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Starter System 3 Phase


JayN
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I want to install a starter system which I can build on with time.  My home has a 3 phase supply (no idea why), as my power consumption is only around 900kWH per month.

I am thinking of the following:

1.  Installing the Sunsynk 12kW 3 Phase inverter.

2.  Two strings of 4 solar panels each (500w+ panels).  I will grow this to 8 solar panels per string in time.

3.  One Pylontech 3000C 3.5KwH battery.  I will add to this over time, up to 3 batteries.

Whole house connected ... and anything that the system cannot provide will be met from the grid.  Obviously as the system grows, reliance on the grid will reduce.

Few questions:

1.  Is it possible to put in the starter system? Inverter, 8 panels and 1 battery.

2.  I am also looking for  installers that are not looking to change my mind ... or wanting to change my home to a single phase etc.  

3. Any suggestions from anyone?

 

 

 

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Just a few thoughts:

You can always convert your DB to use just one phase - this is what I did, I still have 3 phase but not using two of them. (although I see you mention you don't want to)

I have not really checked the specs on the 12 KW but I assume it would be limited to 4kw per phase. Although I see something about:

image.png.311393418c6fc2f125f5dbaa5c69a218.png

By moving everything to a single phase and installing a 8kw (for example) you can still support a "heavy consumer" versus having to limit your loads on each phase to 4 kw at a time and save some costs (although you can weigh up this saving against cost of converting your db to single phase).

Do you have prepaid? If so what type of meter?

One pylontech will not be enough to service the output your inverter can supply during load shedding - it can only do 50% of 3.5kw on a continuous basis.

(you can limit the power draw from the battery on the timer screen to 1800 watt to protect the single batter)

The panels seems fine, you will start saving money but of course it will not meet your demand of 900 kwh (especially if you use more in winter)

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you also should have a close look at what Pylontech have to say about the minimum number of units for 3 phase at 12kW. I do not know if they have any restrictions. Off grid vs Grid tie may also have minimum requirements.

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11 hours ago, branderplank said:

Just a few thoughts:

You can always convert your DB to use just one phase - this is what I did, I still have 3 phase but not using two of them. (although I see you mention you don't want to)

I have not really checked the specs on the 12 KW but I assume it would be limited to 4kw per phase. Although I see something about:

image.png.311393418c6fc2f125f5dbaa5c69a218.png

By moving everything to a single phase and installing a 8kw (for example) you can still support a "heavy consumer" versus having to limit your loads on each phase to 4 kw at a time and save some costs (although you can weigh up this saving against cost of converting your db to single phase).

Do you have prepaid? If so what type of meter?

One pylontech will not be enough to service the output your inverter can supply during load shedding - it can only do 50% of 3.5kw on a continuous basis.

(you can limit the power draw from the battery on the timer screen to 1800 watt to protect the single batter)

The panels seems fine, you will start saving money but of course it will not meet your demand of 900 kwh (especially if you use more in winter)

Thanks "branderplank"

I don't really want to make change in respect of the 3 phases.

At most I have 2 geysers and an oven (each on separate phases).  Stove is gas.  Pool pump is on the oven phase.  The rest are all lights and plugs - small stuff.  Kettle and iron are the next major current intensive appliances.

The inverter will do 6kW per phase independently (unbalanced load), subject to a max of 12kw across all phases.

It is a hybrid inverter, and so I would assume that if the solar panels are insufficient and the battery is insufficient, then the grid will provide the required power.  I am hoping this assumption is correct.

I'm not looking to go off grid, just looking to reduce my reliance on Eskom for now and then as I grow the system (batteries and panels) that reliance will get less and less.

I do not have pre-paid.  I'm on the Eskom system ... Landis 3 Phase meter.

 

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52 minutes ago, Sarel said:

you also should have a close look at what Pylontech have to say about the minimum number of units for 3 phase at 12kW. I do not know if they have any restrictions. Off grid vs Grid tie may also have minimum requirements.

Hi ... I will have to check up on this.  The inverter is a hybrid, so I imagine that the battery will provide some power (limited by the software of the inverter), supplemented by the grid.

Thanks for the reply ...

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Your system will work but if everything is connected on the UPS side of the inverter your battery will not be able to handle the loads which may be running when an unplanned outage hits you.

The part that is not clear to me is: "Whole house connected ..."

By virtue of the CT coils being placed at the correct position, the inverter will send solar power to your whole house thereby giving you a saving irrespective of having it connected to the Grid or Load side. So you will get the benefit of the sun.

But if the power goes out (unexpectedly), and you have all of these loads on the UPS side, I suspect that it would trip since the battery will just not be able to manage it (especially at night/cloudy conditions).

So maybe what you could do is leave two phases on the non-ups side (the ones with the geysers, oven etc) and have the lights phase on the UPS side.

This way you will make sure that the battery will only carry light loads during an outage. You can then later on move more loads over to the ups side as you expand your batteries.

Not sure if this makes sense to you. Maybe someone else has better idea or experience with this.

