Modina

@JamesF. You can forget about net-zero grid usage when government or even the municipality is involved. Institutions will legislate and send you all sorts of levy charges. It's not gona be worth your while. The world over, the small people need to shun fake governments, puppets on WEF strings, and cut as many links as possible with BIG-everything. In a small, well run community, net-zero would be possible. You could, for instance, formalize an agreement with a neighbour that, for various reasons, does not want a solar system. You provide a bi-directional meter that both parties can monitor. During LS you agree to supply your neighbour with some power. In return, you use your neighbours Eskom supply to top-up your power in bad-weather conditions. The meter monitors the energy flow and you agree on some form of out-of-balance consumption payment, ideally outside the formal money system. With more complex/expensive inverter tech, one can install a system to optimize own-power generation WITH the neighbour's load. Cutting your strings with Eskom/municipality power might be risky if your agreement is with one single neighbour. He might move, die, get into a disagreement with you, etc. If a bunch of solar users and a bunch of only-grid users come together, you cover your base. Depending how isolated or not you stay, this might not be an option for you. However, modern living has trended for smaller and smaller units. Often, in these Bang-Jan-Gated-Communities you are so close, you can literally wish your neighbour happy birthday through your bedroom window. LOL. 3 or 4 neighbours that don't have solar could even network. Have an agreement that during LS, ONE neighbour runs a decent sized generator, sharing the power. Next day, the next neighbour feeds the system from his generator. You cut out noise and optimise consumption. You increase the life-expectancy of your own generator. You have system redundancy and a failure of your own generator is then not a train smash. There are many ways to skin a cat. We don't talk to our neighbours anymore. We need to re-learn ways of living of the past. Self reliance with support of your local community. This should be done for EVERYTHING. Food, services, medical help, etc. The days of relying on BIG-everything is over. I cannot wait to see the collapse of big Pharma, the Googles, Facebooks, Apples, Amazons, Microsofts, etc. of this world. What has happened the last 3 years is beyond words. Too many sheeple. This world will split. Guaranteed.

I am house renovating and last year I simply wasn't ready with a proper place to mount a system. Then in January, with the storm of load-sh!tting events, I went into overdrive getting an education and attempted shopping spree. I spend 2 weeks nearly solid, trying to source equipment. I'm a electronic engineer, so I understand tech, but I was new to this market and had to pick up the ropes. THREE times I placed orders with different suppliers and each order failed. Normally the final purchase price was still pending due to some sort of variable delivery charge, so the order needed to be accepted (by the supplier) and a formal invoice to be sent. I am still waiting for answers from some of these. Luckily I never made any payments. My initial gut told me to go for a 3KVA 24V system. Every time an order failed, I revisited sites and pricing and reconsidered my options. A friend said I should rather go for a 48V system. So at one stage I wanted to place an order for a Kodak 5.48 with ONE Pylontech at Powerforum shop. I was told the supplier is not willing to sell one battery. I would at least need to submit a power budget. Time was ticking. No example of a power budget was provided. Communications where slow, taking 2 days turn-a-round. I moved on and scrapped my 48V idea. I ended up ordering a clone on Takealot. A MCE 2.5KW VM II with a 3KW 60-400V MPPT. I paid R 6200. A very good price considering the high voltage MPPT. I then decided on a Hubble AM4 battery. It is rated at 110Ah with a max discharge of 100A. Rated at 1C. Well, at 1C and 110Ah it should actually have a max discharge current of 110A, should it not? But let's not split hairs. I order the battery from Liteglo, paid 20K. I should add that the MCE inverter's status on Takealot altered between sold-out and available multiple times over a period of about 2+ weeks(!) I intend getting panels later. Yes, I am concerned of a possible total meltdown of Eskom. Then I would sit with my finger you-know-where. Funds are not the problem, but again, my renovation is lagging and I am not really ready for roof dances. More importantly, I simply do not have the energy to go through another similar purchasing exercise, hitting my head against closed doors. So I want to take a breather for 3 months and wait for stocks to replenish before I venture into this market again. I do have a 5KVA gennie to fall back on, in a worst case scenario. However, the inverter self-consumption (inefficiency) is a problem. Thus I am a big fan of running as much as possible from 12VDC. Today, it is NOT about what you WANT but what you can get. That is my experience. I could not even get a fuse holder(!) I looked EVERYWHERE, including Auto electricians. Later I did manage to order one from Communica. You need to see what is in STOCK and realise, that even if you phone to confirm, next day the stock might be zero. I would recommend suppliers that are not dedicated solar system sellers as I think they are more likely to have stock. I think a solar seller is everyone's obvious first stop. Also watch out for scheisters out to scam you, as I expect more and more of them will be crawling out of the woodwork in these times. I see on Gumtree there are some guys asking an absolute fortune for total junk. When deciding on batteries, make sure that they can handle your required discharge rate, for whatever max power that might be required. For a 2.5KW inverter you want at least 100A. And then we haven't even factored in the 10% inverter losses. Those Mecer Second Life 200A batteries that @Red Falconmentioned, I think, are 0.5C or 100A peak. If those can be sourced for a good price, do consider them. Just know that they will not give the full rating of your RCT, Kodak 3.24 or whatever 3KW inverter you decide on.

