Jump to content

Inverter Technical Questions


Recommended Posts

Hi

I have moved to the Philippines and there are some inverter features that I do not recognise when I lived in the uk. Any help appreciated.

1.  Limiter & Clamp.  I understand that here (and some other countries) if you send power back to the grid they charge you for it.  So inverters have this Limiter with a clamp that makes sure no power is backed to the grid.  But.. Surely, if all power to the house comes through the inverter, grid and solar, and the inverter is set to not export, then you dont need any limiter clamp set up right?  The inverter would only be taking power from the grid when there is not enough solar to meet the house demand.  Am I wrong?

2.  Smart Loads.  Some inverters (Deye etc) have a smart loads function, where if grid power goes out the battery only supplies loads in the smart load circuit.  This is to protect the battery and make it last longer.  essential loads only.  But it means moving loads from the main circuit breaker box to a new box, assuming you can isolate the required loads.  Seems like a big faff (English for annoying waste of time).  isnt this what system sizing, circuit breakers and battery settings are for?  

Thanks in advance,

 

Link to comment
Share on other sites

Posted (edited)
  1. I assume the Clamp/Limiter you are talking about would be the CT Coil. The CT Coil is required to help the inverter decide how to manage the flow of electricty. It helps alot when you direct solar generated electricty to your non-essentials (The load that is not powered by the battery). I recommended it even if an installation is working as a UPS system without solar because it allows the inverter to measure the usage on your incoming supply from the main utility. When you buy a Sunsynk it comes with one and I propose you always install it.
  2. As far as I know it is proposed via the SANS standards in South Africa to have different circuits in separate DB Boards. I assume that would be why the guys here are used to having that. It also makes sense to separate it for manageability and logically for a non-electrically minded person to visually discern the separation. While it may cause extra effort during installation it does make sense do do so. I have done two installations for personal use and I separated everything based on the circuits and also based on where the supply is from. I did have one exception and you can check that via this post: Can I have breakers in an Essentials DB that does not share the Essentials DB Neutral?. On one of my installations I ended with 4x DB Boards on one side of the house and the one I talked about in the above link, on the other side of the house.

When I started on my Inverter and Battery journey I was more concerened with doing it cheaply but fortunately I always do research first and found it better to do it properly even though it costs more. We saved for a long time before we could afford a proper 5K Inverter and a proper 5K LifePO Battery. I did the installation myself and saved that way but acquiring all the required additionals still made it expensive but I steered away from cutting corners and I am glad I did. Doing it by the book and keeping possible future expansion in mind will save you headaches in the future. I know; budget always determine what can be done but rather save for a while and try to do it that way.

I assume the more experienced guys on this forum will give a better understanding.

Edited by TheMac
Link to comment
Share on other sites

1 hour ago, TheMac said:
  1. I assume the Clamp/Limiter you are talking about would be the CT Coil. The CT Coil is required to help the inverter decide how to manage the flow of electricty. It helps alot when you direct solar generated electricty to your non-essentials (The load that is not powered by the battery). I recommended it even if an installation is working as a UPS system without solar because it allows the inverter to measure the usage on your incoming supply from the main utility. When you buy a Sunsynk it comes with one and I propose you always install it.
  2. As far as I know it is proposed via the SANS standards in South Africa to have different circuits in separate DB Boards. I assume that would be why the guys here are used to having that. It also makes sense to separate it for manageability and logically for a non-electrically minded person to visually discern the separation. While it may cause extra effort during installation it does make sense do do so. I have done two installations for personal use and I separated everything based on the circuits and also based on where the supply is from. I did have one exception and you can check that via this post: Can I have breakers in an Essentials DB that does not share the Essentials DB Neutral?. On one of my installations I ended with 4x DB Boards on one side of the house and the one I talked about in the above link, on the other side of the house.

When I started on my Inverter and Battery journey I was more concerened with doing it cheaply but fortunately I always do research first and found it better to do it properly even though it costs more. We saved for a long time before we could afford a proper 5K Inverter and a proper 5K LifePO Battery. I did the installation myself and saved that way but acquiring all the required additionals still made it expensive but I steered away from cutting corners and I am glad I did. Doing it by the book and keeping possible future expansion in mind will save you headaches in the future. I know; budget always determine what can be done but rather save for a while and try to do it that way.

I assume the more experienced guys on this forum will give a better understanding.

Thanks for your reply, appreciated.  I never cut corners, but I also don't like going the long way round if its not necessary.  Smart Loads and CT clamps are not a thing in the UK, or America, or most of Europe, as far as I know. This is why I question them.  The nearest thing to the CT issue is making sure if the grid goes down it isnt still live because of your solar (so workers do not get electrocuted, but that is a slightly different issue).  Do you see any problem with the logic of my counter argument for CT clamps.  Or I should say an alternative installation to avoid needing them?

