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3 Phase Solar Install Advice


Zapnologics

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Good day forum,

I am looking for some help / guidance.

I recently bought a house and upscaled from a small flat where I was running a Victron easy solar 2 (3000va) with a Fredomwon 4/5 battery with 6 * 320w Canadian Solar panels. I was lucky enough to be able to push my power back into the complex, and I probably exported 30% of my power (over the whole month).  

I was super happy with the setup and how it all worked. I left the solar panels at the flat and just installed a simple solis grid tie and took the Victron easy solar & battery with me. I have since managed to sell the battery to a friend as well. So I am left with the Victron easy solar 3kva.(this is solar, gx device and inverter all in one)

So now what?

My new house is substantially larger and is of course a 3 phase system (with a smart meter) so I can not push back. This adds all sorts of levels of complexity to the system, and I need some guidance as to what is the best route to go.

I have had a look at the db board, and thank goodness it seems to be wired very well (compared to what I have seen). So I think we can easily work with this.  (all the breakers which are down, are underfloor heating, which no one would date to use these days).  ( I have plans for the future)

Image of the db board:
20211114_190635.thumb.jpg.ef769348b2b5d7430cb7d83a66940fc0.jpg

 

Usage / Demand

Based on the previous owners usage they where using an average of 20kwh a day.  There are 2 * 200L geysers with geyserwise timers & thermal blankets. (I plan to keep the electric geysers, I don't want the cost and complexity of the solar ones). I will probably install 2kw elements in them, and rig a cleaver way to turn them on and off based on excess solar production.

The rest of the lights are all LEDs so there really is minimal usage there.

  • 1 * dishwasher
  • 1 * washing machine
  • 1 * fridge
  • 1 * kettle
  • 1 * microwave
  • 1 * electric oven (gas hob) ( we try and use the air fryer instead of the oven as it uses much less power)
  • 1  * gaming desktop (I work from home)
  • 2 * laptops
  • 1 * wifi, security cameras, alarm system, garage door, electric fence & gate motor.

Future additions:

  • Small Borehole
  • 0.5kw vsd booster pump for garden water.
  • Small fountain pump

Solar Panel Considerations:

So this is a big love / hate topic, I bought the house for its amazing setting and loads of old big trees, however this does not bode well for solar (at all).  I have worked out that if I remove one tree, I can probably make something work, Luckily now days solar panels are fairly cheap compared to the rest of the system.  So this will probably consist of 4 different arrays (all facing slightly different directions and will get sun at different times of the day. (this is far from ideal, but I really don't have much option here). This is something to think about on the mppt controller side. ( I'm hoping I can run multiple Victron chargers, one per array, so that it can each string individually track and optimize (especially for shadows).

Battery Plans:

Due to this house not being able to push back energy, I would certainly need to upscale the battery size. I am looking into the new Freedomwon e-towers, As they are more modular, easier to transport and still look to be very good batteries, I will probably start with 2 * 5kwh and then once the solar is up on the roof, I will look at getting 2 more, So a total of 20kwh batteries.  (this is probably still 2 small to go completely off grid / 0 consumption, but i'm hoping I can oversize the solar, and then get all the heavy power users like geysers, washing machines, dishwashers etc. to all run in the day, I should manage to get away with it.

 

Here are my thoughts (i'm open to other suggestions)

Option 1:
Sell the 3kva easy solar, and then build a completely modular Victron system with a multiplus-2 5000va. 

This would mean that I would essentially have to rewrite the house to be "2 Phase".  1 Phase being lights and plugs etc (equipment that always runs on the inverter) and then a second phase for all the geysers and heaters etc. (One generaly does this to some extent when you install a Inverter in a house). The only issue is the inverter would only draw from one phase. So if my solar all works well, there will be no load on phase 2,3 (from the mains box).


Option 2:
Buy two more 3kva multiplus devices and put one per phase and sync them up into a full on 3 phase system?

This is substantially more costly & complex and I cant see much benefit of this, unless I was running 3 phase motors in the house(which I am not) Nothing seems to be using 380v from what I can see in the db board? 

With this setup, I still wont be able to run 1 geyser of a single phase? never mind two and some other accessories.