@Gary Smith Mercedes drivers will always look down on Hyundai / VW drivers.... At R 3250 I presume you refer to the Takealot price. Note that their price went up, now R 3700. Judging by the pictures, this is an older model. The one @ABDurbs shows in his picture seems to be the current model. The new model is advertised for R3900 (Takealot). I have no idea what the difference between these models is. From Takealot comments, it seems that the older model might not have a communication port. I have no personal experience of these, but saw that Fivestar makes many models right up to 8.5 and even 10KVA units. If someone builds motorbikes, then I would trust them to be able to build a scooter as well. My recommendation for anyone that is not a Mercedes driver, would be to try and run their inverters at a nominal power of 50% of rating. @ABDurbs has the right idea. In other words, don't buy this 1KW inverter and hook it up to your microwave to see what it can do. Chances are, it will run the microwave, but you might have a pre-mature death within a few weeks or months. I would take my chance with a Fivestar Axpert clone before I would spend similar money on these Mecer 720W/1200VA inverters. Main reason is that the Fivestar is a proper Sinewave inverter and the (non-Axpert) Mecer is not. The Fivestar also has the PWM solar charger, if ever you would want to connect panels. I am very negative about future battery prices. Lithium is in short supply. However, inverters I would expect to come down in price. Why? E-cars. Even the smallest of vehicles has a 60KW power-plant and most are at least 120KW. The mass adoption should drive power electronics down. I also think the inverter tech will move substantially over the next few years. Industry has a habit to bring out advancements that makes the old obsolete. For most of us, Eskom has forced our hand into this tech and we need to go through a learning-curve. I think it is foolish to get your driver-license with a shiny new Merc. Yes, a cheap Axpert inverter might pack up. You will likely have paid LESS for it than the repair costs for guys with a Merc, in the event of them having a breakdown. The SA market for solar systems is currently terrible. The shortage causes everyone that has stock to inflate prices. In a certain sense, all Axpert inverters are clones. Is it worth to pay double for a Kodak or RCT? I think if you are a fine-tuner, and want to pull daily stats, etc. then the cheap clones might disappoint due to (likely) software/firmware limitations. The better names might have a bit more meaty MOSFETS and other high power components and thus be more capable to run for extended periods at their design ratings. Keep the load well below the specified rating and chances are you will get by just fine.

@Leonb that is crazy. Doesn't make any sense whatsoever. Do you have a ghost looking over your shoulder? LOL. The only way that I could explain it is if your wiring system that you measure is very high impedance, i.e. not really connected but picking up AC through stray capacitance and that that would create a voltage divider with the body-to-meter resistance. When changing the probes, the capacitive coupling will likely change. No, I don't know what is happening in your measuring setup. If you would tell me 1, 2 or 3 volts difference, maybe. But 90V?? It's the weirdest thing I have heard in a long time. Ghosts in the machine.

