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Proposed Offgrid Solar

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  1. #1
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    Default Proposed Offgrid Solar

    Hi Folks

    Not after any specific info, Just thought I'd start a chat about my upcomming solar foray.

    We bought 100 acres and are about to build a shed and then a house.
    Power is aviailable at the neighbours property and is within 50 metres of my boundary.
    What's not so good for me is that they brought the power across their land ( private property )
    It's also only single phase and I have amassed a collection of 3 phase machinery ( doh, I knew it would come to bite me one day )

    Without going into full depth financials suffice to say that a full blown offgrid setup would be considerably cheaper.
    I've got one quote from one of the larger local mobs which is still cheaper than the grid option.

    So here is what I'm looking at so far.....
    - Somewhere between a 7 and 10 KW solar array.
    - a Honda EM65IS backup generator.
    - and a 125 Kva generator to run the workshop ( I actually calculated that a 50 Kva gennie would do it, but I found the 125 with 400hrs on the clock at half the $ of the 50 )
    Rekon that should do it ?

    From the recomendations and my somewhat uneducated research I think I will go for an SP-Pro inverter.
    The quote for 245W panels was a bit dear I thought and so were the batteries.

    So if anyone has some thoughts on those 2 items I'd like to hear them.

    I'm sure I have forgotten something, but that should get us started.

    I am actually looking forward to giving the finger to the power Co for good, even if I'll still have a diesel bill. ( that would be mostly for the workshop side of things though )

    Cheers for now

  2. #2
    Slow but rough Uncle Bob's Avatar
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    I've nothing really to add except it sounds like a good idea.

  3. #3
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    I suggest that batteries are the critical issues to look into
    (a) the life of those batteries
    (b) maintenance required in order to get their full useful life.
    (c) safe and secure housing of these batteries

  4. #4
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    What size and voltage battery?
    2V telecom batteries in series?
    What about a [48V?] Dunlite wind turbines or similar as part of the package

    Going by what I have seen of successful projects you will need a separate well insulated and ventilated battery storage area and soundproofed genny house
    "A big boy did it and ran away"

    Legal disclaimer denying responsibility to be inserted here.

  5. #5
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    Quote Originally Posted by Moondog55 View Post
    What size and voltage battery?
    2V telecom batteries in series?
    What about a [48V?] Dunlite wind turbines or similar as part of the package

    Going by what I have seen of successful projects you will need a separate well insulated and ventilated battery storage area and soundproofed genny house
    Thanks for the replies

    The quote I had recommended a 48V system using 2V batteries ( 1400 Amp hour ) but they were $1400 ea x 24 Not sure if that's standard price?
    Any guess as to prices for wind turbines?
    Could the battery and genie be in the same room?

    Cheers

  6. #6
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    There is an Australian standard for solar systems you should get one of these. As for the generator in the same room no you can't they have to be in separate rooms. I had a little bit to do with an off grid system on a remote comms site but while I am electrician I didn't install it as we had to have a registered installer who by the way was a boilermaker in previous life to sign all the paperwork.

    You need lots of signs and the battery room has to be built a certain way. The system we built had 3 x 1350Ah batteries and heaps of solar panels. We only just replaced the batteries after 10 years of hard work with one 1650Ah battery and as we have mains power that switches on of a night to keep the batteries topped up.

  7. #7
    Resigned SilentButDeadly's Avatar
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    Quote Originally Posted by Barterbuilt View Post
    The quote I had recommended a 48V system using 2V batteries ( 1400 Amp hour ) but they were $1400 ea x 24 Not sure if that's standard price?
    Strikes me as a bit pricey...RPC in Lismore does a 1500 plus amp hour 'pack' of 6 x 2V batteries for less than $6K BAE Secura - 1530Ah - 12V (6x2V) Gel Cells - Batteries

    I'd have a yarn to these guys as they are the Northern NSW specialists for this sort of thing and have been doing it for a l-o-n-g time. They even do wind and hydro turbines.
    Joined RF in 2006...Resigned in 2020.

  8. #8
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    You need:

    Solar panels
    Charge controller / regulator
    Batteries
    Inverter

    Panels - Make sure there is NO shade whatsoever on any series connected string of panels. If you shade one panel, even something minor like a toilet vent pipe or a TV antenna, then you'll seriously drop the output from the whole string.

    Regulator - an MPPT (Maximum Power Point Tracker) regulator will work better than a PWM (Pulse Width Modulation) one especially when you need it most - when the batteries are significantly discharged.

    Batteries - I have no real experience with flooded lead acid in solar use but quite a bit with AGM (Absorbed Glass Mat) and Gel. Of those two I'd go for Gel every time in a solar application - there's very little difference in cost and they last significantly longer so it makes sense. The other common option is LiFePO4 (Lithium Iron Phosphate) - they cost a lot more than lead acid but in theory should last longer.

    Operating voltage - 12V is for camping and small things like that. You want a 24, or better still 48, volt system not 12V.

    And you need an inverter to run your loads. Make sure it outputs a sine wave, not a square wave, if you want to avoid problems especially with motors and electronics. They'll work, but you'll have fewer issues with a decent sinewave inverter.

