Troubleshooting Lost Watts - Page 1
Forum section: electronics / general

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 27, 2019, 05:32:41 pm
content: I have 4-100 Watt panels in parallel hooked to a 40amp MPPT controller that is charging 4 golf cart batteries in a 12v system. During an independent test each panel was producing 90watts, but when all panels are tied together via a 4-to-1 parallel connector wattage does not exceed 201watts from the panels according to the charge controller when no load is applied to the system. However when a 200 watt load on the system the controller reports 283 watts.The 4-to-1 connector is connected to 50ft cables running to the controller.Is the charge controller bucking the excess energy being produced by the panels? The controller is indicating MPPT charge mode, not boost or float, so the batteries are not fully charged... Confused? Appreciate any suggestions.

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 27, 2019, 07:55:07 pm
content: It would be nice to help someone instead of the usual drivel in the renewables sectionMy first option would be your charge controller has a current limit lower than the output of your 4 panels, perhaps you could provide a link or spec for the controller ?Second is that your 4 panels are not matched (same make/type/age etc) or are not evenly illuminated (same direction/tilt/shade) either of these could cause some of the panels in a parallel array to partially shunt the others UNLESS your "parallel connector" incorporates diodes ?50ft is a long way at just 12V, you may also be suffering excessive voltage drop on those cables! especially if you are using cables designed for 10 Amps to carry 40 Amps ? This may be interfering with the controllers MPPT algorithm.Just a few things to think about

author: jmelson
author_rank: Super Contributor
timestamp: March 27, 2019, 08:04:12 pm
content: It seems like it might be a much better scheme to put the panels in series. I think there are a lot of problems when paralleling panels.Jon

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 27, 2019, 08:27:38 pm
content: Thanks for the replies. Here is a link to the CC:https://www.renogy.com/rover-li-40-amp-mppt-solar-charge-controller/All panels are matching.Yeah, I was thinking the voltage drop might be a result of the 50' panel wires, but the panel wattage increases significantly when I put a load on the system.I was thinking possibly I am using too small of a wire (16AWG) from the batter terminals to the CC, but again solar panels wattage increases to nearly 300 when the system is loaded. This wire is around 10' long.Panel Specs:SpecificationsMaximum Power 100W Solar Cell Type PolycrystallineOptimum Operating Voltage (Vmp) 18.2V Connection MC4Optimum Operating Current (Imp) 5.49A Quantity 1Maximum System Voltage 1000 V(IEC) Length 40.00Open-Circuit Voltage (Voc) 22.8V Width 27.00Short-Circuit Current (Isc) 5.95A Height 1.40

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 27, 2019, 09:09:38 pm
content: Quote from: OpenCircuit on March 27, 2019, 08:27:38 pm50 ft of wire times two with 4X5.95A is 48 watts.If the light on the panels is not all the same then that will impact the efficiency.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 27, 2019, 09:20:40 pm
content: The 50 panel cables are 10AWG:Feet per pound: 17.54Nominal outside diameter (in.): 0.230Conductor stranding: 19 / 0.0234Max. amps per conductor: 40 AMax. voltage: 600 VTemperature rating: -40°C to 90°CLight is uniform across the panels.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 27, 2019, 11:32:13 pm
content: Quote from: OpenCircuit on March 27, 2019, 09:20:40 pmI made a mistake (other than not using the #10 wire) on the calculationsAssume 4 x 5.49 amp sources on 50 feet of #10 cable50 ft * 2 * .9989 X 10^-3 ohms/foot * (4*5.49 A)^2=48 watts.

