, as the monthly fee is included in the PAYG, it is a difficult one as you buy a certain amout pm. And sometimes top it up. ? I still use the old meter and believe that when installing solar, the grid tie will also work as it " reverses" the meter resulting in lower elect. Usage, whereas PAYG blocks the " reverse" current.....
    Titbit: In CoCT, if you apply for grid-tying, you are to replace the older meters with a new PAYG meter, as wheeling, meter turning back, is illegal.
    Clever move if you ask me, as the PAYG meters cannot see the direction of the power, so it charges you if you feed back.

    For Credit and Prepaid, there is a connection/service charge of +-R194.29pm, like when you are on the Home User tariff.

    Because they don't have to come and read the meter, PAYG is cheaper per unit, than for customers on the older Credit meters.

    Interesting: Recently read that all the PAYG meters in Cpt have to have a firmware upgrade. They send you two codes to type into the meter, to upgrade it, is done per suburb.


    Found this interesting ...

    The income from tariffs is used to cover the cost of providing the service. If the City does not get the income from the tariffs, it cannot deliver the services, it stressed.

    The City of Cape Town rejected reports that it has the most expensive tariffs in the country. Far from it. Although it is not an easy comparison to make as there are different tariff bands and customer bases for all these metros, if you are supplied by the City of Cape Town, including the fixed component of the tariff, you still generally receive more units than in Joburg, especially when you use less electricity.

    For example, for the City of Joburg, the equivalent fixed charges per month is R768,21 (incl. VAT).

    This does result in lower per kWh charges, so which metro is cheaper depends completely on the amount of energy consumed again, electricity is cheaper for consumers in Cape Town who use less electricity, the metro stated.

    The fixed charge is an established part of tariffs, not only in Cape Town but also in the rest of the country, as it ensures that income is stable, irrespective of how much or how little is used, it noted further.


    https://businesstech.co.za/news/ener...d-price-hikes/
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  20. #33
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    Default Re: Going solar: starting to investigate.

    Taking into account the predicted 30% increase coming this year
    Do you need to register anything in Johannesburg when installing?
    And can you go pre paid on your supply so you can top up if needed but sit without the R768 fee that you pay for post paid systems
    Looking at the COJ R760+ service charge I am considering going pre paid meter supplied by COJ

    And then installing solar system large enough to cover my use without enough additional power
    Plus battery that can last 2 nights easily

    https://mybroadband.co.za/news/energ...-2022.html/amp
    Last edited by Veneficus; 2022/01/14 at 08:10 PM.
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  21. #34
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    Default Re: Going solar: starting to investigate.

    I can't believe how much Jo'burg residents pay for electricity plus the fixed costs!

    https://www.moneyweb.co.za/news/sout...iggest-metros/

    Africa changes you forever, like nowhere on earth. Once you have been there, you will never be the same." - Ernest Hemingway

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  23. #35
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    Default Re: Going solar: starting to investigate.

    Quote Originally Posted by Paul Dold View Post
    I can't believe how much Jo'burg residents pay for electricity plus the fixed costs!

    https://www.moneyweb.co.za/news/sout...iggest-metros/
    That is exactly why I want to go pre paid and then install solar
    To get away from the theft
    2007 Subaru Forester 2.5XT
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