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Thread: Off grid 3 phase solar power
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19th October 2017, 08:35 AM #16
I would think that Dave would absolutely need batteries to have access to the amount of power he will need on occasion. No way will 10hp 3ph run straight off the panels/inverter.
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19th October 2017 08:35 AM # ADSGoogle Adsense Advertisement
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19th October 2017, 08:43 AM #17
Following all feed back and watching sime youtube about it too. By the time I get to it I hope to know a little more
DaveTTC
The Turning Cowboy
Turning Wood Into Art
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19th October 2017, 10:20 AM #18.
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Li ion battery prices are dropping quite rapidly and as of July 2017 the price was US$147 for a kW hr of cells
LIioncells.jpg
The price is being held high by speculators and the very high demand for batteries for electric vehicles.
Conservative predictions are for a price of US$100 /kWhr for cells before 2020.
This is without any significant breakthroughs in battery technology, or production or major changes in the Li Supply.
There are many Li mines only now just being opened up - it will be interesting to see what the cost of Li levels out to once these ones come on stream and mining and processing procedures are subject to more stable market pressures.
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19th October 2017, 10:43 AM #19
Bob, that is worthy of posting over in the other thread too:
Getting a better Energy deal - WHAT A JOKE!
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19th October 2017, 09:25 PM #20
As previously mentioned, Fronius do a range of 3 phase inverters, and Victron can interconnect 3 single phase inverters to provide 3 phase. Selectronics (Melb based company doing inverters etc for more than 20yrs) can also do this from their SP Pro range. The SP Pro has models that can operate at battery voltages up to 110 or 120V, and incorporate charge controllers and a range of other functions. Basically they can do anything anyone wanting to go solar might want to do, but systems need to be planned and installed and programmed by people who have a lot of experience and knowledge of the systems. They are not cheap, but have excellent versatility, expandability, and reliability. Utilising higher battery pack voltages reduces the currents involved and ultimately reduces cable costs and power losses.
Battery sizing would be a function of the availability requirements for the 10HP capability. The battery would be substantially larger if you need to utilise the 10HP capacity in all weathers, at any time of night or day, during overcast periods, or for extended periods. Similarly, you would need in the order of 15KW of solar panels to source the DC just from solar on sunny days, plus a fair bit more for battery charging, house loads etc.
Tesla batteries have the hype but are a bit of an unknown quantity in terms of lifespan etc as they are reasonably new to the market, and use thousands of small cells in series/parallel configuration to achieve their storage capacity, just as their electric cars do. Traditional logic is that the fewer cells placed in parallel the better, so a battery pack comprising high capacity cells in series only (to achieve required nominal pack voltage) is a better option than the Tesla arrangement of low capacity cells in series/parallel configurations.
Ideally, the most economical arrangement would probably be a medium sized single phase solar installation for the house and moderate load equipment in the shop, plus a 22KVA approx diesel generator to support the heavy loads from the bigger gear and act as a backup generator for the solar.I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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19th October 2017, 11:46 PM #21GOLD MEMBER
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A fairly good explanation of a Tesla domestic battery, the biggest issue is the limited maximum amps that can be delivered, it isn't much at all.
CHRIS
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19th October 2017, 11:51 PM #22GOLD MEMBER
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Dave, buy an old tractor with an big hydraulic pump on it and hook up a generator to the PTO. Put it up on blocks and you have an off grid power supply and power to run machines on a line shaft. An old hydraulic motor should not be too hard to find to drive the shaft.
CHRIS
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20th October 2017, 04:57 AM #23
I don't know.
5kW is almost 21 Amps at 240V -- this would happily run SWMBO's washer and dryer for 6-8 hours.
what I find disingenuous is "assumptions" about battery life and long term degrade of a battery. The best number I can find on line is that, with the appropriate electronics and environment, Li-ion is good for 2500 charging cycles. Other references suggest as few as 500 cycles. 2500 cycles would be about 8 years use.regards from Alberta, Canada
ian
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20th October 2017, 05:09 AM #24
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20th October 2017, 06:31 AM #25
I line shaft was something I was interested in doing. Just don't like the noise of it.
Fletty 'S ideas with a line shaft and hydraulic motors sound s interesting. Must have a bottle of port with him to further discuss.
