TN Off Grid Installation

[Banjoman]

All,

Good morning I am looking to get some clarification based on a few items I will lay out below. We are looking into installing a ground mount array at my home in Middle TN with an AIO inverter & battery backup. After some lengthy research and communication with my local power company it seems Grid-Tie is just not something I want to tango with in my area. (See attached documentation that I would have to endure). Based on my lengthy research I believe a diy Off-Grid is the best option. My questions are mainly based on the permitting documentation and passing inspection without grid interconnectivity. Also, what is the best way to wire in the following equipment to meet NEC and local Power Utility code without back feeding the grid.

1. AIO will be EG4 Powerpro ESS w/ 2 batteries
2. Ground Mount Solar array with Canadian Solar CS6W-MBAG-535 Bifacials Qty (35) so total array KW = 18.725
*Estimated wire run to AIO is 300' maximum based on where I have to trench*
3. Snap Rack by APA at 30 Degree Angle per zip 37174
Behind Ground Mount will be reflective white rock surface.

Home is not in a HOA and have plenty of room to put in array due south facing. I have contacted a Solar Permitting company and the Ground Mount will be PE stamped per my regional seismic, wind and IBC related regulations.

All equipment was selected based on current and estimated future KWH usage with an EV in the future. Hoping to be able to draw from the Grid when needed to top off batteries or supplement power but have 0 connection for output to grid. Also, if anyone has a recommendation for an electrician that may be willing to help I'm all ears.

 

[MajicDiver]

My questions are mainly based on the permitting documentation and passing inspection without grid interconnectivity.

1. I see nothing in the documents uploaded that indicate you have to pass any inspection if you will be without grid connectivity - who is telling you that there is any inspection to pass ( if you are doing the work yourself)?

2. The uploaded documents assume you are building a generation “asset” intending to export and get reimbursed for exported power. If your intent is to be zero export and just have the grid there to catch starting surges and load beyond what your system can produce at the time then thats totally unaddressed in your uploads- the “source” in document 3 you uploaded is zero or definitely less than 0.05kW ( any quality properly setup grid tie inverter will keep export less than 50 watts, if it won’t don’t buy it) there are no documents my East Tennessee distributor or county publishes that indicate approval is required to self install a grid tied zero export system.

 

[Banjoman]

MajicDiver, thank you for the insight. I thought based on the documents that I do not need a permit but just wanted to be doubly sure. With being off-grid is it best to have a CL panel with major loads removed from the house main and wired directly to CL?

 

[MajicDiver]

Its impossible for someone to say what is best without first knowing the goals and the relative priorities of those goals. I'd suggest starting there, starting out without a plan is inviting mistakes and false starts and miss-spent $. If you have a lot of big electrical loads, I would recommend considering doing something with them before investing in solar, such as installing mini splits to replace traditional central A/C systems, replace electric tank water heaters with tankless propane and use propane for backup heat as opposed to the electric backup heat used in most central heat pump systems.

Based on what I've read in the manuals and on this forum, I am not a fan of the EG4 stuff. I've bought a lot of stuff from/thru Sig Solar, but nothing EG4. My Growatt equipment has been painless to install and get working and no failures whatsoever so far and it works the way its supposed to work and keeps working. My son and I recently went out of town for a week leaving my wife home alone off grid, that's how stable and reliable the equipment has been. She is smart but non-technical former accountant - I left her a simple checklist (Open two breakers and shut one) how to go back on-grid if the off grid system crashed, she didn't need it. I decided early on I did not want the complexity and failure points of the various ATS setups that are available out there.

I suggest thinking about issues like equipment redundancy, how much time you will spend away from the system and will others be there when your gone when laying out your system. Also, when you see substantial numbers of posts indicating that a vendor is relatively frequently making firmware changes to address issues and making design changes to correct design issues that were foreseeable, avoid those products.

My path was:

1. Installed inverter in basement and grid tied using an abandoned 60 amp feed to my main panel.

2. After couple of months, installed a 100 amp sub panel in basement and used it as a "critical loads" panel powering some stuff in basement. Used 100 amp panel because I wanted to eventually go off grid and use it to feed the main panel. Before considering off-grid, installed four 1-ton mini-splits, obsoleting a 4 ton and 3 ton ancient traditional A/C system. For approximately 18 months was primarily grid tied, went off grid occasionally for testing purposes.

3. Eventually got enough battery and PV capacity to consider taking whole house off grid. Whole house draw is about 42 amps after mini-split installs with everything on, which should never happen.

4. For redundancy, installed another identical inverter with batteries. Can run off grid with either inverter. Typically have one grid tied to the other.

 

[Banjoman]

Its impossible for someone to say what is best without first knowing the goals and the relative priorities of those goals. I'd suggest starting there, starting out without a plan is inviting mistakes and false starts and miss-spent $. If you have a lot of big electrical loads, I would recommend considering doing something with them before investing in solar, such as installing mini splits to replace traditional central A/C systems, replace electric tank water heaters with tankless propane and use propane for backup heat as opposed to the electric backup heat used in most central heat pump systems.

Based on what I've read in the manuals and on this forum, I am not a fan of the EG4 stuff. I've bought a lot of stuff from/thru Sig Solar, but nothing EG4. My Growatt equipment has been painless to install and get working and no failures whatsoever so far and it works the way its supposed to work and keeps working. My son and I recently went out of town for a week leaving my wife home alone off grid, that's how stable and reliable the equipment has been. She is smart but non-technical former accountant - I left her a simple checklist (Open two breakers and shut one) how to go back on-grid if the off grid system crashed, she didn't need it. I decided early on I did not want the complexity and failure points of the various ATS setups that are available out there.

I suggest thinking about issues like equipment redundancy, how much time you will spend away from the system and will others be there when your gone when laying out your system. Also, when you see substantial numbers of posts indicating that a vendor is relatively frequently making firmware changes to address issues and making design changes to correct design issues that were foreseeable, avoid those products.

My path was:

1. Installed inverter in basement and grid tied using an abandoned 60 amp feed to my main panel.

2. After couple of months, installed a 100 amp sub panel in basement and used it as a "critical loads" panel powering some stuff in basement. Used 100 amp panel because I wanted to eventually go off grid and use it to feed the main panel. Before considering off-grid, installed four 1-ton mini-splits, obsoleting a 4 ton and 3 ton ancient traditional A/C system. For approximately 18 months was primarily grid tied, went off grid occasionally for testing purposes.

3. Eventually got enough battery and PV capacity to consider taking whole house off grid. Whole house draw is about 42 amps after mini-split installs with everything on, which should never happen.

4. For redundancy, installed another identical inverter with batteries. Can run off grid with either inverter. Typically have one grid tied to the other.

Our goals are mainly to be more self reliant on our own produced energy and run all major critical loads from the solar system. I have already upgraded to a heat pump hot water heater, new inverter driven heat pump for upstairs and I have a dual fuel package unit running off propane for the bottom floor. Equipment redundancy is a good idea and probably should be explored further.

 

[Banjoman]

Hey guys the other question I have is that could anybody share some simple schematics for the EG4 18kPV to be tied in with an active grid installation but have the EG4 18kPV only act as off-grid with supplemental AC power when there may be too large of loads running for just the 18kPV? Trying to understand options for wiring schematics without back feeding the grid and having to go down the interconnect agreements etc..