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Automatic transfer/changeover switch


LiveBootleg
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I had a decent solar system installed at the end of last year and its been working really well. Only two lines in the original db was configured to stay solely on Eskom power, that being my stove and the other my geyser. The rest of house runs through the inverters and if the batteries are depleted it automatically switches over to Eskom.

I am looking to refine the system a bit as I'd obviously like to have my Eskom usage as low as possible. One improvement opportunity I have is to heat my geyser in the day with PV power as I have a lot of spare capacity there. Currently my geyser (running only on Eskom) has a afternoon cycle to heat the water for the kids to take a bath at night, and another morning cycle before wifey and I take a shower in the morning. 

Now, I had a discussion with the solar installer (he is a qualified electrician) and he recommended installing a changeover switch - this will allow me to supply the geyser with PV power during the day and then with Eskom power at night. Having also jumped on the Home automation bandwagon using Home Assistant with great success across other areas around the house (alarm, lights, pool pump, irrigation etc) I would not want to go back in time and have a manual switch sitting in my db which I need to remember to switch over twice a day. 

I currently have a Smart circuit breaker in my db for the geyser (https://www.robofactory.co.za/home-automation/167-63a-1p-smart-circuit-breaker-with-monitoring-ewelink.html) which allows me to activate the timer in the afternoon and the morning using Home Assistant automations. I also get to switch it on or off using my mobile if there is a need and I also get the benefit of monitoring the power - either in real time or looking at the monthly stats. This works like a charm.

My idea is to add a 2nd smart circuit breaker (same one), which feeds power from the inverter to the geyser and I can configure the afternoon cycle to simply draw power from the 2nd circuit breaker instead of the 1st one. That would swing roughly 50% of power usage on my geyser from Eskom to solar which will save me a bit more which is great.

My challenge though is this: In the rare event where the software lets me down and for some bizarre reason both circuit breakers are turned on at the same time (should not happen, but what if it does?). Logic tells me that this will cause problems - I have very limited understanding of electricity and the implications of this; effectively powering a geyser from both sources at the same time is surely not ideal.

So, how would I prevent this from happening by implementing a failover not using software? A manual failover switch will never allow the power supply from both sources, but how do I add a mechanism to the circuit breaker I have and the one I intend to install to prevent this from happening.

This may not be in the correct thread, but please do advise - would love to hear your thoughts on this.

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  • 11 months later...
On 2021/05/12 at 3:29 PM, LiveBootleg said:

I had a decent solar system installed at the end of last year and its been working really well. Only two lines in the original db was configured to stay solely on Eskom power, that being my stove and the other my geyser. The rest of house runs through the inverters and if the batteries are depleted it automatically switches over to Eskom.

I am looking to refine the system a bit as I'd obviously like to have my Eskom usage as low as possible. One improvement opportunity I have is to heat my geyser in the day with PV power as I have a lot of spare capacity there. Currently my geyser (running only on Eskom) has a afternoon cycle to heat the water for the kids to take a bath at night, and another morning cycle before wifey and I take a shower in the morning. 

Now, I had a discussion with the solar installer (he is a qualified electrician) and he recommended installing a changeover switch - this will allow me to supply the geyser with PV power during the day and then with Eskom power at night. Having also jumped on the Home automation bandwagon using Home Assistant with great success across other areas around the house (alarm, lights, pool pump, irrigation etc) I would not want to go back in time and have a manual switch sitting in my db which I need to remember to switch over twice a day. 

I currently have a Smart circuit breaker in my db for the geyser (https://www.robofactory.co.za/home-automation/167-63a-1p-smart-circuit-breaker-with-monitoring-ewelink.html) which allows me to activate the timer in the afternoon and the morning using Home Assistant automations. I also get to switch it on or off using my mobile if there is a need and I also get the benefit of monitoring the power - either in real time or looking at the monthly stats. This works like a charm.

My idea is to add a 2nd smart circuit breaker (same one), which feeds power from the inverter to the geyser and I can configure the afternoon cycle to simply draw power from the 2nd circuit breaker instead of the 1st one. That would swing roughly 50% of power usage on my geyser from Eskom to solar which will save me a bit more which is great.

My challenge though is this: In the rare event where the software lets me down and for some bizarre reason both circuit breakers are turned on at the same time (should not happen, but what if it does?). Logic tells me that this will cause problems - I have very limited understanding of electricity and the implications of this; effectively powering a geyser from both sources at the same time is surely not ideal.

So, how would I prevent this from happening by implementing a failover not using software? A manual failover switch will never allow the power supply from both sources, but how do I add a mechanism to the circuit breaker I have and the one I intend to install to prevent this from happening.

This may not be in the correct thread, but please do advise - would love to hear your thoughts on this.