Link to comment
Share on other sites

19 minutes ago, Slowbutsure said:

Thanks for your reply, appreciated.  I never cut corners, but I also don't like going the long way round if its not necessary.  Smart Loads and CT clamps are not a thing in the UK, or America, or most of Europe, as far as I know. This is why I question them.  The nearest thing to the CT issue is making sure if the grid goes down it isnt still live because of your solar (so workers do not get electrocuted, but that is a slightly different issue).  Do you see any problem with the logic of my counter argument for CT clamps.  Or I should say an alternative installation to avoid needing them?

The ct coil have to be installed with inverters designed to work with ct coils it has nothing to do with the grid configuration in diffrent countries.The Deye,Sunsynk,Solis to name a few is a Hybrid Parity inverter and it needs the ct coil to do blending of available energy resources. The ct looks at utility import and export for the inverters to function as a parity inverter.

25 minutes ago, Slowbutsure said:

The nearest thing to the CT issue is making sure if the grid goes down it isnt still live because of your solar (so workers do not get electrocuted

Most inverters sold will have the function to isolate the inverter from utility when islanding via either SDU(single disconnect unit) or DDU(double disconnect unit)

Link to comment
Share on other sites

6 minutes ago, TaliaB said:

The ct coil have to be installed with inverters designed to work with ct coils it has nothing to do with the grid configuration in diffrent countries.The Deye,Sunsynk,Solis to name a few is a Hybrid Parity inverter and it needs the ct coil to do blending of available energy resources. The ct looks at utility import and export for the inverters to function as a parity inverter.

Most inverters sold will have the function to isolate the inverter from utility when islanding via either SDU(single disconnect unit) or DDU(double disconnect unit)

So What is the benefit of having an inverter with a CT clamp verses one that does not?  Or is there no benefit, just different ways of doing things?

All inverters (hybrid) have the ability to blend grid and solar power, thats the whole point of being hybrid right?  Not sure what your point is.  And those without external CT clamps have internal limiters that are operated through the software.  Im just trying to understand why choose one rather than the other.

 

Link to comment
Share on other sites

14 minutes ago, Slowbutsure said:

So What is the benefit of having an inverter with a CT clamp verses one that does not?  Or is there no benefit, just different ways of doing things?

All inverters (hybrid) have the ability to blend grid and solar power, thats the whole point of being hybrid right?  Not sure what your point is.  And those without external CT clamps have internal limiters that are operated through the software.  Im just trying to understand why choose one rather than the other.

 

Primary benefit is to do what's commonly known as zero-export-to-CT. If you put the CT clamp on the mains breaker, you can set the inverter to do local-export where instead of feeding back to the grid, you feed back just to your own non-essential loads (ie, the loads that are not backed up by the inverter) - treating your house as a local grid, so to speak. A geyser or stove is an example of a high-power item that might not be on the UPS/backed-up circuit (so if the power fails, the geyser/stove won't be run from the inverter), but while the grid is available, the inverter can feed-back excess solar (or even battery) so that these expensive-to-run loads can benefit from excess solar.

Let's assume you have 5kW coming in from your solar array, and your essentials/backup-up loads are consuming 2kW. The balance (3kW) can now go to your non-essentials; essentially the Grid input gets treated as both an Input and an Output, but the Output is limited to your own home. So whilst those high-power loads can't go directly onto the backed-up portion of the inverter (because they'd potentially overload the inverter), they can still be powered by solar when available. There's a fortune of electricity to be saved by doing this.

 

3 hours ago, Slowbutsure said:

2.  Smart Loads.  Some inverters (Deye etc) have a smart loads function, where if grid power goes out the battery only supplies loads in the smart load circuit.  This is to protect the battery and make it last longer.  essential loads only.  But it means moving loads from the main circuit breaker box to a new box, assuming you can isolate the required loads.  Seems like a big faff (English for annoying waste of time).  isnt this what system sizing, circuit breakers and battery settings are for? 

Correct, smart loads would have a separate breaker. The idea behind these is that they're backed-up loads ('semi-essentials' so to speak) that only run under certain conditions. In my house, my stove is on my Smart Load port, so we can cook when the power goes out (frequent occurrence in South Africa!), but it only runs if the battery is above 50% (to stop us from depleting the battery without realizing it, since stoves/ovens are high-power devices). If the battery dips below 50%, the remainder of the essentials (lights, wi-fi. etc) stay powered on, but the stove (which runs the risk of putting us in the dark) gets powered off.

 

Link to comment
Share on other sites

1 hour ago, JayMardern said:

Primary benefit is to do what's commonly known as zero-export-to-CT. If you put the CT clamp on the mains breaker, you can set the inverter to do local-export where instead of feeding back to the grid, you feed back just to your own non-essential loads (ie, the loads that are not backed up by the inverter) - treating your house as a local grid, so to speak. A geyser or stove is an example of a high-power item that might not be on the UPS/backed-up circuit (so if the power fails, the geyser/stove won't be run from the inverter), but while the grid is available, the inverter can feed-back excess solar (or even battery) so that these expensive-to-run loads can benefit from excess solar.

