Confused with three different systems tied into main panel

[derrallg]

I've tried to search through my Solar Power for Dummies and also this forum and several others and haven't been able to answer my question so I thought I'd ask the experts here.

I have settled on three final bids but I'm confused about how the panels are getting connected to my electrical system. My house was built in 1967 and my main panel is 100A and I'm looking at a system that is between 5.6 to 5.9 kW and was told this is too large for what it could handle. All I could see on the breakers was the word Bryant 2100 which I couldn't find out much about and this means I guess that it is not the Zinsco box that others have said would be wise to replace.

One bid was the easiest for me to understand and was the most expensive because of what he planned on doing in which the installer is going to put in a new 125A main panel in and due to the "120% rule" can handle the system.

Another bid was the cheapest and the installer is going to put a tap next to the old main panel. I tried to find if this was good or bad, but all I could find is that some cities don't allow it in their code but I saw that PG&E does permit it when I saw the NEM application.

The last installer wants to ". . . installing a new sub in the garage to fit the solar and the EV breakers for the EV outlet we will install." The garage is on the opposite side of my house from the main panel and I said I eventually wanted to upgrade to a 240 system. I wasn't sure if this is all that was needed, or if there will be more costs later.

Thanks in advance, and I apologize for my ignorance. This is a lot of new information for me to try and understand.

[cebury]

Those can be all three valid ways to implement solar (wiring between your inverter and the main panel/utility), depending on the specifics of your house, size of the target system, and local rules which we cant see or know from here.

Is your question what are these three types theyre listing, like pros/cons?

[derrallg]

Those can be all three valid ways to implement solar (wiring between your inverter and the main panel/utility), depending on the specifics of your house, size of the target system, and local rules which we cant see or know from here.

Is your question what are these three types theyre listing, like pros/cons?

Essentially yes, I didn't know if one way was better than another.

[max2k]

Essentially yes, I didn't know if one way was better than another.

You might (no guarantee) get better response if you reveal your 'big' plans too- for example you mentioned future upgrade of the garage to 240V. Not exactly sure what that means exactly but I'd probably invest in upgrading MSP from 100 to 200A if it comes to that. One of your options of upgrading it to 125A wouldn't really make sense to me: if someone goes into that trouble why not have extra capacity left from the effort?

[Mike90250]

If you are getting an EV, then upgrade the power to 240V and if you need to upgrade the service panel too, it could be a partially deductible part of the solar install requirement.

[derrallg]

You might (no guarantee) get better response if you reveal your 'big' plans too- for example you mentioned future upgrade of the garage to 240V. Not exactly sure what that means exactly but I'd probably invest in upgrading MSP from 100 to 200A if it comes to that. One of your options of upgrading it to 125A wouldn't really make sense to me: if someone goes into that trouble why not have extra capacity left from the effort?

So my system upgrade issues started because I have a sub-panel in my house that is 110A and has the Federal Pacific breakers so I wanted to include that in the install and figured that I could run a 240V line to the garage from that with a new panel. It wasn't until later after several proposals had come in that it became apparent that installing a 5.5 kW-6.0 kW was a larger system than my 100A main service panel could handle. Most of the companies that I've dealt with except for two will not give me a line item detail of what the system entails and of the two that did the one that is going to do the tap said it's included in his bid. The other most recent installer which is willing to give me a line item proposal is Green Power Installers which I contacted after seeing them recommended here, he said that the 125A box would be easier and cheaper than doing the 200A box $2500 vs $3000.

I live in an area of the SF Bay in a 1600 square foot house in which I don't need AC, have energy efficient appliances, have installed CFLs or LEDs and need to charge a Chevy Volt which doesn't have a high draw as it's limited to 3.3 kW and a level 2 16A charger would suffice. I want to install something that make sense for now and would be acceptable for when I sell probably 15 years from now. It seems like with the crazy appreciation of real estate here that having a newer main and definitely a sub-panel will be something to take care of now to get the 30% Fed rebate and now have to worry about when I do sell.

[max2k]

So my system upgrade issues started because I have a sub-panel in my house that is 110A and has the Federal Pacific breakers so I wanted to include that in the install and figured that I could run a 240V line to the garage from that with a new panel. It wasn't until later after several proposals had come in that it became apparent that installing a 5.5 kW-6.0 kW was a larger system than my 100A main service panel could handle. Most of the companies that I've dealt with except for two will not give me a line item detail of what the system entails and of the two that did the one that is going to do the tap said it's included in his bid. The other most recent installer which is willing to give me a line item proposal is Green Power Installers which I contacted after seeing them recommended here, he said that the 125A box would be easier and cheaper than doing the 200A box $2500 vs $3000.

