Chris's Build Thread

whoinow

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Hey All,
I am designing a system and collecting components as we speak. I am very excited for this project!
Summary:
- 4.725kW of of solar
- Solar Charge Controller
- DC-AC 6kW Inverter
- 31kWh of battery storage using ~1060 Lithium Polymer Spim08hp 3.7v 8ah Flat Pouch Cells LiPo Batteries (75p14s) 48v
- Batrium Watchmon4 with Longmons
- Automatic Transfer Switch between interverter and grid, with batteries/inverter as priority

Rough Diagram:https://drive.google.com/open?id=1FzDuqmHloiIqG_qnkIUK25c-qnPVX4i_
Rough BOM with spec sheets:https://docs.google.com/spreadsheets/d/1LIH_8bZ1c3E2ojVJIu_oWrK34xxhOfi2jU0E5TGOxhg/edit?usp=sharing

Notes:
- This will NOT be a typical grid-tie system, so no back-feeding into the grid. It could change down the road though.
- I am going to be usingbuilding a CANbus to Modbus translatorto turn the charger on/of with the Watchmon and SchneiderComBox.
- Some breakers/fuses might be missing


Parts are trickling in and I working with a solar designer for the PV and an electrician for ATS. More to come!
 

Korishan

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Did you not put this in the Powerwall section on purpose? That is where full builds are expected to go.

What do you mean "not be a typical grid-tie system"? It either is grid-tie, or it isn't.
 

whoinow

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Korishan said:
Did you not put this in the Powerwall section on purpose? That is where full builds are expected to go.

What do you mean "not be a typical grid-tie system"? It either is grid-tie, or it isn't.

Feel free to move it to the correct place.

Well, I thought the definition of grid-tie was feeding into the grid with an inverter from the PV array. Since I am not doing that, and merely switching between power sources, I thought it wasn't technically grid-tie. I guess my definition is wrong per your question?
 

Korishan

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So you're just making a second electrical panel that is fed by the inverter and putting circuits over to that; or using a transfer switch to change power source from inverter or mains.

This is not a grid-tie, just standard installation ;)

Grid-Tie is a special inverter that takes a DC power source and syncs up the AC output with mains and merges the two together in a safe way. When the mains goes down, so does the inverter as it has no source to control the frequency.
However, there are some inverters that can run in standalone mode. I believe the AIMS inverters can do this; but don't quote me on that.

moving thread since this is your build thread ;)
 

whoinow

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Korishan said:
So you're just making a second electrical panel that is fed by the inverter and putting circuits over to that; or using a transfer switch to change power source from inverter or mains.

This is not a grid-tie, just standard installation ;)

Grid-Tie is a special inverter that takes a DC power source and syncs up the AC output with mains and merges the two together in a safe way. When the mains goes down, so does the inverter as it has no source to control the frequency.
However, there are some inverters that can run in standalone mode. I believe the AIMS inverters can do this; but don't quote me on that.

moving thread since this is your build thread ;)

Yea, I will be using at ATS to switch from inverter/mains. I just wasn't sure if this was still called grid-tie since technically I am modifying how the service comes into the main panel. Thanks for the clarification there, it will help with any utility permitting, etc.

The AIMS inverter has an ATS in it, but only rated for 75A at 120V,50A at 240V and I have 100A service. So I am building an ATSwith 100A contactors which will be controlledby the watchmon4.
 

Sean

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I see you intending the ATS to have storage priority - are you expecting to see an energy cost saving eventually ?
 

Korishan

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If you haven't seen these, here's a few videos by Daromer:

 

whoinow

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Sean said:
I see you intending the ATS to have storage priority - are you expecting to see an energy cost saving eventually ?

Yes eventually.

Korishan said:
If you haven't seen these, here's a few videos by Daromer:


I have seen those and incidentally I am using very similar contactors, with interlock. I am not doing any sort of delay though. There will be ~20ms gap between power sources so hopefully the transfer will be make it so devices are not interrupted. I am also using a whole house surge protector to deal with any transients.
 

whoinow

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Sean said:
I see you intending the ATS to have storage priority - are you expecting to see an energy cost saving eventually ?

Sean said:
whoinow said:
Sean said:
I see you intending the ATS to have storage priority - are you expecting to see an energy cost saving eventually ?

