wayne530
New Member
- Joined
- Mar 7, 2022
- Messages
- 117
This is the first phase of a solar/battery backup system for our house. This phase does not include any of the solar work (stay tuned for that), but today, after months of planning, ordering parts, lots of waiting, we finally turned the system on and so far (knock on wood) it has been running well!
The system is comprised of the following:
- 2 MPP Solar LV6548 in split-phase configuration
- 6 EG4-LifePower4 (without LCD) 48V 100AH batteries (in an EG4 enclosed battery rack)
- Siemens DTNF322 double throw 3-pole safety switch (used as a transfer switch)
- Siemens subpanel
The transfer switch has two inputs, one from the main panel and the other from the combined inverter output, and the output of course feeds the subpanel. We pulled all the critical ckts (20 in total) up out of the main panel and into a gutter on the opposite side of the wall to be spliced and extended to drop into the subpanel.
Unfortunately, there wasn't enough wall space or clearance on the side of the garage to put the battery cabinet and inverters closer to the main panel as it'd prevent, or at least make very challenging, parking a car on that side of the garage. For better or worse, we also have two sets of windows on that side of the garage. tl;dr we had to put the batteries/inverters on opposite ends of the garage side wall and run some conduit with gutters for:
(1) main panel supply to the inverter for AC battery charging and bypass;
(2) main panel supply to the transfer switch;
(3) inverter output to the transfer switch
Here we also discovered an interesting design "quirk" in the Siemens DTNF322 safety switch detailed here:
diysolarforum.com
On the DC side of things, everything is connected to the EG4 battery cabinet bus bars in a diagonal configuration. The topology was recommended by @smoothJoey in this thread:
diysolarforum.com
I did add Class T fuses anyway and will also add a disconnect/DC breaker so I can disconnect the inverters from the batteries for maintenance. There is still some tidying up (wire management, labels, removing tape, etc) I need to do on the inverter side of things, plus the DC breakers haven't arrived yet, so you can see they're not installed.
Everything is mounted on ~1/2" (it's some weird thickness like 17/32" because that's all we could find) with 1/4" of Hardie backer.
There's no way this project ever would've come together without this forum and huge shoutouts to @smoothJoey @FilterGuy @RichardfromEG4 for answering so many of my questions, especially on the complex topic of Neutral-Ground bonding, which is pretty critical to understand if you plan to approach a similar build with multiple AIO inverters.
In the next phase of the project, we'll be removing an existing solar array that is implemented with microinverters and replacing it with a much larger array of probably around 10kW. Stay tuned for that. In the meantime, if you have any questions, please let me know!
The system is comprised of the following:
- 2 MPP Solar LV6548 in split-phase configuration
- 6 EG4-LifePower4 (without LCD) 48V 100AH batteries (in an EG4 enclosed battery rack)
- Siemens DTNF322 double throw 3-pole safety switch (used as a transfer switch)
- Siemens subpanel
The transfer switch has two inputs, one from the main panel and the other from the combined inverter output, and the output of course feeds the subpanel. We pulled all the critical ckts (20 in total) up out of the main panel and into a gutter on the opposite side of the wall to be spliced and extended to drop into the subpanel.
Unfortunately, there wasn't enough wall space or clearance on the side of the garage to put the battery cabinet and inverters closer to the main panel as it'd prevent, or at least make very challenging, parking a car on that side of the garage. For better or worse, we also have two sets of windows on that side of the garage. tl;dr we had to put the batteries/inverters on opposite ends of the garage side wall and run some conduit with gutters for:
(1) main panel supply to the inverter for AC battery charging and bypass;
(2) main panel supply to the transfer switch;
(3) inverter output to the transfer switch
Here we also discovered an interesting design "quirk" in the Siemens DTNF322 safety switch detailed here:
Siemens DTNF322 manual transfer switch - lever-side knockouts
Hey y'all, so no smoke or anything destroyed to report, but if you are thinking of using a Siemens double-throw safety switch as a manual transfer switch (for example to switch between utility and off-grid inverter power), please be aware that although there are side knockouts on the lever-side...
diysolarforum.com
On the DC side of things, everything is connected to the EG4 battery cabinet bus bars in a diagonal configuration. The topology was recommended by @smoothJoey in this thread:
Class T fuse Size for two LV6548 Controllers - with 4 48v LiFePO4 batteries
Planning on using a Class T fuse, rated at 300a per controller. is this the correct fuse for use with 4 48v LiFePO4 batteries? And will I be able to add two more batteries later with this fuse? Thanks for any help, getting a little confused on this issue. Batteries are "48V 100AH LiFePower4...
diysolarforum.com
I did add Class T fuses anyway and will also add a disconnect/DC breaker so I can disconnect the inverters from the batteries for maintenance. There is still some tidying up (wire management, labels, removing tape, etc) I need to do on the inverter side of things, plus the DC breakers haven't arrived yet, so you can see they're not installed.
Everything is mounted on ~1/2" (it's some weird thickness like 17/32" because that's all we could find) with 1/4" of Hardie backer.
There's no way this project ever would've come together without this forum and huge shoutouts to @smoothJoey @FilterGuy @RichardfromEG4 for answering so many of my questions, especially on the complex topic of Neutral-Ground bonding, which is pretty critical to understand if you plan to approach a similar build with multiple AIO inverters.
In the next phase of the project, we'll be removing an existing solar array that is implemented with microinverters and replacing it with a much larger array of probably around 10kW. Stay tuned for that. In the meantime, if you have any questions, please let me know!