I didn't follow this tread and will leave others to comment further. However, I saw you reference a surge protector and gave this link: https://www.takealot.com/united-electrical-16a-high-surge-protection-3-pin-plug-top/PLID72796115 In theory, a surge protector is a good thing, but these plugs are a TOTAL waste of time and MONEY. Others might disagree. As far as I know it is an Ellies product. The first problem is that it use a MOV. (Metal Oxide Varistor). These are round disk-like components normally blue in colour but sometimes also a yellowish or red. They are cheap components that degrade over time and become ineffective. The right component that SHOULD be used is a Bipolar Transorb which is very, very fast. Transorbs do not degrade, but they can blow up if their max power is exceeded. A real surge protector would require many components and might even use a gas-arrestor. The transorb is fast, but cannot handle sustained power absorption. A Gas-arrestor is slow, but can dissipate power over longer duration than a transorb. In combination, the weakness of one is the strength of the other. So its a good combination to use. A bit of a serial inductance would help in slowing the sharp rise-times of transients. MOVs are used in most equipment, simply because they are cheap and give ***some*** protection. OK, so they give some protection, so why not use a plug like that? These plugs have been designed by an IDIOT !!!! The MOV sits in the deep recess of the plug and uses spring contacts to press on the rear of L & N prongs. The problems are many: 1. The spring is made of thin wire which just can't handle any decent amount of current 2. The spring is a spiral. It is a coil and thus will have inductance. You do not want an inductance in that pathway!!!! 3. Being a spring, it will be made of some sort of steel (spring steel) which will have a relatively high electric resistance. 4. The contacts are just spring loaded and are bound to have much higher resistance than a proper screw or clamp termination. Perhaps someone has redesigned the product. Running thick wires from the MOV and terminating them with the cable would be a good start. But I doubt it. People that have these plugs can open them up to see if the construction is still as stated above. I am out of touch with prices, but in quantity, a MOV might cost R3 to R5. A transorb maybe 10x more. Transorbs must be carefully specified for the voltage. You get transorbs that snub as low as a few volts. For AC you need a device that is bipolar and clamps at about 340+ V. One would need to reference the datasheet. They come in 600W and 1.5KW ratings and look like a diode. I am sure you will also get much bigger devices rated for even higher (instantaneous) power handling.

@P1000 I would hope that some sort of hardware watchdog would be implemented to prevent this. A DC-only output, as well as large DC offsets on top of 230VAC would be the end of any wound component such as a motor or conventional mains transformer. SMPS supplies would normally not mind DC or DC+AC as long as the voltages are not too high - and not too low.

Fuses are installed to disconnect power from equipment that went faulty. This is to protect the equipment from more catastrophic failure and potential fire. In your case we can assume that your computers, till, etc. are NOT faulty. So what other (outside) factors could cause the fuses to blow? I can think of the following: 1. Continues over-voltage, you can rule this out if you measured the output voltage correctly; 2. Very high voltage transients - normally less than a few milliseconds - a multimeter would not register these; 3. Very high harmonics riding on top of the 50Hz AC sine wave - for instance from so-called modified Sinewave Inverters - your 5KVA inverter is a true sinewave inverter, so no, very unlikely. 4. A large DC component added to your 230VAC output. Let me explain point (4). Imagine that by some very, very strange wiring fault, you would connect your 48VDC battery in series with your inverters 230VAC. Chances are you would blow up the inverter, but depending on the inverter's topology such as fully isolated DC/DC boost inverters, etc. one could maybe get it right. If you where to measure AC voltage, you would measure 230V. The meter would ignore the DC component. If you where to measure on DC, your meter would show 48VDC, ignoring the AC component (your meter might also not like this). Your equipment would see very excessive voltages and would certainly start sweating, or get ready to release some smoke, entrapped within the components. I have mentioned point 4 for completeness sake. I don't for a moment consider this a likely or possible situation. However, I like to throw my net wide open.... at least it is food for thought and could trigger someone else to get an ah-ha moment. So in conclusion, point 2 is the most likely. But why? How? Well, I don't know, BUT seeing that you did the installation yourself, make sure you have a good earth to your inverter. This is the 2nd time today I mention earth as a possible culprit. During switch-over, you are for a moment in a no-mans land until the relay contacts have slammed over. A bad or no earth connection would allow for possible (or much larger than normal) inductive or capacitively induced spikes. Electronics make extensive use of negative feedback control loops, to keep the system stable. This requires good earth references.