DaveTTC
The Turning Cowboy
Turning Wood Into Art
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20th October 2017, 07:49 AM #26New Member
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Some real figures for you on batteries, not urban myth or internet nonsense. LG's Resu Lithium battery is arguably the most affordable Li battery in Australia at the moment.
Pricing is around $8000 for a 10Kw battery of which onky 8.5Kw is useable. To quote one source "The LG RESU 10 is an Energy Storage System with 10kWhr of lithium ion cells rated to 6000 cycles or more. The unit is capable of putting out 7kW of peak power or 5kW continuously. ... The battery has 8.5kWhr of usable capacity with a round trip efficiency of greater than 95%.".
Charging and management of Lithium batteries is not simple, specialised hardware is required to integrate Li batteries in to off grid systems.
Charge capacity of the LG Resu is I believe guaranteed 6500 cycles at 85% depth of discharge, 8.5 kwh isn't a lot of useable power but if the proper measures are in place an average household could run on that. You'll note that the Resu is only capable of supplying 5Kw continuously or 7Kw intermittently. The above graph is simply rubbish, not at all representative of current pricing of around $1000 per kwh.
Lead acid battery types are a different ball game, the usual recommended depth of discharge for lead acid is 20% of capacity so banks need to be oversized if they are to last. The number of charge discharge cycles available with Lead acid batteries is proportional to the depth of discharge, mininise the discharge and your bank will last many times longer than it would with total discharge cycles.
Decent solar lead acid batteries (AGM and Gel included in the definition of lead acid) can last up to 20 years.
Best practice with any with any off grid system is to maximise use during the hours when the sun is shining, keep everything as efficient as possible to minimise the draw on your battery.
I probably should mention, I'm a technician, I sold and installed small off grid systems in the 90's and currently use both on grid and off grid systems. If anyone is interested I can give you a run down on my off grid scenario, some costings, performance considerations and measures taken to make the system perform adequately and maximise service life..
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20th October 2017, 08:06 AM #27GOLD MEMBER
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That would be no where near enough for my house, it would be lucky to run the network and computers with everything going. What 99.9% of people think batteries will do is that they will act as a complete back up if the power goes down and that is not the case at all. Some years ago we had a bush fire go through our town and the power was off for days, during that time we had a big Honda generator hooked up and it would not start our fridge with everything else turned off. Admittedly it was running through a 50 metre extension cord but the start current for it must be very high.
CHRIS
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20th October 2017, 09:15 AM #28.
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The $100 mark is not just based on that curve but also on things like, new Li mines coming on stream (A projected oversupply of Li was even predicted 12 months ago) and the 15 new Megabattery facilities currently being built. It does not include technology break throughs although this s probably likely to result in different batteries.
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20th October 2017, 09:22 AM #29.
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That's because the way the battery is discharged and in a related way its temperature are significant in determining the number of recharge cycles. My old iPhone battery lasted for 6 years with an average recharge cycle of 2 days that makes it 1100 recharges. It's actually still working (I use it as an MP3 player) but the amount of charge it holds is now significantly less than
when it was new
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20th October 2017, 10:37 AM #30
Dave
Just returning to your initial post, why do you wish to go to solar and battery storage?
It seems to me that there are several of potential reasons why this might be:
1. A desire to be free of the grid and all the associated constraints. Independence if you prefer and possibly just on an altruistic level.
2. The belief that it will ultimately be a cost saving measure.
3. Unavailability of grid power at an economic rate.
Around our way we have the road going south towards Goondiwindi (pronounced "Gunderwindy" by the way and shortened to "Gundy," the same as the little town in the Upper Hunter on the way to the Barrington Tops) and for most of the people living in this area they have an electrical system off the grid. This is only because the cost of running power lines is so expensive. They have solar and batteries by default. No economic alternative. As others have already said, you may well need a larger system than appears to be the case theoretically on paper.
I believe at the moment an off the grid system is significantly more expensive and limited in what it can deliver. All those people on the Gundy road will have gas fired ovens for example and in addition solar hot water. They seriously limit what they will run on electricity. I think the running of large electric motors would challenge most systems or be very expensive to set up.
Sorry to be a kill joy.
Regards
PaulBushmiller;
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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