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I am planning on getting an off-grid/hybrid power system for my house. We have a shortage of inverters in South Africa currently.

Is it possible to have 2 inverters in parallel: one of them 48 V (5 kVA) as primary and another one a 24 V (3 kVA) as secondary?

Fred
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zunetastic
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1 Answers1

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No. If your battery system is 48V the 24V one will break, and if your battery system is 24V the 48V one won't work.

If you just want a spare one, in case the first one breaks in an emergency - then having the wrong voltage might be okay, but it will be very inconvenient because you'll have to rewire your batteries to get a different voltage. That might or might not be possible, depending on how many batteries you have and which type.

Off-grid inverters will break if you connect the outputs in parallel. If not for the voltage problem, you could put the inputs in parallel, but you'd still have to keep the outputs separate. You couldn't wire them both to the whole house - you could wire one to one part of the house, and the other one to a different part.

user253751
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  • Its going to be 24v lithium iron batteries . two to start with. the plan is to have the inverters in parallel. – zunetastic Jul 14 '22 at 10:31
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    @zunetastic so you have the ability to wire them in series for 48V and in parallel for 24V, but not both at the same time – user253751 Jul 14 '22 at 10:31
  • well the reason for having two is that the cost of a 7.2k single inverter here in south africa is more than buying them separate. and as a spare just in case the master one fails. – zunetastic Jul 14 '22 at 10:49
  • @zunetastic have you considered reducing your energy usage below 5k? – user253751 Jul 14 '22 at 10:50
  • @zunetastic or getting the right voltage inverter - see if someone else has a 48V inverter by mistake, for their 24V system, and you can swap (assuming that you are going with 48V) – user253751 Jul 14 '22 at 10:51
  • well most of the day it is below 5k. but in the evenings, with the water heater and the ovens on duty, I dont wanna deal with the inconvenience

    I suppose for now until I can source another 48v inverter I will start off with the one.

    Thanks @user253751

     – zunetastic Jul 14 '22 at 10:54
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    @zunetastic Be aware you have other options for water heating. Heating by solar panel and inverter - that's a bunch of equipment just to make heat that the sun is giving you almost for free already! Solar water heater panels use black tubes filled with water and the sunlight heats them up, and a glass cover traps the heat. – user253751 Jul 14 '22 at 11:21
  • Or you could try running your water heater on DC, if you're up for a strange DIY project and voiding your warranty and home insurance. Heating elements can take any kind of electricity, but if it's designed for 240V then 48V won't make nearly as much heat, but maybe the water still gets hot enough if you heat it constantly all day - I don't know. Or maybe you get a heating element designed for 48V. – user253751 Jul 14 '22 at 11:23
  • Yes yes, that solar water heater/geyser (with the black tubes :) ) sounds like a good addition. Something I will definitely consider – zunetastic Jul 14 '22 at 11:26
  • @zunetastic there are also solar ovens but I doubt you want to go that far. I think most people with solar power systems do end up trying to conserve energy, because the energy feels expensive when you have to pay up-front for the equipment to make it (instead of just paying for the energy). It occurs to me an electric oven is also mostly just a heating element and therefore it should be possible to make one that runs on 48V DC (thick wires though) but that's also pretty extreme. – user253751 Jul 14 '22 at 11:36