You obviously have an electrical leakage problem somewhere. The question is, is it inside the inverter or outside? Outside would mean (1) your house wiring or (2) auxiliary electric or electronic add-on modules that form part of your inverter system (communication interfaces, isolators, fuses, monitoring devices, etc). My highest suspicion is on house wiring. For example, old houses often have their light circuits **NOT** connected to the earth-leakage unit. When you powered the house from Eskom in this instance, you would never have been alerted. An inverter however, might have purposeful monitoring circuitry, or it might inadvertently be effected by leakage. Leakage inside the inverter is highly unlikely, but not impossible. Firstly your system is new, and secondly you have TWO inverters. They will not BOTH pick-up internal leakage. Internal leakage is possible if any foreign matter gets inside. For instance, ants could carry crap into the unit. Once the air gets moist, this could interact to become a somewhat conductive layer of dirt and leak across PCB tracks, etc. In military electronics and very high grade commercial equipment, PCBs are conformal coated. This is a type of lacquer coating that is isolating and prevents leakage. But conformal coating can be a huge nuisance when PCB fault finding and repairing. The application would also dictate possible conformal coating. For instance, micro-inverters live in un-kind environments and are thus very likely to be coated, or even totally embedded in some rubber compound. My advice is as follows: 1. Ensure that your inverters have a good reliable earth. An unreliable or missing earth can cause all sorts of strange effects. 2. Try to isolate certain circuits (i.e. switch off certain circuit breakers) and see if you can eliminate the problem in this way. If you know which circuit gives the problem, corrective action can then be taken. The most likely culprits are junction boxes and outside light fittings where there is a good chance of ants, wasps and any other creepy-crawly from building nests or leaving droppings.

Wow, within 2 hours a lot of comments.... you guys are obviously not retired like I am. Retired people are busy and don't have so much time to read and respond to messages. LOL. Some interesting comments. This is how I see it: @TaliaB is absolutely correct that modified sine wave inverters have very poor THD and high orders of harmonics. These high frequency components are not doing anyone any good. These frequencies radiate (using your house wiring, extension cords, or whatever wiring you use to get the juice to your load), they cause EMI/RFI noise that can affect audio, visual and communication processes. What is also REALLY bad is that these high frequency components can cause extra heating in motors and many other wound components such as transformers. Extra heating firstly wastes energy that must come from somewhere (your batteries) and it will quite possibly lead to failures or at least reduce the life-expectancy of equipment. Just don't ever use a modified Sine inverter to power motors. That will simply have a bad outcome. Transformerless power supplies use a high voltage bipolar capacitor to act as a serial impedance that will drop the supply voltage. Typically they use 220nF to 680nF depending on how much current is required. During design, one assumes that the input is a (true) sinewave of known frequency. The capacitor will have an Impedance Z = 1 / [2*pi*f*C). So a 220nF capacitor at 50Hz will have a impedance of 14 468 ohms. As this impedance is reactive, it will effect the power factor but will NOT waste power as heat (unlike a resistor). If the applied AC is no longer a proper sinewave, but this "thing" that looks like a square wave with a dead period in between, those high freq. harmonics will reduce the capacitor's impedance and put the typical zener diode that follows the cap under strain. If the device contains a small microprocessor it might only need 1 or 2mA and use a 220nF cap or less. Those circuits I would expect to be OK. If the device has to drive a high number of LEDS (for instance a 7-segment display) or drive a relay (a geyser timer) then very large capacitors are needed and components are more likely to be stressed and over-stressed by modified sinewave inverters. Note that many, many low wattage (up to about 3W) LEDs on the SA market, use transformerless supplies. I do however agree with @P1000argument. Just about ALL modern electronics use proper switch-mode power supplies (SMPS). Here, the AC is taken through a common mode filter and X and Y-capacitors and some protective fuse/current limit resistor, or NTC resistor and then immediately rectified with a full-wave rectifier and smoothed. Cheap, low grade products will normally have the common-mode filter and X and Y-caps removed to save costs. Often provision is made for these components on the PCB, but not populated. Note that these filter components work in both directions. They protect the device to a degree, of any incoming spikes/noise and they also block switching noise from the SMPS to climb onto the feeding wires. I have a Lead Acid charger that doesn't have these filter components, and my PC speakers immediately start humming if I switch that charger on. Generally speaking, a SMPS should be fine with a modified square wave input. So why did those routers blow up? Well, firstly I think the router is still working but that the power supply packed up. My hunch is that the power supply might have an X-capacitor after a fuse. The X-capacitor sits right across L & N. It sees the high harmonic content and becomes warm under the collar... It's reactive impedance drops and might lead to the fuse aging and finally failing. It is ironic that a cheap SMPS that doesn't use the input filter components might be much happier with modified sinewaves than the properly designed SMPS that includes the input filter. It would be cheap and easy to repair such a SMPS, but that is no good for the end-consumer. If my above hunch is correct, it would mean that low-power SMPS are more prone to "blow" than higher powered SMPS. The X-capacitor doesn't need to be increased for a high-power SMPS. The higher reactive current due to the high frequency components over the X-cap, will be proportionally larger in a small power supply. The fuse will be dimensioned for the overall power take-up required and thus more likely to fail. I do not want to be an alarmist, but high frequency components on a less-than-decent X-cap can even lead to a fire hazard. A true X-cap is marked as such. There are strict requirements for these components. Just popping in a normal high-voltage cap to save a few cents is not a good idea. Stelzner is a US company selling "dirty" electricity "filters". These filters are nothing else than a large capacitor that is plugged over L-N. Some have caught fire. I would never use them. Noise should be reduced with LC (inductor/capacitor) combinations and not just with a capacitor alone. Modified sine-wave inverters are cheap and nasty. But they are the norm for low wattage inverters. The electric noise is a problem and as you might have seen me say elsewhere, have potential negative consequences on our health.

