Questions about an AC coupled powerwall

Photovoltaik.blog

Photovoltaik.blog

New member
Joined
Dec 27, 2017
Messages
16
Hello everyone!

I'm Mark from the south of Germany. I've been reading her for a while and am currently collecting 18650 cells.

image_ihbjco.jpg


And now I have reached a point where I cannot avoid to ask questions myself.

## My current situation ##
I have a 9.9kWp photovoltaic system with a Fronius Symo 8.2-3m inverter.
An air heat pump and the house electrical system are attached to it.

My electricity consumption in February looks like this at the moment:

image_rabohu.jpg


A day looks like this in something:

image_htpuve.jpg


That is about 45kWh per day in winter, for which the heating is mainly responsible.
Unfortunately, I don't have any values from the summer of last year for comparison. However, I assume that I would be self-sufficient during the day and only use electricity at night. Excess electricity is currently being fed into the grid and paid for.

I would therefore like to use the superfluous current to charge a power wall to cover the electricity consumption at night. I think I will need at least 5kWh for this.

## What I need next ##
Which inverter is best suited for my project?
Or is an inverter completely wrong?

I was thinking of the PIP5048MS because it is attractively priced and can be expanded.
The way I figured it, I made a simplified drawing:

image_vdkzsl.jpg


What do you think? What would be the best thing in my situation?

Thank you very much!
 
You're pretty much on point. Yes, the PIP4048 is what I'd recommend over in your area. There are plenty of people on the forums that have one and are loving it. And it's easy to work with and monitor.
Daromer (DIY Tech & Repairs) has several videos on this subject. He's using a contactor to switch between mains and inverter. You could do the same so that at night when you are running off battery, you can switch to mains if need be. You will also need to install a secondary electric panel to do this so that you can control what is on inverter/grid and what is only grid.

Welcome to the forums! :D We don't mind lurkers ;)
 
A few minutes ago I ordered the PIP 5048MS from EASun Power for about 546 (673$). Very cheap, i think. :D

Did I understand that correctly when I say:
"In a secondary electric panel I control which of the three phases are always connected to the grid and which are connected to the battery."
If I'm right, it would be perfect to leave the heating on the grid and hang all other loads on the battery.


Next steps:
- Watching videos from Daromer
- Getting more knowledge in using a contactor

Thanks for the warmwelcome :)
 
Yeah, the first panel (the one already installed) is your main panel that is always mains connected. For obvious reasons. The second panel will go through the contactor switches and you can select which power is feeding that panel, whether it's the mains or the inverter.
The contactors switch so fast that there's much of a disconnect electrically speaking and you may only see the lights dim slightly during the switch over. Daromer can give you specifics on the actions/responses. In his videos he has a scope connected to show what's going on, too.
 
Also note that the PIP have built in ATS so you dont need to use an external device. But if you want the easy way out and be able to work on the solar an external switch is the way to go.

A normal contractor switches in between 5-15ms. Same does the PIP. Note that its important to only switch if the device synchronizes with the grid. The PIP does that if im not mistaken. Otherwise you could create a spike switching to fast.
 
The PIP is not a grid-tie inverter. From your original diagram it seems you're trying to tie it back into the grid. The PIP is an off-grid inverter with a grid backup. It does have a built-in AC charger to charge the batteries through your grid, but I'm not sure if it knows how to only charge when you have excess solar power from your other grid-tie system and then go on battery at night.

Other inverters like SMA Sunny Island may be more suited for your needs. It works with your grid-tie inverter in the sense that if it it senses you're sending excess power back to the grid, it will then kick in the charger to charge the batteries, and at night it can then send power back into the grid to power your house. There's no need to have a secondary panel because it's all grid-tied into your main panel.
 
Korishan said:
Yeah, the first panel (the one already installed) is your main panel that is always mains connected. For obvious reasons. The second panel will go through the contactor switches and you can select which power is feeding that panel, whether it's the mains or the inverter.
The contactors switch so fast that there's much of a disconnect electrically speaking and you may only see the lights dim slightly during the switch over. Daromer can give you specifics on the actions/responses. In his videos he has a scope connected to show what's going on, too.
Click to expand...

I think i got a contactor installed for my Fronius Symo. If I understood correct, i need the same for the PIP 5048MS.

not2bme said:
Other inverters like SMA Sunny Island may be more suited for your needs. It works with your grid-tie inverter in the sense that if it it senses you're sending excess power back to the grid, it will then kick in the charger to charge the batteries, and at night it can then send power back into the grid to power your house. There's no need to have a secondary panel because it's all grid-tied into your main panel.
Click to expand...

This is exactly what I want to archive. So my question is: Can i archive this goal with a PIP 5048MS + contactor or is a SMA Sunny Island the better solution?

