diy solar

diy solar

Safe Grid Use of the 5000ES and transformer

Cheap 4-life said:
So then there’s basically ground loops all over the place? Yeah I remember now, Ground wires going up the poles. So from those ground wires that go into the ground and then the ground rod at the house creating a ground loop thru the ground?
Click to expand...
A grounding grid.
It will only carry current, when there is a fault.
Which gives it multiple paths, back to the source.
Which trips the OCD (over current device).
 
Thoughts?
I have 3 5000esus inverters. Running two of them in parallel connected to the grid to cover my 240 loads and charging my battery Bank of 6 48v 100 amp batteries. I will have 18 235W panels on each of these inverters.
I will then have 1 inverter connected the grid running through 5k isolation Transformer running all of my 120 loads utilizing 18 235w panels
Of course I will be finding this isolation Transformer used as the price would not be feasible otherwise. This seems to be the only way I can do this safely while utilizing the grid. Of course just when I think I have it figured out LOL............ Timselectric
 
Shannonsman229 said:
Thoughts?
I have 3 5000esus inverters. Running two of them in parallel connected to the grid to cover my 240 loads and charging my battery Bank of 6 48v 100 amp batteries. I will have 18 235W panels on each of these inverters.
I will then have 1 inverter connected the grid running through 5k isolation Transformer running all of my 120 loads utilizing 18 235w panels
Of course I will be finding this isolation Transformer used as the price would not be feasible otherwise. This seems to be the only way I can do this safely while utilizing the grid. Of course just when I think I have it figured out LOL............ Timselectric
Click to expand...
This will work.
One thing to know is that this makes the 240v inverted system, an ungrounded system.
Nothing wrong with this, but I always add a ground detection system to ungrounded systems. As an early warning. So that I can correct any faults, before they become a problem.
(I just build my own, with a couple of ice cube relays and a red light)
 
Greetings and thanks to all that has helped me!

I was going the return the 5000ES and get a 6kw split phase unit, but how can I be sure the 6kw unit disconnects its transformer (internally) when going into bypass mode? I looked at the manual at it doesn't say on way or another. So, I think I'll explore the route of "never hook the inverter to the grid" . So here is what I'm thinking...

1) place contactors on the AC input of the inverter and AC output of the autotransformer. If the AC output contactor is engaged, then the AC input contractor is disabled, thus inverter can no longer go into a bypass mode, yet allow to charge the batteries if needed.
3) the 5000es has a beefy battery charger 80amp, if the batteries get real low, switch to grid (that enables the AC in for the inverter by disabling the AC output contactor), Once the batteries are charged, switch off grid disconnecting the AC input
4) Obtain another battery charger (smaller) that could be used to top the batteries off and prevent the need to switch to grid most of the time. Configure it to only be enabled if the AC input contactor is off, thus only one charger can be enabled concurrently.
5) Being a microcontroller nut, I'll build something that monitors the inverters call for generator (which likely means bypass mode) and disable the AC output contactor (and allow me to control it over wifi ). The input to transfer switches trigger are also available so I can control them as well, allowing me to choose the input source for the 3 load panels.

Does this seem reasonable? Any tweaks?
 
ajccmc said:
Greetings and thanks to all that has helped me!

I was going the return the 5000ES and get a 6kw split phase unit, but how can I be sure the 6kw unit disconnects its transformer (internally) when going into bypass mode? I looked at the manual at it doesn't say on way or another. So, I think I'll explore the route of "never hook the inverter to the grid" . So here is what I'm thinking...

1) place contactors on the AC input of the inverter and AC output of the autotransformer. If the AC output contactor is engaged, then the AC input contractor is disabled, thus inverter can no longer go into a bypass mode, yet allow to charge the batteries if needed.
3) the 5000es has a beefy battery charger 80amp, if the batteries get real low, switch to grid (that enables the AC in for the inverter by disabling the AC output contactor), Once the batteries are charged, switch off grid disconnecting the AC input
4) Obtain another battery charger (smaller) that could be used to top the batteries off and prevent the need to switch to grid most of the time. Configure it to only be enabled if the AC input contactor is off, thus only one charger can be enabled concurrently.
5) Being a microcontroller nut, I'll build something that monitors the inverters call for generator (which likely means bypass mode) and disable the AC output contactor (and allow me to control it over wifi ). The input to transfer switches trigger are also available so I can control them as well, allowing me to choose the input source for the 3 load panels.

Does this seem reasonable? Any tweaks?
Click to expand...
This works.
The only downside is no power to the house, when charging from the inverter. If that's acceptable, then you are good.
 
Cheap 4-life said:
Then unless the inverters/batteries are sized to cover all of the load on the inverters load panel, the AC input from the grid would have to be connected to the inverter. And to be clearer, above I’m meaning the ability for the inverter to supply power to the inverters load panel at the same time the grid is supplying power to that same load panel
Click to expand...
I believe for the Growatt (and someone correct me if I am wrong) that while the inverter is powering the loads (from battery/solar) and if more load power is needed, the grid is simply supplying DC via the internal DC charging mechanism to the inverter. I think it works this way up to the inverters maximum output.

If the load is greater than the inverters output, then a relay switches into bypass to allow the grid straight to the loads, and at that point the inverter is then doing nothing, it would not be paralleled to the bypass.

I saw an earlier post that showed some other charger/inverter units may have grid following inverters that parallel the grids power, they may also have internal CT's that prevent power from going back to the grid, but I do not believe this is in the Growatt.