A 10+ year old CRT-based TV might look like this. CRTs use extra high voltages of 25KV+ and the resulting electrostatic fields act like a big dust magnet. Inverters don't have high enough voltages to be considered electro-static. My guess is that your installer might have placed the unit on the floor and then started to drill many masonry mounting holes right above it. The unit needs a proper high-pressure blow-out. Inverters normally use many MOSFETS in parallel to share the load currents. If one pops, it will put more strain on the others and then they can pop in a chain reaction. So yes, a short burst of machine-gun fire. LOL. Hopefully you find someone that can repair the unit. Spectacular blow-ups always have the potential to burn PCB tracks and depending on the extend of this, reliable repair is not always possible. A decently designed product should have gone through extensive product testing and should have multiple thermal protection. Both firmware monitoring and controlled shutdown as well as electro-mechanical thermal cutouts or thermal fuses should be implemented. CTek battery chargers are normally highly rated automotive accessories, but I remember a youtuber who bitterly complained on the build-standard of one particular CTek charger. Sadly, much equipment with high prices ride on some historic good name and there is no guarantee that workmanship and good design will forever prevail. The opposite is also true. Sometimes I come across cheap Chinese equipment which is astoundingly well made. As engineer, I normally open a newly acquired product BEFORE I even plug it in for the first time.... to see what crap I spend my money on this time, or how lucky I got. LOL. Inverters are often installed in garages and other less-than perfectly clean environments. So we should always consider the possible attack by creepy-crawlies or worse, rodents. Even an army of tiny ants can cause problems. Might be a good idea to place a few moth-balls in close proximity and do a visual inspection every 3 months.

Once you have your busbar cut and drilled, I would tin them myself. Just heat it with a mini-torch and apply flux and solder that the plumbers use. Once cooled, wash the flux residue off with soapy warm water. Plating would only make sense if you need to produce a large number of bus-bars. As to obtaining the actual copper.... Mmm, ask your friendly contact working at an Eskom power station. I am sure they need some reason for their next sabotage.

@Scorp007 You are correct, the power plugs are a problem. On my Lenovo miniPC I had to resort to buying a spare charger just to obtain the correct plug & cable. An expense of about R 300 which I will pay any day for the luxury of having an always-on system that is noiseless and has basically zero idle consumption. Small inverters of 2KVA or less are normally either of very poor quality or prohibitively expensive, at least when compared to say, a 1KVA or 3KVA Axpert Inverter.