author: george80
author_rank: Regular Contributor
timestamp: March 28, 2019, 12:15:46 am
content: Quote from: ahbushnell on March 27, 2019, 11:32:13 pmThis is POWER loss not Voltage drop.As the panels are only 18V, you are running it through a length of wire and then into a controller and will want the best part of 15V to charge the batteries at full amps, I'd say you are loosing too much VOLTAGE not Wattage.The reason you get more amperage when the batteries are under load is because the battery voltage droops and the available voltage is high enough to then charge them properly. As the voltage of the batterys come up as they charge the amperage drops off although the charge controller should to that anyway once the battery reaches 80% charge.There will be a loss in the controller as well as the cable and as amperage is product of voltage, that's what I'd be looking at.By the look of it your controller will take up to 100V input and auto detect if the system is 12 or 24V.24V is a much better operating voltage for a DC system but you would need to buy another inverter. Well worth it in my opinion as you then halve all your wiring size and loads. in any case from the lacking specs it -APPEARS- you could parallel and series your panels for a much higher input to the controller and get better efficiency that way.I'd check though because a lot of controllers have a range of input and output but they are usually PWM. I'd clarify but going on the specs it looks like you can use up to 100V and it will charge a 12 or 24V battery bank.If the panel have the normal MC4 connectors all you need to do is get a couple of sets of those Y connectors to parallel and series the panels you have now and that would be it. I personally would not just straight series all the panels because you could risk over voltingThe controller in cold weather and due to cloud edge effect which I see a lot and pushes the output of my panels way high. Not enough margin for error there so I would suggest a series Parallel arrangement would be much better and avoid problems. You existing wiring should be fine then as well.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 28, 2019, 01:22:48 am
content: I will try 2 in series with the other 2 in parallel and see what I can harness that way. I believe I have enough connectors to make it happen.EDIT: The panels are 16.7v at 9am at 38 N Lat.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 28, 2019, 03:23:15 am
content: Quote from: george80 on March 28, 2019, 12:15:46 amThat's why the units are in watts. The voltage drop is 2.19 volts.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 28, 2019, 03:03:45 pm
content: I tied the panels all together in series for a total of around 80v and did see 363 watts during a 275watt load to the system. The batteries are now in boost mode complicating my comparison from yesterday. Charge mode was about the same as the four panels in parallel at around 200w. Considering 363w, I suppose this is the max I can expect given the resistance from the 50' cables, which I COULD almost cut in half and theoretically achieve 375ish. This controller doesn't seem to care; just put 550w to it any way you can and under 100v.EDIT: OK 417W...think I will leave them in series.Greatly appreciate the help.

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 28, 2019, 03:42:34 pm
content: How are you measuring it? The reason I am asking is that I have seen some units that have poor measurement accuracy and many times drift.I once saw a unit in which the shunt measuring resistor did not employ a Kelving sensing. While one can calibrate out the initial copper resistance, copper has a huge tempco, and as the current heats up the resistor and therefore the traces, one would see the values drifting. That is one example that I analyzed.Have you double checked the measurements with trusted instruments?

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 28, 2019, 07:27:25 pm
content: Quote from: OpenCircuit on March 28, 2019, 03:03:45 pmGreat your sorted, may I suggest if you don't have already a two pole lockable safety isolator on the panels capable of breaking at least 20A DC at >=250V. Bad things can happen like equipment fires and you want to be able to safely remove the source of energy and also ensure your own safety when working on your equipment. DC can be a nasty thing if not respected!

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 28, 2019, 08:44:05 pm
content: Schmitt: I checked current and voltage with a UT61E (decent low-end) meter that has shown to be within tolerances based on reviews. All of the panels matched in output with this meter. However, I primarily use the blue tooth app interface with the CC to check system status.42: Yes you may suggest and I certainly will check into the breaker as a safety mechanism. The very thought crossed my mind at 80v and 5.5a.The batteries made it to float charge and it appears the CC is simply bucking the panels as panel wattage went to around 50w during float then actually increased to low 400s with a 200-300 watt load applied. I try to keep these flooded batteries at a min of 12.3v, so I can see the value of a 24v system. Will certainly look into a 24v battery bank as the system grows.

