SilverNodashi

I read that article with, well, horror. So they want to monopolize something which should have enabled the poor and destitute to some electricity as well. Why are PC's and PC software so expensive? Cause Apple set a standard and the rest either had to keep up of fall away.

Aah, didn't realize you want 105 degree ratings. Why though? Does it really get that hot, or are you upgrading?

please do share the link if you manage to find it. Perhaps ask the supplier (Mustek?) for the firmware, explain to them that you need them all to be on the same version in order to stack the inverters.

I'm sorry but you just lost me. You want to tie an inverter output to another inverter output, to disconnect from the grid? You only need a one inverter and some PV to disconnect from the grid.

I actually want to go the micro inverter route as well but already have what I need. The one nice thing about micro inverters is that you can add as many as you have cash for. It's a GTI setup, with the advantage of easy / cheap growth and much more redundancy. If one or two panel / inverter pop, you still have the rest. If that big 5KW GTI pops, you have nothing. The Renesola micro inverters have anti island protection built-in already. But you're right at some point a GTI is cheaper.

So, you're saying I'm wasting money on my bigger system, by using Eskom as a standby? On the farm we have a genset as standy since there is no Eskom. With the 3phase equipment we have it's a bit difficult to split the systems as have been suggested above. And it's a bit difficult to switch non essentials on a game farm which requires 10,000L water pumped from the well for the animals every day.

It's not just that company. Just about anything which is main stream is generally double the price in a 12V version - even though just about everything runs a DC bus in any case. For example, 10W, 200V flood lights can be had for about R100. 12V equivalent is R200! I won't even go into the dynamic of manufacturing these devices.... A camping fridge cost say R12,000 whereas a bar fridge is R2,000. Ironically though I met a guy some time ago who build those camp fridges and sell them for R4000. He sells the exact same fridges to three big chain stores, who rebrand them and sell them at R12,000! Makro, for example, sells a 250W solar panel for R7K. Builders used to as well but the prices came down to R4.5k Why not? It's cheaper than the blue stuff Well, here's where it gets interesting, to run everything as efficient as possible. How do you deal with this conundrum?

R25K for a fridge, some panels + MPPT + battery! I'm sure I could do the same with my R8K fridge. R17K will get me 2 x 250W panels (R5K) + 20A MPPT (R2K) + 105A battery (R2K) + cables (R500) + 1Kw inverter (R4K) + pizza and plenty food to fill the fridge (R3.5K) Or I could install an Axpert and have Eskom backup as well. For when the cheap-ass battery dies and it's too cloudy for three days to keep the food frozen. And then I could add another fridge to the same system, at only the price of the fridge itself. And even run some LED On the subject of modified inverters, I know my fridge can run off a 1Kw modified inverter

You need a COC as soon as you make changes to your electrical wiring. You could get away with it, when you sell your house and take everything out. But you won't get awat with it if your house burns down and your insurance doesn't pay out cause there's no valid COC. SO, if what you're powering isn't connected to your house's wiring, you might get away with it. If it's mobile, you definitely don't need a COC. P.S. you don't need a COC for a UPS, since it's not hard wired into the DB board, but the moment you hardwire it into the DB board, a COC needs to be signed / amended.

From experience it isn't always possible, or easy or cheap to go split systems if you want valid COC's. Many sparkies will argue that you need to run a separate DB for every feed to the house. Some will say that as long as the cables / CB's are physically split and labelled properly it's fine. But then you also need a seperate isolator and earth leakage for every set of CB's. Lights can probably go without an earth leakage but I know many sparkies will fail the COC if that's the case.

Here's the problem: Most (non technical) folk are overwhelmed by solar systems. A single system is already a big learning curve for them. Now you want to give them 3 or 4 systems to monitor / maintain and worry about. Running a gate motor, garage motor, alarm and electric fence is a no brainer. Use larger batteries to carry you through the night (7Ah is often just not enough) and a 50W panel, and you're "a-away". Running a fridge off a 100W panel + battery is also very doable. Running your router + laptop off a small panel + battery is also very doable. The bigger loads, like pool pump, dish washer, tumble dryer, etc, etc, all require a bigger system though. If you run these items only during the day, on an off grid inverter, batteries are not necessary. Unless you want / need some backup to cover cloudy days, or as a buffer on a windy / rainy day with clouds moving around the whole time. P.S. How do you think big roof top installations on malls are setup? Pretty much the same way you're trying to do it here. But they use some nice equipment that's built for that purpose.

I've "seen the light" a long, long time ago already. Speaking my mind here is different. My dad's house' load used to be split like that. The cost of the extra cable was probably not worth the savings on the inverters. But now he has a couple small battery banks which don't all need to be replaced at once.

There's a reason why it's easier / safer to go with a bigger system if the need requires it. OR, split the loads in the DB board. i.e. run all your lights (will probably be less than 150W, depending on your house) on one inverter + battery + charge source, the TV + PC / etc on another, and anything else on another. You could probably run the fridge, garage motor and alarm / electric fence together with the lights as well - see this as "critical load #1". TV, PC, cellphone chargers, etc, as "critical load #2", and pool pump / electrical tools / etc a "no critical load" This way you could also salvage and mix batteries. Your lights could probably run 3 times longer (in terms of cycles) than the rest of the same model battery.

