SIZING EXERCISE: from grid to PV/solar in phases - Page 3




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  1. #41
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    "Get rid of the 3fase pump and get single phase."

    Easier said than done. 200m deep and another 200m from the DB. Using one live phase wire and the neutral isn't really acceptable?


    "Keep us posted on your quest to go DC with the pumps, I could not get a viable cost solution here."

    Yeah I doubt the cost is less than the savings.


    "Note that the single phase pumps might say .75kw but aside from the startup current (you need a contactor for the spike).
    I have 4 of these .75kw pumps for borehole, pressure, etc - they actually run at just under 1.2kw constantly and not .75kw, only my pool pump runs at around 700w"

    Yes, I'm aware that a 0.75kW 3ph pump isn't the same usage when 1ph.


    "Would not advise to go below 5Kva inverter for the water pumps. (I do run 3x 1.2kw pumps at the same time via my 5Kva)"

    Thanks, I won't run all at the same time if I'm on an inverter, probably either the borehole OR the pool, not both.
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  2. #42
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Sounds expensive. Well for my 2cw here is a company I found in JHB that custom makes this sort of kit for housing, offices and such. Got some LiFePO4 batteries from their warehouse once and its quite interesting what they are up to.

    https://www.freedomwon.co.za/lite-ba...heet-download/

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  4. #43
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by swakop_toe View Post

    Only P.E. allows/can facilitate feeding power back into the grid, so no, you cannot/may not.
    Not strictly true, Nelson Mandela Bay, Cape Town, too some extent eThekwini, and virtually all private third party energy suppliers (eg Voltano etc) allow feeding back energy.

    GridTie also allows you to fall back to EKSDOM should your batteries and genny fail.
    That's not the main reason for Grid-Tie. Grid-Tie allows the Solar inverter to deliver what it can, with the shortfall being made up by the grid. So you can have a 3kVA inverter and a 10 kVA load. In fact 99% of Grid-Tie inverters aren't evenb connected to batteries or generators.

    Consumption does not equate to Demand. This is where EKSDOM also fail. The peak demand times...
    Only valid if you are a provider that cant provide. For a consumer with demands that meet availability they are the same thing.

    You have to measure your DEMAND first Jakes. At least 3months, ideally, a full year.
    Yes and No - Unless you are expecting huge seasonal variances, even a week is good enough for this size system. Remember this is not a huge fully optimized IPP system. You only get to chose between a 3kVA or a 5kVA inverter, you cant spec a 3.78kVA inverter.

    What you can do in the meantime, even if you decide to not go solar, cost the following:
    Replace all cooling appliances with A+++ rated ones. AEG.
    Hob AND Oven -> Gas
    Add a Heat Exchanger to heat water, it will pump it through the geyser, so if the Heat Exchanger fails, you have the geyser as backup. Heat Exchanger if still grid tied - Thermal Solar if Off-Grid
    Add a Solar Water system to assist the Heat Exchanger.

    Replace AC pumps and compressors with DC one's.

    Do that cost exercise, calculate your savings, your ROI over the next, what, 15years, then do the reality check.

    Then resize the solar system based on the consumption and demand you measure with above systems in place.

    Each piece of kit that use more than 300Wh need to be recorded.
    Toaster, kettle, hairdryer, fridges, dryers, washing machine, all the air-cons, power tools, etc.
    As well as the rated Amperes....
    What are you going to do with the recordings. Practical reality check. If the aircon and washing machine are running, don't use the TIG Welder. Also don't blow dry your hair while making toast.


    You want to phase solar in?
    Split your DB by heavy load circuits and "low" load circuits.
    mmm, if only it was that simple, there is a whole hierarchy based on High-Low, Essential-NonEssential, Daytime-Nightime loads. All dependent on the system design. This is the most important part of a partial-phased system design.

    Solar on the low load first, but with the Efergy Power Monitor you will be able to measure each and every breakers load. YES

    So will be surprised what an old generation (10years) 42" LCD TV , amp and sub draws.
    YES, and throw that PLASMA away, its a Nuclear Power Plant absorber.