Most people, especially end users, have barely a grasp what an inverter is, let alone understand that these devices are not very efficient. 20 to 50W idle consumption is not uncommon. So to put this in context, if the end-user wants to run a laptop and a WiFi router, then it means the the inverter can self-consume as much precious battery power than the required load. This is a frightening thought, considering the expense of the batteries. The above reason is why am so against inverter use. There are many, many instances where an inverter is not warranted. The problem is that nobody provides inverter-less solutions, and yes, there are some hurdles to overcome. Sadly, there is no plug and play solution. @Chris_h, I would like to refer to your Juicebox as an ACJuiceBox. At R8750 it is very good value, I think your margin must be quite small. There are many commercial products that offer similar performance. Many use Lead Acid batteries which is obviously not ideal. I propose that you, or someone else that has the time and wants to fill a gap in the market, makes a DCJuiceBox. I have yet to see such a product. The DCJuiceBox would be similarly packaged but would NOT come with an inverter. Instead, you would mount two Boost regulators that are pre-set to output 19VDC. (These typically cost R100 each.) You would also include two cigarette lighter sockets for raw battery voltage and some high current USB sockets. Individual outputs should be switchable (so as to reduce quiescent current consumption further, by turning off circuits that are not required). Cheap and readily available car fuses should be used to protect the 12VDC outputs and also the various regulators. Most laptops run from 19VDC. Many PC monitors as well as miniPCs also use 19VDC. And a few 32" and smaller TVs (Samsung for instance) run from 19VDC. More and more electronics make use of USB chargers and you can get 3W and 6W 12V spot-lights. Set-top boxes and routers are normally rated for 12VDC as well. Yes, a charging battery can go up to 14.5VDC, it ***SHOULD*** not be a problem but one cannot say with 100%. I personally would not hesitate to power a set-top box from say 13.5VDC as they all use further switching regulators. To be on the save side, one could add 2 or 3 silicon diodes in series with the output. In charging mode, these diodes are left in circuit, when the charger is done, a relay could short-circuit the dropping diodes. Or one could forgo the power loss and leave one or two diodes permanently in series. Still better would be some voltage monitor that could switch a relay or MOSFET, but that would add some cost and might not be so easy to source. A DCJuiceBox is certainly not for everyone but it would be good to have such an option available, at least for those user that are a bit tech savvy. The cost savings on the inverter, battery savings or longer run-times (when using same batteries) and silent (fan-less) operation are all huge advantages.

@BritishRacingGreen You are absolutely right. A negative battery terminal does ***NOT*** make a convenient ground connection (!) The equipment should be grounded at a manufacture provided and clearly marked ground connection. Furthermore, only one earthing point should be used. If multiple earth wires are used, they are bound to produce fault currents and this is not ideal. In theory, there should be no measurable current in an earth wire. In the real world things are often different. High voltage AC will produce capacitive and inductive coupling. The installation guide should always be referenced and all warnings therein be heeded. Sadly, with cheap Chinese and clone equipment the documentation is often cryptic and unreliable and sometimes missing altogether. As to qualified and competent people.... one would hope that the majority of such know what they are doing and only a small minority are cowboys. Assume the inverse to be true. Assume they are all cowboys, until proven otherwise. This comment is not directed at this industry or even this country, but ALL professions. Plumbers, engineers, doctors, motor mechanics, lawyers, etc. Often, the qualified and competent are mutually exclusive. Nobody should implicitly trust ANYONE but try to educate oneself and at least learn to ask the correct questions. This has never been more important than in this new World 2.0 where the truth is labeled as false, misinformation and actively banned, hidden and deleted. If you don't believe my last statement, consider that in electronic communications such as in a serial SPI bus, the word Master and Slave are now considered political incorrect words to be avoided. The world has simply gone mad.

You could also try Altron Arrow. https://altronarrow.com/passives/ Check Dataweek or Pulse Buyers Guide for other passive component distributors. I think the near demise of the whole Denel Group will have caused a lot of death and destruction in the local electronics supply chain.

I have never heard of a 3900uF cap.... LOL. You can try Electrocomp They have a 4700uF 100V 105degC listed here: https://electrocomp.co.za/product/electrolytic-cap-snap-in-4700uf-100v-105c-vishay/

On high voltage equipment (i.e. mains) earthing is a vital protective measure. A person touching a live part will cause a fault current to flow to earth/ground which can then be detected by the earth leakage protection device. However, it is ALWAYS a good idea to earth electric equipment, even low voltage 12V / 24V stuff. With low voltage it is not for safety but to prevent, or at least **reduce** noise radiation. All chargers, inverters, etc. use switch-mode power supplies that typically switch at around 40 kHz or higher. The switching devices produce a lot of switching transients (harmonics) that radiate EMF/RFI noise which can cause noise interference on audio equipment, noise on video, and could (potentially) even effect digital communication and processing. (The noise can stretch into the many 100s kHz and MHz regions.) A certain amount of switching noise will also be carried by input (battery) and output DC/AC wiring, and the house wiring then acts as a massive antenna for this noise. This is normally referred to as "dirty" electricity. Such radiation could also be detrimental to human health, although nobody wants to believe it.... Equipment is normally enclosed in steel enclosures or aluminium extrusions. Due to the various holes for connectors, fans, cooling slots, etc. these enclosures are not perfect Faraday-cages, but still help substantially to prevent the equipment from radiating. To do so, the metal enclosure should be tied to ground. A true Faraday cage will do it's job even when electrically floating, however, due to interconnects and stray capacitance it just works much better when a reasonable low impedance earth is provided. Most power electronics, as indeed any modern electronics, use negative earth. However, with power electronics, the lazy designer, or budget conscious, often place the shunt resistor (to measure the current) in the negative output line. Even if you measure with a multimeter, it will seem that input and output negative terminals are linked, when in fact, there (might) be a 0.1 ohm (or lower) resistor between these terminals....