    As for that 125kVA generator, that must be a pretty serious workshop you've got if you're using that much power. Even many commercial workshops wouldn't need that much.

  9. #9
    Community Moderator phild01's Avatar
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    Could he mean 12.5kVA!

  10. #10
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    Quote Originally Posted by Smurf View Post

    Batteries - I have no real experience with flooded lead acid in solar use but quite a bit with AGM (Absorbed Glass Mat) and Gel. Of those two I'd go for Gel every time in a solar application - there's very little difference in cost and they last significantly longer so it makes sense.
    We replaced flooded Lead acid with flooded Lead acid as they were significantly cheaper. Life of all deep cycle type batteries depends on number of cycles and depth of discharge we expect we should get at least 10 yrs as the cycling won't be as deep as we have mains backup.

  11. #11
    4K Club Member ringtail's Avatar
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    I'm about to embark on a totally off grid build not out of anything other than necessity. There are zero services to my land. With the whole battery thing, I will use standard deep cycle automotive batteries, lead acid,agm or gel. Before becoming a chippy I was a motor mechanic and I still have a connection to a wholesale battery supplier through my old boss. I can buy seriously big deep cycle batteries cheap enough to not bother me too much. Since my cabin will be small and the power requirements will be led lighting, fridge and water pump, 12 v will do fine. A lot of people completely overlook the automotive industry as a source of household products. As Nearly all 4x4's are 12 v there are bucket loads of cheap premium quality 12 v gear that the house industry noes nothing of. One just has to look in the right place to get top quality gear considerably cheaper than traditional domestic household suppliers. And think outside the square a little bit.

  12. #12
    Community Moderator phild01's Avatar
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    Series connect to increase voltage and you won't have to spend so much on the wiring.

  13. #13
    4K Club Member ringtail's Avatar
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    Lots of options. If I go 24 or 48 v I limit what I can buy easily off the shelf. On the other hand there is less voltage drop. If I go for a remote mount set up there could be a decent run to the cabin too. Fun and games.

  14. #14
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    Quote Originally Posted by Smurf View Post
    You need:

    Solar panels
    Charge controller / regulator
    Batteries
    Inverter

    Panels - Make sure there is NO shade whatsoever on any series connected string of panels. If you shade one panel, even something minor like a toilet vent pipe or a TV antenna, then you'll seriously drop the output from the whole string.
    There shouldn't be shade once the sun goes past the mountain and there isn't much I can do about the mountain

    Regulator - an MPPT (Maximum Power Point Tracker) regulator will work better than a PWM (Pulse Width Modulation) one especially when you need it most - when the batteries are significantly discharged.

    Batteries - I have no real experience with flooded lead acid in solar use but quite a bit with AGM (Absorbed Glass Mat) and Gel. Of those two I'd go for Gel every time in a solar application - there's very little difference in cost and they last significantly longer so it makes sense. The other common option is LiFePO4 (Lithium Iron Phosphate) - they cost a lot more than lead acid but in theory should last longer.
    The AGM and Gel are the pick, but dearer. The flooded would require more maintenence but may last the ten or so years till the lines come through. Not sure yet

    Operating voltage - 12V is for camping and small things like that. You want a 24, or better still 48, volt system not 12V.
    More than likely go with 48V

    And you need an inverter to run your loads. Make sure it outputs a sine wave, not a square wave, if you want to avoid problems especially with motors and electronics. They'll work, but you'll have fewer issues with a decent sinewave inverter.

    As for that 125kVA generator, that must be a pretty serious workshop you've got if you're using that much power. Even many commercial workshops wouldn't need that much.
    I probably only needed 60 KVA but this one came up cheap with only 400 hours on it. Gives me some room to expand. And yep, reasonably serious workshop.
    There seems to be a huge difference in the quotes still, considering they are much the same components.
    I am getting closer to figuring it out though.

  15. #15
    house trasher jatt's Avatar
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    Even with 24 V there are still many options out there. Nearly all trucks I have had dealings with have been 24, so of course items have been made to cater.

    I built my own 24 to 12 V converter years ago in a workshop that was serviced by 24V , but these are readily available already, so probably wouldn't bother again.
    When I die, bury me in the hardware store

  16. #16
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    Default Offgrid Solar

    Hi,

    I'm new to the forum but have a fair bit of experience with offgrid solar. A couple of things I picked up reading through the op and following posts.

    With generator sizing try and size a generator so that it will be running at 70% or more of capacity. This will increase efficiency of the generator and also you will glaze the bores in the motor running on light loads causing the engine to start burning oil.

    Batteries are the life of the system and cost around half the price of the whole system. They are rated at different discharge rates so make sure you are comparing apples with apples. You do get what you pay for in most cases and products such as Sonnenschein, Hoppecke, BAE, Exide and a few others have a proven history in Australia.

    The battery must be sized correctly or premature battery failure will occur. This must be calculated on the electrical load of your new home before the rest of the system can be sized.

    The selectronic SP Pro is a great Australian made inverter and can be programmed to suit any installation. Check if your installer is a SP Pro accredited integrator for a 7 year warranty on the product.

    If you have any questions I will be more than happy to try and answer them for you.

    Cheers.
    Ben

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