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Forum Index : Solar : Grid connected inverter off grid
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renewableMark Guru  Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Oh hell, looks like a project and a half. Oh well , tackle one bit at a time, just like leggo. Thanks guys, I'de be buggered without help  Cheers Caveman Mark Off grid eastern Melb |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Yes, it certainly can turn out like that. When I started my dual stack inverter I thought rewinding the toroid would be the hard part. Turned out to be the easier, if tedious, part of the project. If you are mad enough to design your own PCB & associated circuitry then there are possibly lots of pitfalls waiting to catch you making magic smoke. Good fun if you enjoy that kind of learning process. Been there, done that and am now the proud owner of the biggest & most elaborate home made inverter described here (just bragging a little  ). You can read all in the 40 odd pages of 'building an inverter from scratch' thread.Persistence does pay off in the end  Perhaps following Clockman's book is also a good way to start (I have not read it) and you can get the PCB's from him too. A tip: make sure if using your aerosharp heatsink that it will fit to that board. That heatsink is excellent, some builders have trimmed it down but in my case the full size easily handled 3KW continuous load for hours on a 35 degree in the shed day recently. Smaller heat sink means bigger fan & more running of it, perhaps OK if the noise is no problem. My inverter is really quiet at 3KW, a barely perceptible hum. Tested it to 6KW but my battery bank capacity will not let me do that for long. Fridge cycled on on top of that too. As mad mentioned, these double stack units will start and run anything single phase that can be found in the average home. Klaus |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
It is no problem to cut the heatsinks as required. A few months ago I acquired a 3 phase table saw with a planer etc, I added a Variable frequency drive so it runs off single phase from my inverter. It came with a proper Aluminium blade and does a really good job of cutting the Aerosharp heatsinks to size. You could not get them any better with a milling machine. A bit of WG40 and it cuts through them like butter and very little heat unlike the ones I did before with a dodgy circular saw and cheap table mount. Took ages to cut and had to stop and cool them down as they got too hot to handle. If you don't have the gear an Aluminum fabrication shop could cut them for you when you know the size required. I agree with Tinker, winding the toroid seemed daunting at first but once you get into it it's not so bad, just takes a bit of time. If you follow Clockmans book etc it is no harder then the kits you would have done before, just on bit bigger scale. At the end you have a serious inverter that will out perform most commercial ones. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
I got a 8kw 12v unit similar to the one in the link above ie blackjack (it was originally a replacement for a 2400w sine waver that blew up, the seller didnt have any more and offered me this as a replacement) Apart from its sheer size (it was used in my 4x4 for camping and work hence the 12v) its been a bloody beauty- Its even run a stick welder fixing a broken trailer drawbar offroading, and apart from flattening 3x120ahr bats in minutes, handled it beautifully, has run a house for over a week with a bodged battery bank (ie every car battery we could scrape up all cobbled together) after a cyclone up north a while back Apart from being 12v, I'd use mine in my house, but it will continue to serve in the ute instead and I'd go higher voltage for the house/workshop inverter |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Hey Madness, that link for the 80A charge controller wasn't set right it led me to an inverter, Which one did you mean? Thanks Boppa and Tinka, I think it's a wiser decision to take my time and set it up properly, looks like this will be a great performer. Cheers Mark Cheers Caveman Mark Off grid eastern Melb |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Sorry Mark, here it is 80A MPPT Charge controller these are a direct rip off of the Outback units. I have not seen one in the flesh but from research, I did before people are saying they are okay. These are 80 Amp regardless of voltage, they will work on 12, 24 or 48 volt but the amount of power they will handle is halved each time you halve the voltage. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Thanks again mate. Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
If the aurora can connect into the ozinverter can it use the mppt in that unit then? Actually, am I better off not knowing that for now and just get a reliable system up and running, with the ozinverter and a reliable stand alone solar charger before complicating things with other added integrated components? Common sense tells me yes. Cheers Caveman Mark Off grid eastern Melb |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Hi Mark, I am ironing the bugs out of a very simple and cheap charge controller ATM. This will control the power output of your GTI, it also allows the GTI to work at full boar when full MPPT optimised output is needed. In addition to this it will also control at least a 5KW PV array charging DC directly to your battery bank. With a slave board connected to it you could control another 10KW of panels. Cost will be around $100 to build both master and slave boards. You could substitute one of the low voltage DC coupled arrays for a second GTI. This charge controller does not have MPPT for the panels not connected via a GTI. It relies on using panels that have a maximum power voltage just over 30 volts, by connecting these in strings of 2 the panels can charge a 48V battery bank at a normal Absorb voltage of 59V for flooded lead acid batteries such as a forklift battery. It may not give quite as much power as a MPPT charge controller but the money saved on a expensive charge controller allows you to buy a lot more panels and get more power for the same cost. The panels connected via a GTI will take advantage it's MPPT and give you the maximum possible. However you would only be able to connect one 5KW GTI to a Inverter that you intend to build, a 6 KW Inverter is not going to be able to take 10KW from 2 big GTI's. The charge controller will also be programmable to control 2 solid state relays. I use this to turn on AC power to my hot water system when there is excess power available. You could use the second relay as I plan to control your AC to prevent discharging your batteries. There are many other possibilities to use power that would otherwise not be used. It is all controlled by an $5 Arduino microcontroller which we can program as we wish to do what we want. Here is a couple photo's I took yesterday of the charge controller working with a 5 KW Aurora GTI, there was only one 1.5KW array connect at the time. The copper bar on the left side is for connecting the DC to DC panels, the right side is controlling the power to the GTI from the panels.   There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Outstanding Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