Yes eventually.

Timescale ?

I still have to run the numbers. The idea is that will run on grid very minimally and I sized the battery bank to accommodate.
 

daromer

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Note that you always should (need) a delay switching back. If you dont have that you could and will some day end up flickering back and forth when you for instance have an issue. The delay back lets say 60 seconds will save your day and gear!

Thats why most UPSs and inverters that have ATS have that per default. I recommend it for sure :)
 

whoinow

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daromer said:
Note that you always should (need) a delay switching back. If you dont have that you could and will some day end up flickering back and forth when you for instance have an issue. The delay back lets say 60 seconds will save your day and gear!

Thats why most UPSs and inverters that have ATS have that per default. I recommend it for sure :)

I am not sure I follow. Why would it ever flicker back and forth? Also when you say 'back' do you mean back to grid?


I should be clear, the plan is to use the watchmon to control the ATS via the 24vdc coils using one of the relays on the expansion board. So the watchmon will flip the grid/inverter power when any cell is below the LBCO.
 

daromer

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If you have a single source to control the switch it should be fine since batrium have built in delay. The problem is when you introduce a factor without delay or even 2 different factors. Only problem with the batrium is if it fails and doesnt stay stable on one lane. Lets hope that doesnt happen though :) I only run trip shunt on my batrium so it doesnt controll anything back and forth right now.

Lets say you flip back to grid based on low battery and when switching from battery to grid the voltage goes up again and instantly it flickers back to grid again. (Dumb voltage switch with no hysteresis)

OR

If you switch between battery and grid and you have priority grid but the grid is malfunction so it switches back to grid but directly grid fails and switches back to battery.. For instance when there is a short on the grid where i live the grid generally can flicker 3 times in a row within seconds. This is not much but still its something that can destroy gear!
 

Korishan

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If you live anywhere near where there are trees near the lines, you can have fluctuations that cause a rapid switching back and forth between your power inputs. If the normal switching delay is 20ms, then it's possible you could get 10 switches back and forth with a second. That's a lot of extra wear and tear on the contacts/switches.
By using the delay back to grid, you can greatly increase your chances of a successful switch over without disturbing your electrical devices.

If you ever take a UPS and trigger it to battery, then reconnect the AC power, you'll notice it takes it a few seconds to switch back to grid. Even the cheap units do this. Not only is this to protect your equipment, but also the battery and the electronics in the UPS itself. Each time a trigger event occurs, that's a huge hit on the electronics to work to get things to switch over. It's not like 2 railroads merging into 1 and you just switch from one to the other.
 

whoinow

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Thanks guys, I appreciate you spending the time to chat about these things. However, I think I am still missing something. Maybe ATS is the wrong definition for what I am doing.

Basically, I will run on battery as long as I can, until I hit LBCO on any one cell. Then the batrium will flip the contactors to grid via a relay. The contactors I have have 24vdc coils, so it won't be an electrical-mechanical ATS like the one in daromer's videos. There will be no monitoring on the grid, so if the grid is in a poor state, well then that's what I get. The batrium will not flip the contactors to battery again until all cells are at least nominal voltage (or some acceptable level). So I can't see a chance for a flicker here. Am I still missing something? Sorry if I am being dense.
 

daromer

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As i said your setup is not generally prone to issues no. Its ok but beware of that you need a dual system where you disable on 1 and enable on one. You are generally not allowed to just via 1 relay switch source of power.

Ie as in my case 2 contactors is needed where you power either or for getting power through. And switching between them demands that the first one is shut off first. This is where the flickering can happen where you control them one by one. Ie 2 relays not 1. (1 in most countries is not legal unless its installed in some units like inverters or UPS systems)
 

whoinow

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Yea I will being using 2 contactors with a mechanical interlock. I will being using one relay from the watchmon to control the inverter contactor and the grid contactor will be controlled by the NO/NC terminals from he inverter contactor. This way there is only one control for both contactors and they will always be opposite.
 

daromer

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Then you should be fine :) The flickering is when you have more than 1 controller that you have on ATS that is switched via power sources and have priority order
 

daromer

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They are :D I got the 63A version and massive. And the 300A ABB S5N i have for the battery side is also massive. And the sound when it trips :D
 
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