Get a change over with a mechanical interlock, only one can be switched on

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Hi - I have the exact same situation, I have a solar system with 18 panels and it works great. I am sitting with huge extra power from the panel which I want to make use of for my geysers. Finally, can you please advise what solution you have employed that works with the solar system and grid together hassle-free to take PV power to the geysers

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Hi - I have the exact same situation, I have a solar system with 18 panels and it works great. I am sitting with huge extra power from the panel which I want to make use of for my geysers. Finally, can you please advise what solution you have employed that works with the solar system and grid together hassle-free to take PV power to the geysers

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I've been looking around for solutions too and came up with too possibilities:

1. A dual geyser element where the second element is designed for DC i.e. it gets power from the solar panels on the DC bus bypassing the inverter. https://www.valsa.co.za/wp-content/uploads/2021/09/PV-Solar-GeyserWISE-Kit-1.pdf

2. A heat-pump which can provide more than 3.5kw of heating power for less than 1kw input. https://itssolar.co.za/product/3-6kw-its-residential-heat-pump/

The advantages of option 1 is cost, about a third of the price of option 2 (R5,500 vs R16,000). Option 2 is worth considering as it's super efficient you could just run it off the inverter without having to worry about a timer to schedule your hot water.

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On 2021/05/12 at 3:29 PM, LiveBootleg said:

I had a decent solar system installed at the end of last year and its been working really well. Only two lines in the original db was configured to stay solely on Eskom power, that being my stove and the other my geyser. The rest of house runs through the inverters and if the batteries are depleted it automatically switches over to Eskom.

I am looking to refine the system a bit as I'd obviously like to have my Eskom usage as low as possible. One improvement opportunity I have is to heat my geyser in the day with PV power as I have a lot of spare capacity there. Currently my geyser (running only on Eskom) has a afternoon cycle to heat the water for the kids to take a bath at night, and another morning cycle before wifey and I take a shower in the morning. 

Now, I had a discussion with the solar installer (he is a qualified electrician) and he recommended installing a changeover switch - this will allow me to supply the geyser with PV power during the day and then with Eskom power at night. Having also jumped on the Home automation bandwagon using Home Assistant with great success across other areas around the house (alarm, lights, pool pump, irrigation etc) I would not want to go back in time and have a manual switch sitting in my db which I need to remember to switch over twice a day. 

I currently have a Smart circuit breaker in my db for the geyser (https://www.robofactory.co.za/home-automation/167-63a-1p-smart-circuit-breaker-with-monitoring-ewelink.html) which allows me to activate the timer in the afternoon and the morning using Home Assistant automations. I also get to switch it on or off using my mobile if there is a need and I also get the benefit of monitoring the power - either in real time or looking at the monthly stats. This works like a charm.

My idea is to add a 2nd smart circuit breaker (same one), which feeds power from the inverter to the geyser and I can configure the afternoon cycle to simply draw power from the 2nd circuit breaker instead of the 1st one. That would swing roughly 50% of power usage on my geyser from Eskom to solar which will save me a bit more which is great.

My challenge though is this: In the rare event where the software lets me down and for some bizarre reason both circuit breakers are turned on at the same time (should not happen, but what if it does?). Logic tells me that this will cause problems - I have very limited understanding of electricity and the implications of this; effectively powering a geyser from both sources at the same time is surely not ideal.

So, how would I prevent this from happening by implementing a failover not using software? A manual failover switch will never allow the power supply from both sources, but how do I add a mechanism to the circuit breaker I have and the one I intend to install to prevent this from happening.

This may not be in the correct thread, but please do advise - would love to hear your thoughts on this.

Did you come right? did you find a solution?. Since my issue is similar to what you have explained above, I would like to know if you have finally found a solution that can be employed in my situation- thanks

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ZAR 241.39 | TOMZN Single Phase Din Rail ATS 220V Dual Power Automatic Transfer Electrical Selector Switches Uninterrupted 2P 63A 100A 125A
https://a.aliexpress.com/_vEI5dr

Look for a local equivalent if possible.

This has two inputs, and one output. If one input "fails", it changes to the other. It can also be manually switched. It can NEVER connect both inputs to the output, no matter what you try. 😄

 

Edited by TimCam
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2 hours ago, TimCam said:

ZAR 241.39 | TOMZN Single Phase Din Rail ATS 220V Dual Power Automatic Transfer Electrical Selector Switches Uninterrupted 2P 63A 100A 125A
https://a.aliexpress.com/_vEI5dr

Look for a local equivalent if possible.

https://e-glow.co.za/products/ats-toq5-63a-ac-2p-230vac-tomzn

I have bought from this guy, quick delivery and he has the solar version available too.
He has stock in SA so no waiting or hassles with import.
I use this to bring my non-essential loads to the essential side on loadashedding.
Works great and never misses a beat.

Edited by WannabeSolarSparky
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Would something like this work? 

https://www.liteglo.co.za/shop/onesto-mc2-20-22943-4-pole-20amp-230v-2xno2xnc-contactor/#

 

It's a contactor that has 2 NO + 2NC. There are 40amp versions as well. My thinking is that eskom gets connected to the NC terminals and the inverter to NO. When you want to switch from eskom to inverter, just apply power to the coil. The eskom circuit is now broken and the inverter side complete. You can control this device with something like a CBI Astute making it wireless. 