I try to cancel the order for now. I have plenty of time for the a solution and I would like to understand the things i do. May I ordered too fast :)

Im very interested in your replies.
Thanks!
 
I'm not too familiar with these ac coupled storage so I can't really offer any more assistance. Here's a few more links on AC coupled storage that may help.

http://www.bougetonile.com/wiring-d...l-2-ac-the-ac-coupled-tesla-powerwall-2-home/

https://www.solarquotes.com.au/blog/powerwall-2-warranty/

https://mcelectrical.com.au/blog/sunny-boy-storage-review/

I just know that any commercial solution is quite expensive. A sunnyboy usually runs in the $3kusd. Not worth the investment for just a partial return. Most of us here are DC coupled, with a few that have both ac (grid-tie) and dc coupled (off-grid) on a separate system with two sets of panels. Others here have a hybrid system where the inverter is capable of battery storage. So the panels come into this hybrid inverter where the batteries are also attached to it. This hybrid will then charge the battery and send it to the grid the excess. You will need to completely replace your Fronius in this case.

For the PIP, it's not a grid-tie device but off-grid. So a seperate sub panel is a must. If you can figure out how to charge through some external programming, then maybe it's possible. So if you're willing to get your hands dirty, and have a current sensor at the panel hooked up to a raspbery pi and then have the pi control the state of the pip, to be on charging mode and battery mode, etc.

Even if you get the Hybrid version of the PIP, which is a grid-tie hybrid that allows you to tie into the grid, you still need some sort of meter to tell the hybrid to switch from charging to battery mode, unless you plan to replace your Fronius with this.
 
No the PIP can not feed the grid. If you do that you get a nice little fire :p


Hybrid MPI version or something else. I use the Hybrid version.
 
After watchingreading and watching videos, i updated the pictures for myself. Just to understand the difference better.
I suggest to watch the following video:
It helped me a lot to understand the diffence between grid-off,grid-tie andhybrid.


image_pjmpif.jpg

image_babqpt.jpg

OFF GRID HYBRID


So i would like to go with the hybrid inverter. That seems to me the best solution.
What do you think? Could the Fronius LOAD MANAGER be a solution in the HYBRID version?


In addition to the SMA Sunny Island, the MPI Hybrid from MPP Solar has already been recommended to me.
Perfect would be aSMASunny Boy Storage, but it doesn't support 48V.

Do you have any more hybrid inverter recommendations for me?
 
Thanks for your recommendation @Jon
TheMultiGrid 3kVAfrom victron energy looks interesting. And there are nice wiring diagrams, better than mine.

This is exactly the setup i would like to go:

image_jcjidk.jpg



The 3kVA brings me to a additionalquestion:
As you can see in my first post, i havetimes where we consume more the 3kVA over a longer period. Especially when my wife is in the kitchen ;)

So will this work with a hybrid inverter with 3kVA like the mentioned above?
Because if not, there seems just on solution --> The MPIHybrid Series with 10kVA from MPP Solar/Voltronic.
 
The Multigrid will loadshare when your demand is greater than the inverter capacity.
You can also add up to 6 in parallel over time as budget allows if you need
 
Photovoltaik.blog said:
Thanks for your recommendation @Jon
TheMultiGrid 3kVAfrom victron energy looks interesting. And there are nice wiring diagrams, better than mine.

This is exactly the setup i would like to go:

image_jcjidk.jpg



The 3kVA brings me to a additionalquestion:
As you can see in my first post, i havetimes where we consume more the 3kVA over a longer period. Especially when my wife is in the kitchen ;)

So will this work with a hybrid inverter with 3kVA like the mentioned above?
Because if not, there seems just on solution --> The MPIHybrid Series with 10kVA from MPP Solar/Voltronic.
Click to expand...

Farends said:
It seems that the solax 2nd generation hybrid will work well to
Click to expand...
You should look further in to the Victron specs. I belive some of them have a boost function, but i dont think, that the 6Kw spike is a problem. It will just get the nessesary power from the grid.
 
I would like to keep you informed :D

My Victron MultiPlus 5000 arrived some weeks ago and i managed to set up my first 1kWh 14s10pbattery.
I learned a lot more than i thought. Awesome!

I thought i can use my S0 energy meter and connect it to the VE Venus, but the Venus only understands ModBus protocol.
So i bought theET340 energy meter from Victron, but missed the RT485 to USB cable ;)

So i still need to wait some days, before i can use my battery.

I also need to install a BMS. I already bought acheapBMS. May there are better BMS for 14s10p batteries.
I need to read more more more ...


image_ncypsr.jpg

image_ttvhht.jpg

image_gbawvz.jpg

image_imnpqz.jpg

image_pcubqn.jpg
 
Good work. Though it looks like your soldering are cold joints many of them. They just look like blobs on the surface of the cells. What soldering iron did you use?

It should look closer to this:
 
You must log in or register to reply here.
Back
Top