I am interested to hear what other people have done?  I also pay a higher connection fee every month due to the 3 phase.  Does anyone know if its possible to  "Downgrade" their connection to a single phase 63A?

Having done solar before I really see the value of it, and I enjoy the environmental factor and self sustainability of it. So I am wiling to invest to do it right. I plan to add the costs to the bond.

I am a bit of a Victron fan boy, only because I have used it in the past and really enjoyed the configurability of it. I had an issue with the wifi and they replaced the unit for me no questions. But I am open to other more modern technologies, I was very impressed with the solid grid tie I installed in my old place.

 

Edited by Zapnologics
Added more info
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https://powerforum-store.co.za/products/goodwe-10kw-3-phase-hybrid-inverter-2-mppt-hv-battery

10kW inverter that allows you to have 100% unbalanced loads - so you can have up to 10kW on a single phase or 5+5 or 3.3+3.3+3.3 or any other sum <10. For the difference in price between it and a Victron system, you can buy a lot of panels+batteries.

Edit: apparently I misunderstood what 100% unbalanced means.

Edited by P1000
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  • 1 month later...

So after about a month if researching and googling, this is turning out to be way more complicated and technical than one would want.  Im very interesting tlin how solar installers would handle this. 

 

If you are going grid tie only its feasible, but if you wabt to go full hybrid setup things get complicated and overly expensive. 

Im tending towards rewiring the db board from 3 phase into single phase. 

 

But breaking it up into backed up circutis, akl lights and plugs, and then other. Like stoves, geysers, pumps etc. 

 

That way the solar can push back to the non essentials. Typically the high current use items while still backing up the essentials. This however does pose some limitations to how many geysers etc you can run with heaters etc.  However the goal is to essentialy reduce consumption, so having a smaller rated electrical system is not the worst thing. 

 

Alternatively, im gonna have to get a creative hybrid 3 phase / single phase mixture going.. 

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I have 3 phases coming into my house.

I added 3 Multiplus2 inverters (one on each phase), but i ended up converting my main db into single phase and ran the MP2 in series. Main reason was product lifetime. Running them in series meant there is more headroom for big spikes in usage, and if one fails i still have my other two that will pick up the slack.

The initial 3 phase setup was fairly easy to configure on the MP2s, and converting it to single phase was just as simple.

Personally i would stick to 1 phase, there should be no need for three phases on your house itself. It's easier to manage, and cheaper.
 

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1 minute ago, stoic said:

I have 3 phases coming into my house.

I added 3 Multiplus2 inverters (one on each phase), but i ended up converting my main db into single phase and ran the MP2 in series. Main reason was product lifetime. Running them in series meant there is more headroom for big spikes in usage, and if one fails i still have my other two that will pick up the slack.

The initial 3 phase setup was fairly easy to configure on the MP2s, and converting it to single phase was just as simple.

Personally i would stick to 1 phase, there should be no need for three phases on your house itself. It's easier to manage, and cheaper.
 

Thanks for this input.  I assume you mean you ran the 3 multiplus in "Parallel"  Ie  instead of 3kv per phase, you now have 9kva worth of power on a single phase?

Can you elaborate on how you mean its cheaper?  Did you actually convert you power connections with the main grid with Eskom from 2 phase to single phase?

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Just now, Zapnologics said:

Can you elaborate on how you mean its cheaper?  Did you actually convert you power connections with the main grid with Eskom from 2 phase to single phase?

No, they are in series on one of the phases coming in from eskom. they other two phases i use only for property lights :) 

Cheaper - Well, if i knew from the start i was going to convert my db to single phase i would not have needed 3 inverters. I bought 3, one for each phase, but ended up only using the one phase with all three inverters on the single line.

I have three phases coming into a main db on the plot, from there, it goes to each builiding, and i only converted my main house to single phase, which means i still have three phases coming onto the property, and i use three phases in my garage, but my house is just using one of those phases


 

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3 minutes ago, Tariq said:

@Zapnologics, what would Eskom charge you to convert to single phase and how much would your monthly admin fee drop by.

I have never done this, I do know the connect fee is lower for single phase,  However if you are using high amounts of power, I think 3 phase is cheaper on the power side.   But our goal is to use less power.  

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