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3 hours ago, Rid00 said:

Would something like this work? 

https://www.liteglo.co.za/shop/onesto-mc2-20-22943-4-pole-20amp-230v-2xno2xnc-contactor/#

 

It's a contactor that has 2 NO + 2NC. There are 40amp versions as well. My thinking is that eskom gets connected to the NC terminals and the inverter to NO. When you want to switch from eskom to inverter, just apply power to the coil. The eskom circuit is now broken and the inverter side complete. You can control this device with something like a CBI Astute making it wireless. 

@Rid00the specification for changeover switch   calls for a break before make contact arrangement . Typically relays and contactors is non-conforming unless they specify this.  

The break before make is of utmost importance , otherwise you will have a moment when Escom grid and inverter output meets each other, with devastating results to equipment.  For this reason you must have certified device for this purpose.

Do you specifically need electrical operation for switchover , or is mechanical switch with manual operation ok for you.?

Edited by BritishRacingGreen
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12 minutes ago, BritishRacingGreen said:

@Rid00the specification for changeover switch   calls for a break before make contact arrangement . Typically relays and contactors is non-conforming unless they specify this.  

The break before make is of utmost importance , otherwise you will have a moment when Escom grid and inverter output meets each other, with devastating results to equipment.  For this reason you must have certified device for this purpose.

Do you specifically need electrical operation for switchover , or is mechanical switch with manual operation ok for you.?

While I am aware that many members do not approve of the ACDC brand changeover switch , I use the 40A version of this make for geyser energy manual arbitration , and to me it works safely and elegantly , needs a bit of force to operate in relation to a circuit breaker. It has all certification / quality assurance  and compliance documentation . It works for me.

 

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On 2021/05/12 at 3:29 PM, LiveBootleg said:

I had a decent solar system installed at the end of last year and its been working really well. Only two lines in the original db was configured to stay solely on Eskom power, that being my stove and the other my geyser. The rest of house runs through the inverters and if the batteries are depleted it automatically switches over to Eskom.

I am looking to refine the system a bit as I'd obviously like to have my Eskom usage as low as possible. One improvement opportunity I have is to heat my geyser in the day with PV power as I have a lot of spare capacity there. Currently my geyser (running only on Eskom) has a afternoon cycle to heat the water for the kids to take a bath at night, and another morning cycle before wifey and I take a shower in the morning. 

Now, I had a discussion with the solar installer (he is a qualified electrician) and he recommended installing a changeover switch - this will allow me to supply the geyser with PV power during the day and then with Eskom power at night. Having also jumped on the Home automation bandwagon using Home Assistant with great success across other areas around the house (alarm, lights, pool pump, irrigation etc) I would not want to go back in time and have a manual switch sitting in my db which I need to remember to switch over twice a day. 

I currently have a Smart circuit breaker in my db for the geyser (https://www.robofactory.co.za/home-automation/167-63a-1p-smart-circuit-breaker-with-monitoring-ewelink.html) which allows me to activate the timer in the afternoon and the morning using Home Assistant automations. I also get to switch it on or off using my mobile if there is a need and I also get the benefit of monitoring the power - either in real time or looking at the monthly stats. This works like a charm.

My idea is to add a 2nd smart circuit breaker (same one), which feeds power from the inverter to the geyser and I can configure the afternoon cycle to simply draw power from the 2nd circuit breaker instead of the 1st one. That would swing roughly 50% of power usage on my geyser from Eskom to solar which will save me a bit more which is great.

My challenge though is this: In the rare event where the software lets me down and for some bizarre reason both circuit breakers are turned on at the same time (should not happen, but what if it does?). Logic tells me that this will cause problems - I have very limited understanding of electricity and the implications of this; effectively powering a geyser from both sources at the same time is surely not ideal.

So, how would I prevent this from happening by implementing a failover not using software? A manual failover switch will never allow the power supply from both sources, but how do I add a mechanism to the circuit breaker I have and the one I intend to install to prevent this from happening.

This may not be in the correct thread, but please do advise - would love to hear your thoughts on this.

Hi

What is the details of your decent system, I see your last post you installed 2 x 5kw Growwatts in parallel is my assessment correct?

* If correct then you can run both your geyser and stove thru them. A changeover will be to bypass them to eskom for inverter servicing.

* Splitting of DB was not necessary unless you're planning to use more than 10kw per hour at some point _ 

* My system is a 5kw deye connected to 2 x 3.5kwh pylontech and 12 x 400w Jinko panels. I did not split db I run everything thru deye from march 2021. My wife sometimes overloads the inverter by cooking same time as my geyser on time or turns on all 4 stove plates. She adopted her behavior _ 3 plates doesn't overload 5kw deye (the inverter can easily a 7kw load without overloading 🙂

 

 

 

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