author: jmelson
author_rank: Super Contributor
timestamp: March 28, 2019, 10:51:47 pm
content: Quote from: OpenCircuit on March 27, 2019, 08:27:38 pmHUH? These seem really odd rating points. You are supposed to get optimum output just before you reach dead short current? At dead short, the terminal voltage is zero. I can't imagine how much the voltage will increase from 5.95 A down to 5.49 A, but I can't IMAGINE how it would go up to 18.2 V! Something seems really fishy with these numbers! That's a delta-I of .46 A, so the internal resistance of the panel is 39.6 Ohms!?!If it really WAS that high, the optimum output would have to be at a lower current. Also, 22.8 V / 5.95 A gives 3.8 Ohms resistance, which is still pretty bad.Jon

author: george80
author_rank: Regular Contributor
timestamp: March 29, 2019, 05:58:38 am
content: 80V is not life threatening even with DC. If you do feel the need to put breakers on the panels, Just use a couple of Normal AC breakers. DC breakers are very expensive and no matter what any safety sissys might say, are just not needed in this application.I have been using AV breakers on my systems which are doing around 350+V@12A and not had any problems despite tens of switchings under load over the last 18 Months.The thing is you have to wire BOTH poles and have the switches joined so they both break at the same time. If you only Switch one side you will get arcing but by breaking both sides at the same time, the arc is no bigger or longer lasting than switching a heavy AC load. I have seen some setups where they use 4 pole switches and wire each side from the panels across 2 switches in series so there are 4 Break points but again this would be unnecessary over kill in this situation.80V is nothing to get carried away with and if this works at 350 and double the amps, it will work with your setup but again, you must switch both sides together.The other thing I have Experimented with is switching the same sort of High power DC with normal DPDT ( double pole, double throw) AC relays. These are like a Double switch. In the powered position one pair of terminals has the power running through and when energized the other side do.Because the gaps on the contacts are only a couple of MM apart at best, they are prone to arcing with DC. To switch DC I found the better thing was NOT to switch it but to divert the load. DC has like a Momentum and when you turn it off it's like the electrons want to keep going and they will jump the gap and the arc which is exactly like welding in miniature will fry the contacts and possibly cause the relay to catch fire.What I found was when using a relay ( Normal AC we are talking here) instead of switching the power off, divert it to a Dummy Load.This gives the electrons somewhere to go and they don't arc the contacts. I also found that you don't need a full load, around 50% of the current being switched in the dummy load was fine. It could go below that but that could get sketchy but 50% worked every time.Again, I wire both the pos and neg leads through the relay so they are both broken and switched at the same time.The other thing is you don't have to even divert the power, you can just dead short it especially if you have a low power rating like in your system. I do it with mine as well. The DPDT relays are 20A and the wiring is higher rated still so shorting it on the other side of the relay works fine. The thing that helps this is due to the nature of solar panels, when shorted they go off their curve and only produce a fraction of the rated power. It does not hurt the panels to be shorted either.I use the relays for some remote switching applications and they have help up fine.I have had a load of people carry on about safety crap and this won't work but the fact is I have tested it and it does both in theroy and practice.Another thing I found is with using solar DC with resistive loads. All my strings are around 350V. I have fund on a resistive load, the voltage does not matter at all. I have in testing run up over 700V and dropped that onto a 240V element with no problems at all.The Limiting factor to make this work is the LOAD rating must be higher than the power coming from the array(s).IE, 700V into a 240V element is fine as long as the element is say 1000W and the power coming from the panels is less than that, say 900W.When the load exceeds the available current, the voltage pulls down below the load rating and all works well although of course there is an efficiency loss but that's not always a problem and can be an advantage in some situations. If the current is above the rating of the load then the voltage will go high and give faster burn out although a lot of elements won't be worried till the over voltage passes 15%. They will handle a lot more but then the element life tends to be shortened which again is not always a big concern.To do any real testing for the charge rate on your battery bank you will have to let it discharge a decent amount, below 80% capacity by turning off the solar charger and then turn it back on preferably with a substantial load to boot. The charger will only output max current when it needs it, not when the batteries are near charged and the load is under the chargers capacity.When the pack is down and there is a good load, THEN you will see your max numbers.... which will be in summer at mid day if your panels are correctly aligned and Orientated.

author: f4eru
author_rank: Super Contributor
timestamp: March 29, 2019, 05:49:52 pm
content: QuoteThis points to perhaps your battery being close to a charged SOC, a high internal series resistance, or having a current limit in the charger.