So if this is the way its works for the Growatt then the inverter needed would have to be sized greater than your loads to be operational, the solar and battery could be less. Or you would be ok with grid bypass with no help from the inverter during high load times.
 
timselectric said:
This will work.
One thing to know is that this makes the 240v inverted system, an ungrounded system.
Nothing wrong with this, but I always add a ground detection system to ungrounded systems. As an early warning. So that I can correct any faults, before they become a problem.
(I just build my own, with a couple of ice cube relays and a red light)
Click to expand...
Awesome!
 
Thanks again. I have auto transfer switches in place, so if the inverter output is gone, it falls back to the grid. So if the batteries are so low they need the 80amp growatt charge, and it would be going to bypass mode... my transfer switches move the load back to the grid. So it should be pretty automatic. If it falls back too often, its a sign I have under configured the solar side... or not enough sunlight reaches the panels!

Btw, if the inverter firmware was updated to allow disabling AC bypass while allowing the 80amp charger to be used...I think that would resolve this whole problem. Maybe something to raise with the supplier...
 
mhanna said:
I believe for the Growatt (and someone correct me if I am wrong) that while the inverter is powering the loads (from battery/solar) and if more load power is needed, the grid is simply supplying DC via the internal DC charging mechanism to the inverter. I think it works this way up to the inverters maximum output.
Click to expand...
No
The only way that they provide grid power, is through the bypass relay. And ac charging can also only be done, when bypass relay is on.
 
ajccmc said:
Thanks again. I have auto transfer switches in place, so if the inverter output is gone, it falls back to the grid. So if the batteries are so low they need the 80amp growatt charge, and it would be going to bypass mode... my transfer switches move the load back to the grid. So it should be pretty automatic. If it falls back too often, its a sign I have under configured the solar side... or not enough sunlight reaches the panels!

Btw, if the inverter firmware was updated to allow disabling AC bypass while allowing the 80amp charger to be used...I think that would resolve this whole problem. Maybe something to raise with the supplier...
Click to expand...
If the inverter is connected to the grid, it will never lose output. Not sure if I understand your plan.
 
timselectric said:
No
The only way that they provide grid power, is through the bypass relay. And ac charging can also only be done, when bypass relay is on.
Click to expand...
So your saying the growatt cannot provide grid power and solar/battery power to the same loads at the same time?
 
timselectric said:
If the inverter is connected to the grid, it will never lose output. Not sure if I understand your plan.
Click to expand...
I continue to refine this, I won't detail what I was thinking, lol. My plan now to get 2 contactors one for the AC IN and one for autotransformer output side. They will be hooked such if one is on, the other is off. Thus if power is on to the inverter, the autotransformer is disconnected..and visa versa. Maybe a manual switch to control them to start with. But I'd like to explore the inverters dry contact switch but per the specs it looks worthless as "batteries are charged" and "output power from utility" have the dry contact switch results. If that is truly the case, then I'll need to monitor the batteries voltage external, pick the points to go "charge mode" and "invert mode". I'm also thinking the standby mode of the inverter might be of some help in that if the autotransformer is disconnected, then the inverter might shift to standby mode until engaged again. Question; is the protocol the batteries speak on the RS485 ports documented? I'm guessing the battery voltage might be found there.
 
ajccmc said:
I continue to refine this, I won't detail what I was thinking, lol. My plan now to get 2 contactors one for the AC IN and one for autotransformer output side. They will be hooked such if one is on, the other is off. Thus if power is on to the inverter, the autotransformer is disconnected..and visa versa. Maybe a manual switch to control them to start with. But I'd like to explore the inverters dry contact switch but per the specs it looks worthless as "batteries are charged" and "output power from utility" have the dry contact switch results. If that is truly the case, then I'll need to monitor the batteries voltage external, pick the points to go "charge mode" and "invert mode". I'm also thinking the standby mode of the inverter might be of some help in that if the autotransformer is disconnected, then the inverter might shift to standby mode until engaged again. Question; is the protocol the batteries speak on the RS485 ports documented? I'm guessing the battery voltage might be found there.
Click to expand...
The inverter doesn't even know that the auto transformer exists.
Two synchronized transfer switches/ or relays.
Is the best option, you have said.
 
timselectric said:
It can provide both solar and grid, at the same time.
But, only does so through the bypass relay.
Click to expand...
I thought the bypass relay activates when the inverter can’t handle the load or the batteries are depleted
 
The bypass relay is what connects the AC input to the AC output. If setting #1 is set to SUB, the inverter also powers the loads simultaneously.
 
Does SUB mean solar then utility then battery? If that’s the case then battery is only used when solar and utility isn’t enough. Utility will always be enough unless there’s a power outage. So battery wouldn’t supply power to the loads at the same time as utility. Or can you adjust the amount of solar/utility/battery to your liking in SUB mode
 
ajccmc said:
Btw, if the inverter firmware was updated to allow disabling AC bypass while allowing the 80amp charger to be used...I think that would resolve this whole problem. Maybe something to raise with the supplier...
Click to expand...
This feature would be great on Off-Grid installations, Back-up generator would only have to be big enough to charge batteries (80A). Instead of powering all loads and charging batteries.
 
LeRoyK said:
Back-up generator would only have to be big enough to charge batteries (80A). Instead of powering all loads and charging batteries.
Click to expand...
I think that is ideal. For occasional ‘big’ loads like a tablesaw you can work that out.
 
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