Let's assume you have 5kW coming in from your solar array, and your essentials/backup-up loads are consuming 2kW. The balance (3kW) can now go to your non-essentials; essentially the Grid input gets treated as both an Input and an Output, but the Output is limited to your own home. So whilst those high-power loads can't go directly onto the backed-up portion of the inverter (because they'd potentially overload the inverter), they can still be powered by solar when available. There's a fortune of electricity to be saved by doing this.

 

Correct, smart loads would have a separate breaker. The idea behind these is that they're backed-up loads ('semi-essentials' so to speak) that only run under certain conditions. In my house, my stove is on my Smart Load port, so we can cook when the power goes out (frequent occurrence in South Africa!), but it only runs if the battery is above 50% (to stop us from depleting the battery without realizing it, since stoves/ovens are high-power devices). If the battery dips below 50%, the remainder of the essentials (lights, wi-fi. etc) stay powered on, but the stove (which runs the risk of putting us in the dark) gets powered off.

 

 

Thanks, thats the clearest explanation I have seen.  So basically the CT and smart loads seem to work together?  The CT prevents back feeding to the grid and sends power to non-essential loads.  And the smart load feeds essential loads from the battery when there is no grid power?

Link to comment
Share on other sites

Posted (edited)
24 minutes ago, Slowbutsure said:

The CT prevents back feeding to the grid and sends power to non-essential loads. 

Exactly

 

24 minutes ago, Slowbutsure said:

And the smart load feeds essential loads from the battery when there is no grid power?

Yes: think of Smart Load as an extension of your Essentials, separated by a relay (which, as you mention above, does need a separate set of breakers). When the conditions are appropriate (eg, battery level is high enough), the relay is active and Smart Load gets power. When the required conditions are not met, that relay switches off. And yes indeed, the main purpose of Smart Load is to allow you to put high-power items on Smart Load (i.e., to let them run when the grid is not present - sort-of like essentials) without risk of emptying your battery when there's insufficient PV/battery power to sustain those loads.

In my case, Smart Load is set to get power whenever there's grid; and if there's no grid (which means I run the risk of dipping into battery if it's night-time or if the sun isn't shining), it then gets power whenever the battery is above 50%.

 

Edited by JayMardern
Link to comment
Share on other sites

19 minutes ago, JayMardern said:

Exactly

 

Yes: think of Smart Load as an extension of your Essentials, separated by a relay (which, as you mention above, does need a separate set of breakers). When the conditions are appropriate (eg, battery level is high enough), the relay is active and Smart Load gets power. When the required conditions are not met, that relay switches off. And yes indeed, the main purpose of Smart Load is to allow you to put high-power items on Smart Load (i.e., to let them run when the grid is not present - sort-of like essentials) without risk of emptying your battery when there's insufficient PV/battery power to sustain those loads.

In my case, Smart Load is set to get power whenever there's grid; and if there's no grid (which means I run the risk of dipping into battery if it's night-time or if the sun isn't shining), it then gets power whenever the battery is above 50%.

 

Got it thanks.  Im still a bit confused though why there are hybrid inverters with no CT clamp function.  How does it do the same thing?

Link to comment
Share on other sites

9 minutes ago, Slowbutsure said:

Got it thanks.  Im still a bit confused though why there are hybrid inverters with no CT clamp function.  How does it do the same thing?

An inverter without an external CT clamp won't be able to zero-export. They'll still be able to combine power from grid/solar/battery/etc; and there're even some non-external-CT-clamp inverters that can still do Smart Load-type functionality. They just can't export excess power to your non-essentials.

Link to comment
Share on other sites

1 hour ago, Slowbutsure said:

Got it thanks.  Im still a bit confused though why there are hybrid inverters with no CT clamp function.  How does it do the same thing?

Different types of inverters all get sold as "Hybrid" if they can use battery and solar. Not all hybrid inverters are grid-tied inverters that can fully synchronise to the grid and export energy to the utility. Some hybrid inverters are basically off-grid inverters that can draw extra power from their grid inputs. The first type can use a CT clamp to control export power, the second type does not have a use for one.

Link to comment
Share on other sites

20 minutes ago, GreenFields said:

Different types of inverters all get sold as "Hybrid" if they can use battery and solar. Not all hybrid inverters are grid-tied inverters that can fully synchronise to the grid and export energy to the utility. Some hybrid inverters are basically off-grid inverters that can draw extra power from their grid inputs. The first type can use a CT clamp to control export power, the second type does not have a use for one.

 

Ah, this is what I have been thinking but not had confirmed, even by manufacturers (in China).  Awesome, thanks.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...