    Measure, measure, measure, first.
    Perhaps you will be pleasantly surprised that you are consuming less that anticipated = savings on the solar system.
    YES
    See blue above. This topic is a minefield if not tackled logically, one step at a time.
    Cheers

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  5. #44
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Fluffy View Post
    This topic is a minefield if not tackled logically, one step at a time.
    I'm trying.
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post
    i'm trying.
    very >:d;d
    Cheers

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  7. #46
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post


    "Would not advise to go below 5Kva inverter for the water pumps. (I do run 3x 1.2kw pumps at the same time via my 5Kva)"

    Thanks, I won't run all at the same time if I'm on an inverter, probably either the borehole OR the pool, not both.
    Now you're cooking. That's exactly how we solve these problems.

    Apply that thinking further and your initial 17.5kVA is now less than 10.
    Cheers

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  8. #47
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    I am in the same boat, but very luckily I only use about 700kWh per month. Gonna follow this thread in detail.

    Now for a quick hijack, but might be relevant.

    My 1200w, PWM type solar inverter just kapoet, so need to replace soon.
    I am wanting to replace this with a larger 5000w MPPT type inverter. It needs to be clever though, as I will also add panels when money allows. Currently have 5 x 100w panels.

    Say I have an AC load of 2000w and my solar can provide 400w at the time, the inverter needs to only draw 1600w from the grid. My current inverter is either solar or grid. It cannot use both sources simultaneously.
    Does the Inverters of today allow this yet, as starting small and growing the system will then be much simpler.

    My idea is not to go off-grid. I am happy to use grid at night. I want to safe running as much I can from solar during the day.

    Nerd
    Last edited by Nerd; 2018/10/09 at 06:54 PM.
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    @Nerd

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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Nerd View Post
    Say I have an AC load of 2000w and my solar can provide 400w at the time, the inverter needs to only draw 1600w from the grid. My current inverter is either solar or grid. It cannot use both sources simultaneously.
    Does the Inverters of today allow this yet, as starting small and growing the system will then be much simpler.

    My idea is not to go off-grid. I am happy to use grid at night. I want to safe running as much I can from solar during the day.

    Nerd
    This is the crux of the matter.

    To be able to be able to have a load of 2000W with 400W being supplied from the Solar and 1600W from the grid you need a Grid Tied inverter. (400 supplied from the solar and 1600 supplied from the grid)

    This is where so many people burn their fingers. Many many of the cheaper "hybrid" inverters (Like the Axperts etc) cant do this.

    I am super reluctant to suggest products by name, but the Infinisolar is basically a well priced Axpert with a Grid-Tie capability.
    Cheers

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  13. #50
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Fluffy View Post
    This is the crux of the matter.

    To be able to be able to have a load of 2000W with 400W being supplied from the Solar and 1600W from the grid you need a Grid Tied inverter. (400 supplied from the solar and 1600 supplied from the grid)

    This is where so many people burn their fingers. Many many of the cheaper "hybrid" inverters (Like the Axperts etc) cant do this.

    I am super reluctant to suggest products by name, but the Infinisolar is basically a well priced Axpert with a Grid-Tie capability.
    Thank you Fluffy.
    I will look into this, as this seems the most logical and viable solution to me. But yoh, that Googled cost
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Fluffy View Post
    Now you're cooking. That's exactly how we solve these problems.

    Apply that thinking further and your initial 17.5kVA is now less than 10.
    Put them on a shedding relay and they canít run at the same time. Before I did solar water heating and gas cooking I had my stove and geyser on one to reduce my main breaker size - which in PMB attracted a fixed charge based on size.
    Too often we enjoy the comfort of opinion without the discomfort of thought. JF Kennedy


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  16. #52
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Jelo as you are using a dishwasher when full - bear in mind that they consume more power when heating the water that a normal element geyser uses. To manage that the dishwasher does not get used when the geyser also comes on will impact the size of the system.

    I would agree with previous reply to go the heat pump route for geyser. May be you can find a position within 5m from the geyser. This has a much shorter payback than solar. We use hot water after sunset so had to go this route instead of solar geyser. Gas also a good option.