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 29, 2019, 07:16:52 pm
content: Quote from: george80 on March 29, 2019, 05:58:38 amOK George so I am a safety sissy!! I have never heard anybody give such stupid advice on a public forum before and it is completely irresponsible, DC breakers may be expensive in your opinion but they are essential for fire safety even if not for personal safety. You may have been lucky so far, I hope your insurance assessor is kind when confronted with your burnt house and excuse for proper circuit breakers!Here is a picture of what I use, I think it cost me ~£7 on Ebay and is a sound investment that should not be skimped, in the UK at least it is illegal to fit inappropriately rated switchgear and if someone happened to be injured or serious property damage result you would probably be facing a custodial sentence.Normally I agree with much of what you say but in this case I do not.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 29, 2019, 09:34:53 pm
content: Quote from: fourtytwo42 on March 29, 2019, 07:16:52 pmGood response. I found one on Digikey for $22.

author: george80
author_rank: Regular Contributor
timestamp: March 30, 2019, 03:07:41 am
content: Quote from: fourtytwo42 on March 29, 2019, 07:16:52 pmYeah, should have known. The typical saftey zealot high and mighty reply that ignores FACT and just subscribes to the cotton wool mentality.The one giving stupid misinformation here is YOU!Clearly you don't even know about what you are so quick to jump on the high horse and put shit on others about.Look up the standards in the EU and most other parts of the world including Oz and most other western countries and see what 80V is classified as. Extra low voltage ( up to 120V in DC) that has low risk. I can't find the regulations for the UK and couldn't be fked looking for them as I'm sure they would be the same and even when I showed you they were considered low risk/danger, I'd get some typical reply like " Well I don't care, I don't think it's safe" or such idiotic excuses as so often trotted out by those who think what they think must be right regardless of regulations they just made a song and dance about.QuoteNo, not on an 80V system. According to your country's regulations and many others, 80V is low risk and is NOT essential for personal safety at all. You should know what you are talking about before slagging off at people for giving bad advise when you own comments are so flawed.QUALITY DC breakers ARE expensive here and in most parts, unlike the fleabay china crap that floods the market in the design you illustrated. There are decent DC switches out there but there are a lot that are dangerous junk and YOU should have noted that.QuoteAhh geez!Not the insurance assessor fear mongering and ignorance. The favorite fall back of the safety zealots.The FACT is, in this country at least and I suspect the rest of the western world ( with the exception of the US because they are safety/ insurance mad there) an insurance claim cannot be denied because of something unrelated.In other words, If I have a kitchen fire or a flood, they can't deny it because the solar system on my shed isn't using a DC switch and had nothing to do with the problem.Now I know that will send the saftey sissys into a flat spin of protest and denial and where you are -may- be different ( but probably not) so look it up and make sure you aren't spreading more FUD before a melt down over that. Here it is law.As for luck, yeah right!Just went through a very hot summer and I had the system cranking out more than it is rated to ( a feat in itself) and I had not one problem. I probably checked EVERYTHING 25+ times keeping an eye on temps, currents and everything else and the ONLY problem I had was during a bad storm one panel on the end of the string ripped it's fastenings right though the metal beam it was correctly attached to and flipped over. Of course homes round here lost roofs and sheds ended up 300M from where they were, but there was NO chance of fire or anything else with my setup because it is all done to well in excess of capacity even if it does not meet your personal proclivities and ignorance.And luck has nothing to do with it. The insult in comments like yours is in fact you presume a person to be as ignorant as you and those like you, would be. I didn't just install these AC breakers thinking they would be ok, I suspected they may not. Like everything else I do that uncovers bullshit fear mongering like yours, I TESTED the things with a lot more power than what I intended putting through them BEFORE I installed them. I destructively tested a couple to see what they would do. $4 ea, what do I care as long as I know what they will and won't do. I also read up on a lot of things that are related so I had a good idea of the things taking place in relation to what I was doing and then put my theory to the test.I posted what I did on another forum that has several electrical engineers and electronics experts on it and one guy also tested what I said and came back saying I was right. He was surprised but admitted he could not fault what I said no matter how hard he tried.I would certainly you or anyone else conducting your own tests and showing the results. If' I'm wrong then I'm happy to learn but don't go spreading bullshit with things you don't know but just think don't agree with the safety