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Forum Index : Solar : Solar experiment
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| George65 Guru  Joined: 18/09/2017 Location: AustraliaPosts: 308 |
I would have said that 10 years ago too but really, it's no big deal. You just have to keep your wits about you and make sure you turn everything off before you touch anything. I play with 500V+ all the time with my solar system and it's no Biggie. I just make sure there are 2 Points of " breakage" in any circuit I'm working on, Usually a switch and a disconnected connector and it's safe as houses. My biggest problem has been wondering why something didn't work when I went to turn it on and then remembering I only put back one of the breaks. Getting more used to that now and although I'm the laziest SOB around, I don't shortcut getting off my fat wide arse and going and doing the 2nd break. You also just have to make sure that unlike 12V or something, all wires are insulated in connector blocks and junction boxes when you turn anything back on or you turn it on, take your measurements and turn it off then enclose it properly. I don't know if you are the sort of person whom might wire something up in 240 mains power but if that does not worry you, no other mains or high voltage DC should either. The smart practices are the same and you'll be just as dead if you stuff up on one as the other. I am a certified nut job so I don't care that much if I live or die ( as long as I'm not sick) so I get a bit of a thrill and a lot of fascination out of holding a couple of wires attached to 500V of DC from my panels and pulling long arcs with it. I had bad depression years go and would play with live wires doing 1000V Cm's away from bare skin and kind of figured it was my " Meant to be here or not" test. Seems I passed so while not reckless or deliberately stupid, I'm not nearly as scared of things as I used to be. I couldn't tell you how many times in life I have done all sorts of dangerous stuff I pretty much expected to get bitten by because I KNEW I was doing something stupid and dangerous but did it anyway. I have NEVER been hurt by any of my conscious wrong doings yet. Mind you, I don't ride pushbikes off house roofs or any of the other endless " Well WTF did you expect" things like I see on YT vids, but I have driven fast cars too fast, done lots with machinery that should not be done, played endlessly with BIG fire and other such things. Likewise I can tell you MORE times than I have done stupid things, I HAVE been bitten doing totally innocent things people would never think twice about and do every day. It's as if I took a bath every day with a mains powered radio perched on the side of the tub without a problem but then got out and tripped on the bathmat and split my skull open on the basin. It drives me mad! The things that should bite me to teach me not to be stupid Never have but the thing that nothing is wrong with catch me out. I put it all down to simply being aware you are doing something you shouldn't and being on your guard BECAUSE of that. Not a lot of that self protection instinct kicking in while you are putting a t shirt on.  Anyway, you have to make your own decision. If the fear takes away the fun then the answer should be obvious. If you can't trust yourself to keep your mind on the job, also obvious. If it's just that the amount of volts sound scary and you'd play with 240 happily, then really it's no different. If you screw up with 12V and don't thoroughly understand what you are doing, the behavior and risks of what you are playing with, then don't do it either. I will NEVER tout " safety" crap because I can't stand the whining safety sissys but I DO believe in common sense and understanding what you are doing, the risks and the reality rather than fear mongering. Be careful and think what you are doing BEFORE you do it and its the same. |
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| Dazza123 Newbie  Joined: 03/11/2017 Location: AustraliaPosts: 34 |
Hi George have you ever been bitten by hi voltage DC, I have and I prefer mains any day of the week. I got it from 800v DC on the anode of valve TX finals, I turned it off and didnt wait for the bleed resistors to do their job, every muscle in my arm hurt for two weeks and not something I wish to do again. |
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| George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308 |
Yeah, I bit myself about 12 months ago with 350V out of the panels picking up the wrong wires I thought were AC I had double checked were unplugged. :0( First lesson in being careful and not taking panels for granted. I was surprised it didn't hurt a lot more than it did which I didn't think was that bad, much like getting hit with the high voltage from an electronic car coil but it was admittedly not at 800V. If you are scared of making another mistake and getting zapped again, the only sensible thing is not touch it at all and get someone competent to do the work for you. The fear and nervousness alone is likely to take your mind off the job and lead exactly to what you do not want to happen. In that case, I agree, the DIY option is probably not for you and getting a professionally installed system would be a better option. Even if it is a lot more paperwork and expense, at least it is safe and you won't have to worry. There is a lot to be said for that and would no doubt make it well worth while for you. You might want to check install prices though. Last time I looked the difference between a 3 and a 5Kw system was not that much. Probably depend on your usage patterns and what FIT rate you can get. I'm aiming to get a 10Kw system myself to keep peak demand down even if I do have to turn it off in spring and autumn for a bit. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