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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by ekkekan View Post
    Jelo as you are using a dishwasher when full - bear in mind that they consume more power when heating the water that a normal element geyser uses. To manage that the dishwasher does not get used when the geyser also comes on will impact the size of the system.
    An AAA rated dishwasher can't possibly use more kwh than a 100L geyser. Yes, the load might be 1.5kW but for 10 minutes, that is 250kwh.

    Most geysers sit and do zip most of the time. But yes, I will have to factor in the possible 3kW peak load if BOTH run at the same time. Ditto all the other high load appliances like microwaves, kettles, vacuum cleaners, etc.

    I have to over-spec: trying to micro manage concurrent devices would be silly.
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  18. #54
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Fluffy View Post
    This is the crux of the matter.

    To be able to be able to have a load of 2000W with 400W being supplied from the Solar and 1600W from the grid you need a Grid Tied inverter. (400 supplied from the solar and 1600 supplied from the grid)

    This is where so many people burn their fingers. Many many of the cheaper "hybrid" inverters (Like the Axperts etc) cant do this.

    I am super reluctant to suggest products by name, but the Infinisolar is basically a well priced Axpert with a Grid-Tie capability.
    I was also wondering about dual feeds and how to manage that..........
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post
    "Get rid of the 3fase pump and get single phase."

    Easier said than done. 200m deep and another 200m from the DB. Using one live phase wire and the neutral isn't really acceptable?
    Maybe speak to irrigation specialist that does pump installations, I was told 3phase is old school and not a biggie to convert to single - but better get an expert to assess your setup.
    Alternatively you can always put panels at the borehole location with a Solar pump if EWC is not an issue.

    I run single phase pump & my borehole is about 300meters from the inverter and the pipe does about 85m climb to my tanks (pumping uphill), but then the pump is not 200m below the crust like yours. (I'd love to have straight solar pump from panels, but panels will be gone the day after installation via EWC criminals..)
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by Kamakazi View Post
    Alternatively you can always put panels at the borehole location with a Solar pump if EWC is not an issue.
    Are you insane? Do you have any idea how fast unattended PV panels get redistributed? Especially when hidden in the bush 200m from the house? There is a reason why I only have plastic and wooden droppers. The only reason the borehole pump hasn't been stolen is because 200m of full pipe and a 20kg pump isn't easy to get out of the ground.
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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post
    Are you insane? Do you have any idea how fast unattended PV panels get redistributed? Especially when hidden in the bush 200m from the house? There is a reason why I only have plastic and wooden droppers. The only reason the borehole pump hasn't been stolen is because 200m of full pipe and a 20kg pump isn't easy to get out of the ground.
    Settle down, settle down, settle down. There is a reason us Capies stay down here... We still have it easy...

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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by kenskind View Post
    Settle down, settle down, settle down. There is a reason us Capies stay down here... We still have it easy...
    yes and its the reason most Vaalies want a Western Cape visa

    ek moes my neef se wynplaas in die Paardeberg gekoop het toe hy wou ophou boer en gaan visvang........

    toe koop die Badenhorsts die plek

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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post
    yes and its the reason most Vaalies want a Western Cape visa

    ek moes my neef se wynplaas in die Paardeberg gekoop het toe hy wou ophou boer en gaan visvang........

    toe koop die Badenhorsts die plek

    https://www.google.co.za/maps/place/...5!4d18.8186373
    ook maar lekker stupid jy moes ja.

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    Default Re: SIZING EXERCISE: from grid to PV/solar in phases

    Quote Originally Posted by jelo View Post
    An AAA rated dishwasher can't possibly use more kwh than a 100L geyser. Yes, the load might be 1.5kW but for 10 minutes, that is 250kwh.

    Most geysers sit and do zip most of the time. But yes, I will have to factor in the possible 3kW peak load if BOTH run at the same time. Ditto all the other high load appliances like microwaves, kettles, vacuum cleaners, etc.

    I have to over-spec: trying to micro manage concurrent devices would be silly.
    Thanks for the AAA info. Have not looked at current models and based my reply on older dish washers like what we have. So we learn all the time.

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