I just re read this as I had a hard stressful day yesterday and was a tad pissed when I read it yesterday. After reading it now, holy crap, that really is very impressive! Well done. Having clever buggers like you around to help fella's like me is truly amazing and very appreciated. That would be an immense help to many, if you make that board available to the public. Cheers Caveman Mark Off grid eastern Melb |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Files to make the boards are posted here 8th post down. This is the version I am working on ATM, I will be making a number of changes to the next batch. All the information is there including the code for the Arduino for those that are keen. When I get it worked out better I will put up the end result. Just would like to clarify about clever people, Oztules is the really clever one, I am stumbling around trying to make his design work the way I want. That said though I am happy to help as others have helped me. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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Ralph2k6 Senior Member  Joined: 24/09/2017 Location: AustraliaPosts: 129 |
I second renewablemark's comment. Very inspiring work by some very skilled people here on this forum. And the sharing and supporting nature means anyone having a go can learn and benefit, affordable/offgrid is a reality.. Just gotta have the time, unless some want to make some OZinverters to order Loving seeing some automation madness, let system rules keep the smoke in and the batteries Happy Ralph |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
For me the software is the easy part, keeping the smoke in is a little more challenging. I have had this concept working now for quite a few months, it regulates the battery very well. For some reason the new design has thrown up some challenges, I think I have sorted it out but need to test it a little longer to be sure. If building an inverter is a challenge the next best option would be to buy a low frequency powerjack, just half the output figures they give you and don't touch the HF (high frequency) ones. For someone to build these to sell and be viable you would have to pay at least $2,000 when you consider how much labour is involved. Then there are all the regulatory considerations. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Ralph2k6 Senior Member Joined: 24/09/2017 Location: AustraliaPosts: 129 |
Agreed madness, the price would have to be at least 2k region. Regulations would not help us as 'off grid' homebrew hobbyists. What I mean is that we're not talking about retailing the units, just paying for time/materials for 'component assemblies' between peers. Would not call the unit a 'turnkey setup' due to the implications some people might raise..(regs) I'm trying to score some 2nd hand ups units to modify but there are some who have more $$ and refurb them for sale it seems. I'm quite time poor due to family requirements but its been very exciting and frustrating seeing the progress that I've not been able to have a go at myself. That's why its so good to see such a supportive group here helping each other out showing ideas and fault finding theories/circuits. My hats off to you guys.  And thanks Glenn for running this forum. Ralph |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 438 |
Being new to all this solar/inverter stuff, I thought that the HF inverter versions are lighter, needs smaller gauge wires, and easier to build. I don't know the pros and cons of LF and HF. If the load is completely off grid, do I have to worry about regulations? Please enlighten, thanks. |
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| Ralph2k6 Senior Member Joined: 24/09/2017 Location: AustraliaPosts: 129 |
Have a browse through the forums tinyt. I have looked at HF units mainly by Voltronix. Generally they don't handle surging loads. One user even had their vacuum cleaner take out their HF inverter! LF are heavier and maybe a little less efficient but its a worthwhile trade off. Rules and regulations are important to follow to a degree. Insurance and safety are the important things to consider there. Ralph |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
LF Inverters are far more robust and can start things like induction motors that that HF ones can't without loosing their smoke. Yes LF inverters are a lot heavier and cost more to manufacture, which would you prefer, an inverter that craps itself when you want it to do some serious work, or one that will do it without the slightest bit of fuss? What I meant by the Regulatory issues is that if I built an inverter and sold it to you and someone at your home got electrocuted I could end up in court and losing everything I own. That is the context that I was talking about not you buying an inverter from ebay and installing it yourself. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 438 |
Thanks Ralph and Madness. I have looked at some UPS designs which mostly have HF Inverter sections. I assume they have some load current sensors. Won't the sensor limit load current surge? So in case of a table saw or vacuum cleaner load, they will do a soft start instead of jerk their rotors from standstill? I have not done any testing, based on what I have read so far in this forum, can I conclude the HF Inverters are limited to their specified loads and type while LF Inverters can take on almost anything like stick welders, banks of incandescent lamps, etc. Just trying to understand. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Lots of top blokes on here helping clowns like me Till I get the LF OZinverter built, would it be possible to use this instead of wiring that other soft start into the AC? BTW I just finished fitting 3kw on the roof! Jeez, harder than it looks.  Having a nice cold beer now. Cheers Caveman Mark Off grid eastern Melb |
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