SARS will make ORDERS more on the VAT they collect (from your typically installed inverter, battery & solar panel system) than the misery 15K MAX tax rebate on the panels.

Sorry Desulf is at startup only. Not end of charge. But pulse charging should be avoided as well. I am no battery expert, but what is interesting is that if you put LiFePO4 in storage, the recommendation is to do so at approx 50% charge, not fully charged.

Firstly long term float charging is not advisable on LiFePO4. However, seeing that these Nova's are SLA drop-in replacements I guess that means that their internal controller has a way of dealing with the issue. What I actually meant with my comment was to disable charging BEFORE the charger ***ends*** float-charging and (possibly) enters Desulf handling. Just because you cannot see any behaviour that looks like a Desulf algorithm doesn't mean that your charger might not attempt such a state under other conditions linked to time, temperature, length of non-interrupted battery connection, etc.

Ha, Superfly. Good luck with disassembly. It would take a hundred years. The control board must have about 50 wires. A lot of logic will be used to drive the ice-maker and cold water pump/disperser. In my younger years I tried to reverse engineer a IDS 1200 alarm panel based on a 8051. the decompiler allocates random, meaningless labels... anything is possible.... breaking one's finger in you-know-where too. No, disassembly on such a complex board with many other main functions is not worth it. There is a UK company that fixes fridges. They have developed their own power logger to debug the fridge's behaviour. These guys sell kits to take over the defrost cycle. But I don't need kits. First I need to try and fix it properly. If unsuccessful I will give it the McGyver treatment. One can buy simple programable timers and I need to see if they do the trick. Or maybe buy such a timer and re-write the timing loops from scratch. These sort of devices normally run on a little PIC. It will still consume a few hours... Why do you want to change original Samsung firmware? Surely firmware that was working for many years should be good for a few more? Yes, you can MASK a failing sensor in software and create some bypass. But rather find the misbehaving sensor and replace it.

These Nova's are designed/sold as SLA drop-in replacements for items such as gate motors and alarms. I agree with Scorp007, if you keep watch and switch off during float charge cycle then no problem. We need an enterprising youngster to take a cheap but "intelligent" lead-acid charger, backtrace the main circuit IO lines, then dispose of the embedded firmware and write new firmware for a proper LiFoPO4 charging algorithm. The hardware should be 100% compatible with both battery technologies.

Yes, Samsung with LCD display. Youtube is full of people complaining and they all have the same problem I have. However there are many points of failure. Heating element could be open circuit, mine is OK. Then there is a thermal fuse, checked that, that's OK. It could be a temperature sensor. My frost temp sensor is working, but I know there is another sensor inside the cooling ducts and THAT sensor doesn't seem to want to change.... heating the panels with a hair dryer makes nothing to the measured resistance. Not sure what to do about it. And then you have a A4-sized controller PCB. What a nightmare. Obviously the relay or SCR or MOSFET that switches the heater could also be faulty. My fridge must be about 10 years old. You are looking at 18K replacement cost. So there is a strong urge to fix it. Even if I do a McGyver on it. (implement a small uP timer that ignores all sensors and manually switches the heater on every 12 hours).

Cheap SA fridges are old school and super simple. Good for our country. As soon as you go for Bosch and Samsung the nightmares begin. My Samsung double door is now off for the 4th day, waiting for yet again a defrost. It has too much brains and now refuses to co-operate. These fridges have defrost heaters. Mine uses a 140W fridge defrost element, and I am not sure, but I think the freezer might have another heater as well. I am foaming at the mouth, with having to deal with icing up every two weeks. Some Samsung fridges have 240W heaters. However the heater and compressor are not run in unison. But the blik-brain does run the compressor longer and over-cools the fridge, before then going into a defrost cycle with heaters blazing. I am convinced my fridge never turns on the heater, thus the investment into a current/power Arduino datalogger to find the truth. Point is, you get a very wide spread of fridges.

I would expect Circuit Breakers to have a bit too much of a spread to use them as a reliable abuse avoider. But in case you do NOT want your tenant to use heating devices such as kettles and microwaves it can work.