Final plan review and some questions.

[EnergyIndependentIan]

Hey everyone,

I’m planning my first solar setup and would love your advice to make sure I’m on the right track! Here’s a quick rundown of my plan (still subject to change as I learn more):

Equipment:

• Inverter: 1x EG4 18kPV
• Batteries: 2x EG4 Power Wall Mount (14.3kWh each, total 28.6kWh)
• Solar Panels: 22 Aptos DNA-108-BF10-410W Panels (roof-mounted, no bifacial gain), configured as 2 parallel strings of 11 panels.

What I'm planning around:

• My system’s nominal output is ~45kWh/day (based on 5 peak sun hours).
• My average daily household consumption is ~30kWh/day, with occasional high-demand weeks of ~40kWh/day based off historical data.
• I’m aiming for energy independence most days, but I know weather, shading, and inefficiencies will play a role.

Key Details:

1. Panel Configuration:
   
   • Each panel has a Voc of 37.67V and Isc of 13.11A.
   • 2 parallel strings of 11 panels keep the string voltage at 414.37V, well within the inverter’s 600V limit but high enough that I'm hoping to get some early morning power out of them.
   • The parallel current is ~26.22A, which I know will cause clipping at maximum output but as I understand it the only downside to that is not being able to use all the power the panel is sending when its at max output.
2. Inverter Efficiency:
   
   • Battery-related efficiencies: 99.9% (PV to battery) and 94% (battery to grid/home).
   • Idle consumption: ~70W in normal mode (~1.68kWh/day).
   • For planning I'm assuming ~42kWh/day after losses and the idle use of the inverter.
3. Battery Storage:
   
   • Total capacity: 28.6kWh, which should cover nighttime usage or cloudy days.

Questions:

1. Panel Configuration: Does this setup (2 strings of 11 panels) maximize efficiency, or should I consider a different configuration?
2. Battery Sizing: Is 28.6kWh of storage sufficient for a household with ~30kWh/day usage, or should I consider adding another battery? I have a natural gas generator that I can kick on for emergencies during a power outage so I'm more so asking for general day to day usage where I wont have to get any power from the grid.
3. Panels: Are there better panels for my use case? The panels are what I have been going back and forth between various options on the most.
4. General Advice: Am I missing anything critical in my system design or planning?

Attached is a picture of how I plan on laying out the panels. I know some places require what I've seen referred to as a fire lane on the roof. I've done some digging but I haven't yet been able to find if Mecklenburg County requires that so I know that's something ill have to factor in if they require it.

I plan on doing some of the install myself (installing the panels, batteries, and inverter) and then having someone check over my work. I have an electrician that I've has do all the work on my house so far and who I trust to do a good job but he hasn't worked on many solar projects in the past. I have also reached out to @Supervstech who lives near by who was willing to consult on the project when it comes to the areas my electrician isn't as familiar with.

I'm sure I'm forgetting to add some relevant information but I've been going over my notes long enough and just need to go ahead and post this.

Thanks for your insights! I’m still learning and appreciate any advice or tips you can share.

 

[green mountain boys]

If I understand this correctly, you are going to put all 22 panels on one MPPT input in 2 parallel strings. The 18KPV has 3 trackers. I am not seeing why you would not use 2 trackers to reduce/avoid clipping. You would still have the same string voltage.

 

[EnergyIndependentIan]

You are absolutely right. Not sure why I was fixated on having it on one MPPT. That will definitely be the plan going forward. Thanks!

 

[sumpower]

Battery Sizing: Is 28.6kWh of storage sufficient for a household with ~30kWh/day usage, or should I consider adding another battery? I have a natural gas generator that I can kick on for emergencies during a power outage so I'm more so asking for general day to day usage where I wont have to get any power from the grid.

I would say just stick with your plan, It looks like it has been planned well.
You basically have 19Kw to work with after the sun goes down if you discharge your batteries to 30%.
Most installs don't consume that much overnight.