Okay, this is a common but sometimes tricky situation, especially with adding solar and battery systems. Let's break it down

Understanding Your Existing Setup (E Meter Only)
What it means

"E meter only" means your utility meter is the only disconnect between the utility company and your system. There's no main service disconnect at the meter itself. All the overcurrent protection and distribution is happening downstream in your garage subpanel.

Why this was done

This used to be a common and acceptable practice in many areas, especially for smaller homes or when the main panel was located very close to the meter. It could have been for cost savings or ease of installation at the time.

The Key Question: NEC (National Electrical Code) Compliance

The core issue is whether your existing setup, with the addition of the solar and batteries, meets the current NEC requirements. It's not just about whether it "flies" with your friend's experience; it's about code-compliant safety. Here's what to consider:1. Overcurrent Protection

The NEC is very concerned about the sum of overcurrent devices exceeding the ampacity of the service conductors. This is a common pitfall when adding generation sources like solar and batteries. If the sum of all the overcurrent protection devices exceeds the utility feed rating the service rating needs to be upgraded.2.

Disconnecting Means

The NEC mandates readily accessible disconnecting means for both the service and the solar PV system. These are crucial for emergency responders and service personnel.

Analyzing Your Situation

Let's consider your specific components: 6.72 kW PV System

The output current of this system will depend on the specific inverter model but will be roughly 21A.

Enphase IQ5P Batteries

These batteries can both charge and discharge.

100A Main Breaker in Garage Subpanel

This is the crucial point. This breaker may not provide the protection you need, especially when you add the current from the solar and batteries.

200A Rated Garage Subpanel

The panel rating is important, but the incoming breaker (your 100A main breaker) limits the current it can handle from the utility.

NEC Requirements for Your Configuration (General Guidelines - LOCAL CODE PREVAILS)1. Load Calculation is required to determine the service size. Service Size: NEC requires that the existing utility conductors are sized large enough for the loads that can be applied. If the sum of the existing load and the new loads are more than the existing conductors the service needs to be upgraded.2. Overcurrent Protection and 120% Rule (NEC 705.12(B)(2)(3))This is where it gets technical. You need to carefully calculate the maximum current that can flow through the 100A breaker in your garage subpanel from all sources (utility, solar, and batteries). The NEC (specifically 705.12(B)(2)(3) and similar sections) limits the amount of backfed current (solar + battery) into the service. The basic idea is that the sum of the breaker protecting the service conductors plus the backfed current from the solar and batteries must not exceed 120% of the service conductor ampacity. Example

Let's assume your service conductors are rated for 100A (matching your garage main breaker). The maximum current that can be backfed from the solar and batteries would be: (120% of 100A) - 100A = 20A. If your solar and batteries can potentially backfeed more than 20A, you must upgrade the service conductors and main breaker.

3. Disconnects Main Service Disconnect

The fact that you don't currently have a main disconnect at the meter is a potential issue. Some jurisdictions require a readily accessible disconnect at the meter, especially with the addition of generation. You might need to install a meter main with a breaker.

Solar AC Disconnect

Yes, you almost certainly need a readily accessible AC disconnect for the solar system. This is usually located outside near the point of interconnection.

Battery Disconnect

The Enphase system might have built-in disconnect features, but you need to confirm they meet local codes and provide readily accessible emergency shutoff.

Enphase Combiner

The Enphase Combiner can function as the AC disconnect for the solar if it's located in an accessible location and is properly rated. However, it doesn't typically serve as a main service disconnect.

Answering Your Questions Directly Do they need a new service? Potentially, yes. This depends entirely on the calculations described above and local code requirements. If the backfed current from solar and batteries exceeds the allowable limit, you need a service upgrade (larger conductors, larger main breaker, potentially a new meter main). Do I need to install a solar AC disconnect outside? Almost certainly, yes. This is a standard safety requirement. Would the Enphase Combiner suffice? Potentially, yes, but not as a main service disconnect. It can serve as the required solar AC disconnect if it meets location and accessibility requirements.

Recommendations1. Consult with a Qualified Electrician (One Who Knows Solar)

This is critical. Your friend might be knowledgeable, but they need to be up-to-date on the latest NEC requirements and local codes. Get a professional assessment.2.

Perform a Load Calculation

A proper load calculation is required to determine if the existing service can handle the additional load.3.

Talk to Your Local Building Department/Inspector

They have the final say on what's acceptable in your area. Get their input before you start the installation.4.

Consider a Service Upgrade

Even if it's not strictly required*, upgrading your service might be a good idea for future-proofing and peace of mind.5.

Document Everything

Keep detailed records of all calculations, permits, and inspections.

In Summary

While your existing "E meter only" setup might have been acceptable in the past, adding solar and batteries introduces new complexities. You need to ensure that your system meets current NEC and local code requirements for overcurrent protection, disconnecting means, and conductor sizing. Don't rely solely on anecdotal evidence; get a professional assessment and involve your local building department. A service upgrade might be necessary. Flag for review