Can you see these?

yup

hehe, it would be fun! DC volts don't charge phase (not 100% correct, but I'm trying to bring across the message) between positive and negative. Thinking back to science class you learned that electrons flow between negative and positive, right? Those electrons don't ever stop flowing, unless the circuit is broken. Anything in between (resistor / LED light / motor / buzzer / etc) will keep the electrons flowing. When there's more volt & amps, more electrons flow. Think about the municipal water coming out of the tap at about 3 or 4 bar pressure. That's similar to Volts in this case. The amount of liters you get per minute is similar to Ampere. You can make less water running, but the pressure will be the same. So, at 12V you can have 1A or 100A. Current is "drawn" and not pushed. i.e. when you connect a light 10W bulb it only will draw 0.83A current. A 100W bubl will draw 8.3A. And a 1000W bulb will draw 83.3A. Simple math. Let's forget, for a second, about inefficiencies, volt drop, etc. Now, if you draw 83.3A from your 12V battery, and connect another 12V battery, that 83.3A gets split between the two batteries - google " current divider law". Let's use water as an example again: Imagine you want to water your garden and open the tap, you get say 100L water/minute at 3 bar. You can reduce the amount of water/minute by adjusting the tap, but the pressure stay the same. At 4 bar, for example, when the tap is open and you connect a sprayer to the hose, you get a lot of splatter. Now, imagine doing the same with a hose connected to a pool pump. MUCH more splatter. In fact, you'll probably battle to fit the sprayer while the pump is running. This is what happens when you connect / disconnect a DC power source to a load. The bigger the power source, and the higher the current being draw, will determine how easily it is to connect / disconnect it safely. Chances are you will just see a big arc and burn the cable / terminal / bus bar a bit. BUT, on disconnect, you might actually ^arc^ weld the cable and bus bar, or the terminal and cable together, causing it not to disconnect. An AC circuit on the other hand changes phase between positive, zero and negative. It does it very very quickly though - 50Hz (50 cycles per second) so the current drops (albeit very quickly and for very short periods of time) and doesn't cause this phenomena to happen. Check this out: P.S. I'm trying to explain this in laymen's terms, so please forgive me if you're an electrical engineer - the right stuff is sometimes too difficult to understand or explain.

You're still running DC volts and Amps - the source doesn't matter too much. BUT, and try this at your own risk, if the load is connected already (i.e. inverter + light and fishtank on), and the load isn't too high, it may probably not be an issue to add another battery. Once connected the current will be divided between the batteries. Could it cause damage? Probably. I don't have any unwanted inverters lying around to test with, so do this on your own. But, please share a video

While it's under the load? I don't know but I guess it might work? Or send your inverter in for repairs again it something pops

Move to Gauteng

Did you try Communica or Mantek? That CAP is fairly common. I'm sure even GT Electronics in Boksburg would have it in stock.

Nothing. You need to switch off / disconnect the load before you do it, so it's a manual process. This is fine if you can be there every time todo it. Something else that triggered my thoughts on this, I wonder if a dual battery regulator, as used in 4x4's would work in this case? The "national luna" regulator in my 4x4, as far as I understand, will charge both batteries when the engine is on, when the engine is off it blocks the 2 batteries. i.e. if there's a fridge connected and the 2nd battery runs flat, it doesn't drain the 1st battery. SO, what if it was connected in reverse, so that the two batteries could be charge separately, but then when there's load it engages both batteries. It has a 400A peak current so it would be fine for smaller installations. This whole idea is plausible and could help in using older & newer batteries together. BUT, batteries also drain at different rates, so I guess if you want to go this route you would need to monitor each battery and cut it off at a safe level as well. Off cause, if the research yield good results you could mix batteries, and in turn save some cash on batteries in the long run

please link to the specific article you found interesting?

DC volts & current isn't as "forgiving" as AC volts and current, especially when connecting / disconnecting. One way, perhaps, is to use a microcontroller (or PC / raspberry Pi) to momentarily switch off the load / inverter, then engage the SSR and switch it back on again. In theory most SSR's should cary many more Amps when switched, than it can switch under load. i.e. If it can switch 100A, it can carry upto 200A - https://www.futurlec.com/Relays/SSRDC30V100A.shtml SO, if your system is 12V and you thought of running multiple batteries in parallel, this could work with some careful planning and proper equipment.

The biggest problem you're going to face with this, will be to connect / disconnect the batteries under load. Unless off cause you don't mind shutting down the inverter every night and every morning to safely connect / disconnect the batteries. In my case, I simple can't be home at those times every evening and I can't expect my wife to be there either. I have seen a small system (4Kw) under slight load (probably 200w) blow 300A fuses on the 48V battery bank. Some ideas some come mind: 1) Use very big & expensive SSR's like this: http://za.rs-online.com/web/p/solid-state-relays/7761412/ 2) If the battery bank is in series (i.e. 4x 12V @ 48V) then you could connect a charger per battery. But you might have to put a "blocking diode" between each charger and battery to prevent any possible cross charge between the chargers.

I don't have a, or work with, morningstar. On that note though, many cheap PWM charge controllers DO have reverse polarization. So this begs the question: "Do the big guys leave it out on purpose, knowing some bloke will make a mistake, and then have to buy a new one"?