Adding Solar and need to ID main panel capacity

Question

There are no complete stickers on the panel, just a partial one that ID’s it as a Hart-Murray. This is a service for two homes, one(ours) has a 90 amp, the other has 100amp. How do I ID the capacity of the main?

Answer 1

Call your power company and ask them what size of service they think you have.

You can also look at the main breaker (first breaker past the meter).

However, on some older panels, there is not one main breaker, but actually up to six. These older panels are a hot mess, and have been outlawed.

You always have, as a "Hail Mary" play, the option to replace your meter pan with a meter-main. This is not possible to DIY but it will establish a main breaker - which solves any safety problems with "Rule of Six" panels. However, of more interest is that many meter-mains are designed with a "solar tap". Thus the solar is able to bypass the main breaker(s), and as such, there is no limit to the size of the solar system other than your service size.

This solar tap can be improvised with any meter simply by splitting the load side of the meter to serve both your original panel and a new panel. However this new panel can serve only solar systems.