There is an old saying. There are old electricians, and then there are bold electricians... Cheers, Tony. |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
 Are you talking about the crispy ones? DCHV + stupidity would be like a giant bug zapper.There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
A while ago I was relocating my batteries and charge controllers, I was moving the wires around sundown and somehow got a kick from it. The boot itself was not so bad but it made my arm pull back very violently and my elbow hit a steel support for the panels. That injury was very painful for over a month, that was from about 120VDC. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308 |
I'm already old in mental and physical state if not what some would call in years, i'm not an electrician and I am bold/ stupid/ unsafe/ wreckless/ whatever the purists would say because I don't do everything by the safety sissy handbook. Not sure what that adds up to? Does it mean i'm living on borrowed time or I'll be one of these bastards that does everything wrong and lives forever? Specialist yesterday that cost me $400 for a 30 min consult said I need to get my diabetes better or I'm going to take 5 years off my life. I didn't know they could calculate when you are going to die. Didn't have the heart to tell him I really didn't care anyway. :0) I should have asked him the date so I could make arrangements in advance and know when I could afford to really go nuts. Maybe catch up with a few people that have burned me over the years. |
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| Dazza123 Newbie Joined: 03/11/2017 Location: AustraliaPosts: 34 |
the mains hits I have copped, one was a hidden cable I drilled through and ended up across the room, the second was from a washing machine I was working on and I grabbed a live wire believing I had turned the switch of. I like RCD's these days, I believe they are a life saver and a must have Neither of them hurt as much as the DC. My belief is that with AC the muscles relax as the ac swings through zero where as the DC just contracts one way causing more damage. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
That is correct, and it does exactly that to your heart. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308 |
Given the multiple incidences you have had with being zapped, I can well understand your fear of working on things electrical. I have never been hit by anything AC and don't want to. Maybe I am more anal and careful than what I realise? As electrical work is a dangerous practice for you, I think it's really clear that it's in your best interests to hire someone competent and qualified to do what you need. As well as doin the work unscathed there is also the aspect of living and continuing to live with it. Needs to be done so no one is at risk and one needs to keep their mind focused on that side of things as well. Your next electrical mishap could be your last so you would be very wise to get someone in to do the work for your loved ones sake as well as your own. It will be money very well invested. |
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| Dazza123 Newbie Joined: 03/11/2017 Location: AustraliaPosts: 34 |
Still looking and thinking and came across this page that has the same thinking as Warpspeed but with a battery, I guess the battery in this setup is to provide some back up power. How its OK to link to this, i found it quite interesting as it provides some good reasons for doing this. http://reneweconomy.com.au/network-limits-on-solar-storage-could-accelerate-death-spiral-65424/ A question for the people that have been there and done it already I was looking at only Pure sine wave inverters but seen a number of references to modified being acceptable. I have looked at a couple of my cheap modified 12v inverters on a CRO and its not pretty. The Pure sinewave looks perfect. I have also purchased a Inverter generator in preparation of this seasons power shortages, only a smallish one to run lighting and entertainment and I have a old school Honda to run the Evap if needed. Just a bit of trivia |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
These low cost Chinese pure sine wave PWM driver boards are definitely now the best way to go. If you can grab two dead grid tie inverters, rip the original circuit board out of one and replace it with a Chinese PWM driver board. It obviously will no longer be a grid tie inverter, but just an ordinary dc in, ac out inverter. Use the large toroidal transformer out of the second grid tie inverter with a rectifier to produce dc from the grid. As an example of this, I will use a 1.5Kw Inspire grid tie inverter as an example, because its something I am personally familiar with. The Inspire toroid has two windings, one is 135v the other 230v rated at 1.6Kw continuous. The inverter will need to produce 135v rms to drive the primary, which must come from a dc supply of not less than (135v x 1.414) = 191 volts dc minimum. Probably 200v dc might be more realistic at full flat out power. We use the other large toroid to supply 135v from the grid. That drives a rectifier and a large capacitor bank to generate about 190v dc, which will probably be more like 170v to 180v dc under load. At night we are not going to reach 230v coming out of our inverter, probably more like 205v rms. But as we probably do not need a lot of power at night, that should run all the things that normally run at night off the grid via the rectifier. I have been running at about 205v rms at night for a couple of years. Everything works fine at that voltage. But I am about to fix that. During the day the solar