crap you have been brainwashed with.I only use the breakers as switches because I also learn that they won't work in an overload on DC. As such I have them 4x over rated which I don't think makes a lot of difference to the contacts but the trip current. In any case the AC side is equipped with lower rather breakers than the inverter manufacturer strangely suggests. Why they suggest breakers with a higher load rating that the inverter is capable of I do not know, but I put in lower ones so if there is any problems, they trip asap not allow the inverter to keep pushing current beyond it's rating however that may happen. Worst happens my system switches off. I can live well with that.Like so many other things I have found in so many other areas, the parroted High horse safety mantras parroted by the ignorant are flawed and are not applicable in the practice I am putting them to.I do NOT suggest anyone go do anything that goes against normal application unless they test it for themselves and find out the story. The number of things you read on the saftey obsessed internet that don't stack up are more in my experience than the ones that do.I also have a couple of over temp sensors installed so if anything does get too warm, the system again shuts down.Don't assume just because someone does not use the regulation equipment they are not being cautious or know what they are doing.I'd stack my setup against anything built to regulation in real world failure testing. Of course there is also the subtle fact this is on the shed which can burn to the ground and poses no danger to people or my home nor anyone elses.Here is a picture of what I use, I think it cost me ~£7 on Ebay and is a sound investment that should not be skimped, in the UK at least it is illegal to fit inappropriately rated switchgear and if someone happened to be injured or serious property damage result you would probably be facing a custodial sentence. BWHAHAHAHAHA!In the 2 min of research I did on your laws, I found enough to see what you have there IS illegal! Oh the irony!!Hope no one does get injured from what ever you are running because YOU will be facing the custodial sentence.Unreal!People are so quick to jump on others with BS safety sooking and make a big deal of rules and regs and then prove their ignorance in SHOWING that they are in breach themselves!You seriously couldn't make this up but it's certainly nothing new. And NO, I'mknot going to tell you what is wrong with it. I'll do you a favor and encourage you ( not that I think you will) to look up the laws you are so passionate about and see where you have gone wrong IF you were running an over 120V system but in any case shooting yourself in the foot in your comments and indignation here.IF the voltages you are running DO come under the regs, then you ARE in breach of them.... not that you even realised despite the grandstanding. One look at that Picture and I said to myself that's not right and looked up YOUR regs and sure enough!The fact you accuse me of stupid and irresponsible advise and then show that would be laughable if it were not so hypocritical and potentially dangerous itself.Again, proves to me that the people whom are the most dangerous of all are not the people who know they are not following rules and regs, but the ones that THINK they are!The thing that also makes me laugh is you are promoting the use of those cheap switches completely oblivious as to how many of those have CAUSED fires and the HUGE amount of known problems with them! You say in the same sentence they are a sound investment and should not be skimped on then you mention that it is in effect potentially some cheap arse Chinese switch from Fleebay. The one you have may be OK but many of those cheap shit switches are pitifully under rated and have all sorts of problems which if you did any home work, you would see are responsible for more problems and fires than any other component in a solar system. You are in every way better off NOT to have one of these cheap switches installed IF it is not approved as so many on the market are not.It would pay to clarify this so you are not giving the irresponsible information you accuse others of.These switches are NOT all the same and need to be looked at carefully to make sure they are decent and up to the task.QuoteI quite like people disagreeing with what I say -IF- their position is based on sound and intelligent facts or reasoning. I learn a lot that way. I still learnt something with you talking garbage but it reflects much more poorly on yourself than I.In this case you launch into calling my comments stupid and irresponsible when in fact they are anything but and every rebuttal you give is completely flawed, laughable and even illegal in what you are doing yourself when you take issue with what I suggested.You can call me or what I say anything you like. Just make sure you are not making a Hypocrite of yourself by talking crap and basing your position on flawed and incorrect assumptions rather than KNOWING what you are talking about.... especially when it can be factually shown what you said was wrong.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 30, 2019, 04:43:29 am
content: This is the CA electric code which is based on the US national electric code.https://archive.org/stream/gov.ca.bsc.title24.2010.part03/ca_2010_title24_03#page/n615/mode/2up/search/solar

