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Thank you for the great forum, Safe Driving over the weekend. Sincerely Jason

PJJ

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PJJ last won the day on February 10

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  1. Also I would not recommend you do a install without a MPPT. If your system had a shutdown event (lets say you hit minimum SOC) and the AC falls away there is no way to start the PV Inverter again (Because it needs the AC from the Multi to couple to) so you would sit in a deadlock position where the sun could be shining but since your batteries are too low to start the AC Inverter, you also can't by proxy start the PV Inverter.
  2. Very true, if I look at my house consumption 80% of the time its below 500W, with only peaks when things like the Geyser and Stove start chugging away, that's probably why I was able to get away with a single 800VA Multi for so long. My problem however was if both the fridge and chest freezer compressor both came on at exactly the same time I would trip the little Multi (It only happened like twice, both times after they were left disconnected for a while and reconnected back at exactly the same time) those compressors have insane startup current. But since I have the second 800VA unit on the wall its never been a problem since.I can also now for the first time ever use my pressure pump when the grid is down, its a 0.85KW pump. At first I wondered whether it would be worth it to add the second Multi, but when loadshedding started again and I had to forgo a few showers the decision was easy.
  3. Not necessarily, if you go the Axpert route yes, but If you buy a Victron or Goodwe you can feed in excess solar power (granted while the grid is on) to those loads, without worrying about a big load taking your system down in the event of a grid failure.
  4. The problem with going off grid is generating that last say 20% of your needs. If you stay on the grid, with a decent battery bank you can generate 50-80% of your power needs without blowing the kitty. But that last 20% gets exponentially more expensive to supplement, its definitely not linear. Also like Macleod pointed out, financing, you might have R50K in savings somewhere you can raid for a nice on-grid system, but R100K+ would see you having to finance a portion (or all for that matter) and capital is a finite resource.
  5. I am not a member on any of the 4x4 forums, but I remember stumbling onto a thread one day on some SA 4x4 forum, and the one guy had the perfect idea for a perpetual motion machine, other members tried to explain to him that it wasn't possible, to him the law of thermodynamics was just a annoying law soon to be legislated away IIRC he also drove a Land Rover, make with that what you will .
  6. PJJ

    Solar quote

    How exactly is 5.4KW worth of panels considered 19.5KW? I don't see a generator in there? If its truly a off grid setup (No AC available) then you definitely need a backup generator, that solar array will on a bad weather day only generate around 3-5kWh for the whole day and you will be sitting in the dark. I would say to even consider "Off grid" you would need a backup generator, and double that solar array. Edit: I realize that you didn't say its a Off grid setup, I simply inferred it from the quote.
  7. Fun fact about these, the amount of air changes required will be dictated by the maximum CO2 concentration you would want on the inside of the building. So the best way of actually designing this would be to have a CO2 sensor inside the building monitoring ppm, once the concentration goes above say 600ppm you start ventilating, once you reach 450ppm you stop. But the reason why I think we have bigger systems in the first place is because our mall experience is different to the ones in the developed world, in the developed world, you have fewer shoppers going to more malls, but each shopper also has much higher purchasing power than the average South African shopper. So fewer people with more money = the same as more people with little money. But having more shoppers = More CO2, and that CO2 needs to be taken out, whatever they are spending R10 or R10K at the mall. I saw this firsthand in the US, the malls where quite empty compared to what I am used to, I don't know how it is where you guys live, but here in Limpopo, if I go the local mall over a weekend the mall is guaranteed to be packed, however its mostly just people coming in to buy 1 shirt, or even just to buy a R15 Pie at the King Pie in the middle of the mall.
  8. Now that is Savage! I'll see myself to the punitentiary
  9. You should! You could also even cover the potential role we solar + storage folks can play in helping with grid services
  10. Sorry if it wasn't clear in my post, but that is exactly what I tried to illustrate, its not the capacity of a single home that is the problem, its this added load that potentially thousands of inverters could all add to the grid following a loadshedding event, on top of the already big strain the system would face from just geysers/fridges etc all kicking in as well.
  11. Well you could but you won't, because your demand would be whatever it was before. (predating your install) In the install that I mentioned earlier where the AC Input limit works so great, that house never had a event where the main breaker tripped due to drawing too much power. But after the install, maxing the 70A charger of the 5kVA Multi you will see that your grid power draw now goes up by a additional 3.7KW+- because of the AC Charger. Now multiply that by potentially thousands of homes and you will see that you might have a peak demand problem right after a loadshedding event.
  12. I don't think people realize how much 3.5KW is, its plenty, I ran all my house lights, networking equipment, TV, 1 PC and fridge on a 800VA Multi for 2 months with no issues. Of course I made sure the killers (Microwave / Kettle / Hairdryers) where kept away, but I guess one man's non-critical load is another man's critical
  13. Its also VERY useful in preventing you from accidentally tripping your mains supply in a house with big loads and charging batteries after a grid outage. We have one farm house with 2x Big geysers elements multiple aircons, swimming pool pump etc, and watching the Multi throttle its AC charger to ensure it keeps within the AC input Limits (Or even take power from the DC bus with power assist) is a thing of beauty!
  14. Its only on the AC Input side, as stated above, once you are islanded the sky is the limit.
  15. It definitely is. As the saying goes: Everyday I know more and more about less and less. Edit: I just realized now, I only mentioned the Mandelbrot set, the video covered : the logistic with its connections to fluid convection and neuron firing, definitely worth a watch.
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