panels should keep the dc voltage high enough to run your larger loads at the full 230v, and be completely free of the grid, except on really bad solar days. It will require sufficient solar panels in series so that the peak power voltage is 200v or slightly above. but its not really critical. Something like seven or eight 24v series connected panels in each group should be about right. That is all you need and will give you the most bang for your buck. It will cut your winter grid consumption by half, and summer consumption by eighty percent if you have enough panels to carry the whole daylight load, except on really bad days. If the voltage drop off at night is a concern, its not too difficult to boost the 135 volts feeding the rectifier, either by adding some extra turns to the large toroid, or connecting up a smaller transformer in series to add an extra 12v or 24v to the toroids 135v. No battery is needed, but a big stack of electrolytic capacitors will be required to both filter the pulsing rectifier output, and provide a stable dc voltage against the heavily pulsing dc current drawn by the inverter. Cheers, Tony. |
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| Dazza123 Newbie Joined: 03/11/2017 Location: AustraliaPosts: 34 |
Thanks again Warpspeed, you keep directing me in this direction and it makes great sense to go this way. I se a couple of threads in the electronics forum about these PWM units, can you direct me to the most up to date boards being used, I believe I read that a different one is now being used and then got confused. What size Capacitors are you using and where to look for them? a little confused as to why the output voltage drops at night, does the PWM control board not regulate the output to a stable Voltage? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Try the EGS002 boards from e-bay, and Google EGS002 for plenty of applications information and circuit diagrams. https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.XEGS002.TRS0&_nkw=EGS002&_sacat= 0 The output voltage drops at night because the dc voltage to the inverter (from the rectifier) is insufficient for the inverter output to reach full output. If there is 230v on the grid, and you drop that down with one transformer, then rectify it into dc, convert it back into ac with an inverter, and boost it back up with another IDENTICAL ratio transformer, there are going to be voltage drops throughout the whole process. You are not going to be able get 100% efficiency where 230v in gives 230v out. Its easily fixed though, by changing the ratio of one of the two transformers. But if you just use two identical transformers, there is going to be an overall voltage drop where the rectifier feeds the inverter. As far as the electrolytics go, the bigger the better. Get it working first and see how it goes. Its easy enough to add extra capacitors to it later if necessary. Cheers, Tony. |
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| Dazza123 Newbie Joined: 03/11/2017 Location: AustraliaPosts: 34 |
EG5002 is ordered is this LCD display ok for this or is there a better option? OK https://www.ebay.com.au/itm/0-91-128x32-I2C-IIC-Serial-Blue-OLED-LCD-LED-Display-Module-12832-SSD1306/182371257748?hash= item2a762c8d94:g:eZwAAOSwtYxZga5v I found a manual online but it doesnt say what current the +5v and +12v lines need to be? will they run straight from lm7805 and lm7812 regulators? presume this needs to be powered from a separate source. if feeding this in to a repurposed GTI mosfets is there any extra drive boards needed? I think at a minimum a board to make connects to and a suitable header so the driver can be swapped easily if it fails is a minimum? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
It will work fine without the LCD. That can be added later once its all going. Current is absolutely minimal, a 7805 and 7812 will work fine. No extra drive board is needed, but... If the mosfets do blow for some reason it will probably take out the gate driver chips on the EGS002 board. The EGS002 board is so cheap that may not matter. Alternatively you (could) fit external non inverting gate drivers in IC sockets for each mosfet close to each mosfet. If the mosfets blow, then just plug in whatever drivers were also taken out, and the EGS002 remains undamaged. Its a bit more effort to add the extra drivers, but its entirely your choice. Cheers, Tony. |
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| Dazza123 Newbie Joined: 03/11/2017 Location: AustraliaPosts: 34 |
ok half a step closer, Thanks looking at a header strip to hold the egs502 the best I could find was these 20 pin critters, are they suitable. next is using vero board good enough or what is the best way? https://www.ebay.com.au/itm/20x-Single-Row-Female-Pitch-Header-Socket-Connector-PCB-2-20-Pin-Strip-2-54mm-GT/16263322564 9?hash=item25ddb215b1:m:m8fwIguHi9k1_Gck8PyHOfA |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
If you are wanting a high voltage DC to AC inverter this kit using the EGS002 board might be worth having a look at. I have not had anything to do with these but it might be an easier way for you to achieve what you are trying to do.  There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| hotwater Senior Member  Joined: 29/08/2017 Location: United StatesPosts: 120 |
I bought a couple of these boards (not the one pictured)to ease building. Check pictures carefully. The board I got had a lot of surface mount components making it hard to work with. |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 438 |
First post, just getting my feet wet, please be gentle. Does that 2000W inverter kit need heatsinks and 380VDC and maybe other components? |
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