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 30, 2019, 07:50:51 am
content: GeorgeYour quick research of requirements here in the UK apparently missed the micro-generation requirements that embodies all you need to know in one document to help installers, an example is herehttp://bpva.org.uk/media/38266/new-guide-to-installlation-of-pv-systems-mcs_20130530161524.pdfAs with all such documents the latest version is expensive but the older ones are free hence the 2012 date.Insofar as IMO is concerned they are not cheap Chinese rubbish or whatever, there website is herehttps://www.imopc.com/pages/productsI am sorry if I used intemperate language but you as a respected member of the community should be aware that not everybody here is experienced and it is better that they start and continue there renewable experiments within known safety guidelines that unfortunately you seem to presently consider a waste of time. They have usually been built up from years of practical experience by many people and I do not dismiss them lightly.

author: george80
author_rank: Regular Contributor
timestamp: March 30, 2019, 11:35:10 am
content: Quote from: fourtytwo42 on March 30, 2019, 07:50:51 amNot sure the point you are trying to make here and I'm not about to study all the regulatory requirements for another country but I did find the bit I was looking for in relation to the pic you showed of your setup and it confirmed it IS illegal and non conforming and that anything under 120V is considered " Low Risk".Perhaps you need to read through this yourself because what I picked up on was very basic and as I suspected, seems to be a universal no no because it is so basic.QuoteRead what I said again carefully.I did not say the switch YOU had was rubbish, I said many cheap ones on ebay were. I 110% stand by that statement.QuoteI couldn't give a rats about the language you use, I'm not a shrinking violet and can well take what I dish out.It's the grandstanding from a flawed position that shits me to tears along with the incessant safety drivel people feel compelled to constantly spew out these days as if everyone is a moron and needs protecting.When someone puts shit on what I have said and makes a song and dance about safety and then shows me what they have done which I instantly see does not conform to the safety standards they just broke my balls about, I get a might pissed off.QuoteYeah thanks.My outspoken and against the heard position probably makes me the most disliked person on any forum I frequent but fortunately I'm not interested in winning popularity contests or garnering the approval and social acceptance of the assembled masses.QuoteI am not sure I would say they are a waste of time, I think that is your spin and probably dramatization.My position is that not everything is black and white especially according to rules and regulations.I believe people should get out, get their hands dirty and LEARN from themselves. It's a whole different thing to hearing something and then to see it for yourself first hand and UNDERSTANDING what going on. When you understand something the knowledge you gain is far more wide reaching than the particular application you are looking at at that time. The next time you do something you can take some of what you have learnt and that experience to have a better idea of likely outcomes before you start.When you just read something, the knowledge is far less because knowing is different to understanding.As I said, I didn't just decide AC breakers were OK and I'd use them. I read all about why they weren't suitable. When I had that base knowledge which I never had before, I considered it and thought about a soloution. I went out and set up a test and TRIED to create a problem. When I couldn't because of my theory I knew it was safe but then put it to others to test too. When they did and agreed we all learned something and found a different approach.Same as what I said about using the DPDT relays. I didn't just dream up the 50% load diversion. I burned a few of the things up TESTING them to see what was safe and what was not. They cost 2 bux each and I got a heap from from a friend out of old machines he had waiting to be scrapped. I learned a long time ago not to believe 90% of what I was told but to go out and test it for myself.About 90% of the fear mongering I have read IS flawed but seems live VERY few people are prepared to try things for themselves and instead just believe and safety beatings they hear or read and don't even consider the logic or lack thereof behind it.If someone did what I said with the AC breakers or the relays, they would NOT have any problems at all.I implore you to do your own tests and find fault with what I said. Show me and everyone else here that i'm wrong. I'll apologise and piss off if you want me to but unless you can show there is something unsafe and could cause a fire as you suggested then you would do well to make sure your own house is in order ( which clearly it's not) before lambasting others.QuoteIronic you say you don't dismiss them lightly yet you illustrate you don't follow them either.That is either hypocrisy or ignorance but certainly undermines you apparent position either way. Least I am consistent!I look forward to seeing a Vid of you testing AC breakers and relays in the manner I described and learning why they are unsafe if used as I suggested.