 

image.png.bac582bf8a76c7d462ff72ad13423528.png

 

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1 hour ago, branderplank said:

Your system will work but if everything is connected on the UPS side of the inverter your battery will not be able to handle the loads which may be running when an unplanned outage hits you.

The part that is not clear to me is: "Whole house connected ..."

By virtue of the CT coils being placed at the correct position, the inverter will send solar power to your whole house thereby giving you a saving irrespective of having it connected to the Grid or Load side. So you will get the benefit of the sun.

But if the power goes out (unexpectedly), and you have all of these loads on the UPS side, I suspect that it would trip since the battery will just not be able to manage it (especially at night/cloudy conditions).

So maybe what you could do is leave two phases on the non-ups side (the ones with the geysers, oven etc) and have the lights phase on the UPS side.

This way you will make sure that the battery will only carry light loads during an outage. You can then later on move more loads over to the ups side as you expand your batteries.

Not sure if this makes sense to you. Maybe someone else has better idea or experience with this.

 

image.png.bac582bf8a76c7d462ff72ad13423528.png

 

Hi ... thanks. 

 

Are you suggesting that the light loads (back up loads) be placed on the inverter / battery for now (with grid supplementing) and that the larger loads (home load) be connected directly to grid?

 

If I connected the whole house (this is what I mean as whole house) as the back-up load and battery could not handle the load, surely it will switch to grid power to take over?  Is this understanding wrong? ... Ignore a power failure fow now.  If there is a power failure and the battery has insufficient charge, I understand that the system would go down.  In this case, would it trip, or just shut down?

 

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  • 3 weeks later...
On 2021/08/11 at 7:18 PM, JayN said:

I want to install a starter system which I can build on with time.  My home has a 3 phase supply (no idea why), as my power consumption is only around 900kWH per month.

900kWh per month is huge. I averaged over years about 300kWh/month in a 2 person household. Of course it depends on the number of persons in the household.

The most important consideration is the size of the battery and also the most costly one. It depends on how long your system shall survive on load shedding or other blackout. Sum it up in kWh and consider it might happen when the batteries are down to 20% SOC. You average about 30kWh per day or 1.25kWh each hour. If you want to survive 2.5 hours load shedding you need 3.125 kWh from the batteries at 20% SOC. That means your Batteries should have at least 15.6 kWh capacity.

Consider also to install solar heating panels for the geysers. I recommend at least one m² per person in the household. That could reduce your electricity consumption and with this the need of battery capacity.

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My consumption is 900kWh/month. On a 5kW inverter with 6kWpv I generate about 23kWh/day average over a year in JHB.

I'm not sure what the price difference between a single phase 8kW inverter (Sunsync) is vs the 12kW 3 phase, but I imagine the difference might pay for you to convert to a single phase...Just a thought, although you seem to be dead against that.

With a single-phase and separation of your load into essential & non-essential, the 1 battery will suffice in the short term.

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On 2021/08/12 at 1:54 PM, JayN said:

Hi ... thanks. 

 

Are you suggesting that the light loads (back up loads) be placed on the inverter / battery for now (with grid supplementing) and that the larger loads (home load) be connected directly to grid?

 

If I connected the whole house (this is what I mean as whole house) as the back-up load and battery could not handle the load, surely it will switch to grid power to take over?  Is this understanding wrong? ... Ignore a power failure fow now.  If there is a power failure and the battery has insufficient charge, I understand that the system would go down.  In this case, would it trip, or just shut down?

 

If you want to ignore the effects of a power failure then you might as well not install any batteries and just install more panels, this will get you more savings on electricity quicker. Start your install off the right way, only connect loads to the inverter that your batteries can supply. Install a 40 amp battery fuse so that the fuse will blow instead of voiding your battery waranty. As you add more batteries upgrade the fuse and put on more loads on the inverter. Use battery cable thick enough that it can carry the full 12kw load eventually.

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All good suggestions ...

900kwh/month is normal.  I have two geysers (on timers) and a pool pump.  These three appliances alone consume 500kwh/month.

I am going to go with the 12kw 3 Phase Sunsynk, a hubble AM2 and 8 x 540w panels to start.  I will add on from there ... 1 or 2 more batteries and up to 8 x additional panels.  This will not meet my full need at the moment, but it will reduce my bill for now.

For loadsheeping, I will have to be smart about it and make sure the geysers are off during load shedding.  That will last us the 2-3 hours of load shedding.  With more batteries, I don't have to carefully manage the system.  

 

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On 2021/08/12 at 8:30 AM, JayN said:

I don't really want to make change in respect of the 3 phases.

I have not worked with the thee phase Sunsynk, but if I had the option to do three phase I would start by fitting a three phase changeover and splitting each phase at the DB board to Non-essential and Essential loads and wire only the absolute important things for each phase like lights, alarm system, cctv, gate/garage motors, plugs for fridge, TV and computers to essential. The one battery should give some backup at night during load shedding as long as you stay within the battery limits. 

During day time the excess PV can still feed those non-essentials and let you save a bit on power. 

As your system gro you just swing more loads to essential side.

 

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