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 30, 2019, 03:56:06 pm
content: Quote from: george80 on March 30, 2019, 11:35:10 amWhatever george! I am not given to reading long rambling posts nor prolonging arguments as I don't enjoy them for there own sake. However I would like to know in what way you think I am being hypocritical and not apparently following standards ?

author: george80
author_rank: Regular Contributor
timestamp: March 30, 2019, 04:53:21 pm
content: Quote from: fourtytwo42 on March 30, 2019, 03:56:06 pm* And then goes on asking questions to prolong argument that he supposedly does not enjoy*There's one example of being hypocritical.QuoteYou just answered your own question!Because you had a whine and a sook about the comments I made, carried on about safety and regulations and then posted a pic clearly showing you are not meeting the standards you carry on about yourself.When you going to do that test on the AC breakers to show how stupid and irresponsible my comments were?

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 31, 2019, 06:06:51 am
content: Quote from: george80 on March 30, 2019, 04:53:21 pmReally, and in what way in your world of pathetic insults does that picture infringe on anything ?

author: f4eru
author_rank: Super Contributor
timestamp: March 31, 2019, 10:17:33 am
content: Guys, dont play with electrical and fire safety.Solar panels are mostly dangerous.Breakers are not only necessary for electrical safety, but also for fire safety.An example how modern safety norms classify electrical and fire hasards:(in this case IT equipment norm EN62368)ES1 is not dangerous to touch (except when wet)ES2 is dangerous and needs one protectionES3 is dangerous and needs two protectionsNote that you can limit either current OR voltage:max limits for safe to touch in dry conditions :60V DC30V RMS AC <1kHz30 to 70V AC >1kHzCombination AC+DC have special rulesor2mA DC0,5mA ACp12:https://www.ofca.gov.hk/filemanager/ofca/en/content_751/SSAC_Paper_7_2018.pdfFire hasards have separate limits.

author: fourtytwo42
author_rank: Super Contributor
timestamp: March 31, 2019, 06:53:46 pm
content: And to the OP I am sorry for the spat on your thread, I hope you got the gist of whats appropriate, DC breakers for DC rightAnd they can be found for a reasonable cost, I got lucky a guy was unloading some excess stock, just check the spec before you buy.

author: Zero999
author_rank: Super Contributor
timestamp: April 01, 2019, 08:28:04 am
content: Quote from: f4eru on March 31, 2019, 10:17:33 amYes, it's power which causes heating and fire. P = VI. The voltage could be under 4V from a single cell lithium battery, but a short circuit could result in hundreds of amps, causing a large amount of power to be dissipated in a small area and a lot of heat, resulting in fire.

author: paulca
author_rank: Super Contributor
timestamp: April 02, 2019, 08:02:01 am
content: The thing to remember about some electrical equipment is "Will you be there when it does fail?". So working on stuff in the lab or stuff that's only on when you are there to hit the kill switch and/or the fire extinguisher you can play "I'm a big boy, it doesn't frighten me, I know what I'm doing", all you want.The stuff that you want to leave running while you are out of the house or in bed or that you will leave running while your children play in the house, needsfar,farmore respect.On topic. When taking readings from the MPPT charge controller, remember it will vary the power it takes from the panel by varying the voltage across the panel. As the battery nears fully charged with no load on it it will allow the panel voltage to rise out of the MPP and the current to fall to balance the charge current to the battery. With a fully charged battery and no load on my 50W panel the voltage will rise to open circuit voltage and the panel produce nearly zero power, even in direct sunlight (in reality it produces the battery float trickle power). I think the only way to really test the max power output is to saturate the load with a load that will pull more than the panels can theoretically achieve. At least enough for the battery to be providing some of the power. Even then it varies a lot due to insolation.Also, excuse me if I read wrong, but your charge controller support 12V and 24V systems and claims a maximum of 100V. I'm fairly sure this does NOT mean you can run 100V of panels into it. It simply means that when it raises the panel voltage to lower the power your 24V panels can produce at most 100V safely and not fry the charge controller. Some panels produce close to twice their optimal voltage when open circuit, so that would be 48V and stating an upper limit of 100V just sounds like engineering grace (doubling), not an excuse to run 100V of panel into it. 4x12V panels open circuit will hit as high as 80-100V leaving zero grace on that limit.