I live in an area of the SF Bay in a 1600 square foot house in which I don't need AC, have energy efficient appliances, have installed CFLs or LEDs and need to charge a Chevy Volt which doesn't have a high draw as it's limited to 3.3 kW and a level 2 16A charger would suffice. I want to install something that make sense for now and would be acceptable for when I sell probably 15 years from now. It seems like with the crazy appreciation of real estate here that having a newer main and definitely a sub-panel will be something to take care of now to get the 30% Fed rebate and now have to worry about when I do sell.

I have very limited exposure to electrical wiring (my house only) so here's what I understood: your house has split phase service with 100A MSP (2 phase wires coming in from utility side with 240V between them). 6kW system would produce 6,000 / 240 = 25A. That would require 25A x1.25 = 31.25A or 40A(?) standard breaker which doesn't fit your 100A panel buss bar even if it can be overloaded to 125A.

few thoughts:
- please get everything in writing, only that matters at the end
- if you get a feeling you've been ran around by sales ppl may be you have. Don't forget- you drive this process, not them. In this light it helps to identify your needs clearly and have clear end goal for the project. Whoever can get you there at acceptable price gets your business, not necessarily the lowest bidder but the most fitting one.
- don't be shy to ask questions and if sales are not willing to clarify jargon to you drop them altogether- you need to understand to the letter what you are buying, not what you 'think' you're buying.
- if you decide to go with upgrade of MSP I'd go with 200A to have a room if I'll need to hook up extra load over next 15 years. Spending another $3000 at that time would be irrational to me.
- decision to upgrade MSP also depends on how loaded your MSP is right now and probability to add extra loads in the future- may be you have 40A room there already so they could downgrade main breaker to say 80A leaving 45A for your solar 40A feed in.

[brucet9]

So my system upgrade issues started because I have a sub-panel in my house that is 110A and has the Federal Pacific breakers so I wanted to include that in the install and figured that I could run a 240V line to the garage from that with a new panel.

RED FLAG!

FPE panel is a house fire waiting to happen. These breakers, even when new, had about 30% out-of-box failure rate, in many tests requiring more than 150% overload to trip, if at all. Even more puzzling is a 110A sub panel behind a 100A service entrance panel; likely from a cheapo remodeling project at some time. Presumably, the breaker feeding that panel is actually 50A or some such? Replace that thing with a Square-D or Bryant load center ASAP even if you were to abandon the PV idea!

Running 240 circuits to the garage from the sub panel would be a trivial problem, assuming that load calculations on the main panel support that much new load. If not, it might be another reason to upgrade the main.

Before you upgrade the panel, check with PG&E to find out how big a panel your incoming wires from the pole can support. My underground supply from SCE won't support any more than my 100A main panel and would cost thousands of dollars to upgrade due to need to trench to an underground vault in a neighbor's back yard.

The idea to tap in before the panel suggests that your meter is (or could be made so) separate from the panel and therefor the PV connection would not affect the panel's bus bar capacity at all. As long as the requisite automatic disconnect switching is there to prevent back-feeding the Grid in event of an outage, this could be an elegantly simple solution to your undersized panel.

[derrallg]

Thanks brucet9 for the feedback!

RED FLAG!

FPE panel is a house fire waiting to happen. These breakers, even when new, had about 30% out-of-box failure rate, in many tests requiring more than 150% overload to trip, if at all. Even more puzzling is a 110A sub panel behind a 100A service entrance panel; likely from a cheapo remodeling project at some time. Presumably, the breaker feeding that panel is actually 50A or some such? Replace that thing with a Square-D or Bryant load center ASAP even if you were to abandon the PV idea!

Yes, this is one thing I'll be happy to take care of. I know that the previous occupants did a major renovation of the kitchen and put more GFCI plugs then normal according to the inspector and also electrified a shed in the back with a sub-panel to run a heavy duty industrial lathe. I've found Romex coiled up that was live with electrical tape on the end in the rafters of the garage that I want to take care of and a couple of uncovered boxes.

Running 240 circuits to the garage from the sub panel would be a trivial problem, assuming that load calculations on the main panel support that much new load. If not, it might be another reason to upgrade the main.

I decided to upgrade the main so it's done and I don't have to think about capacity for if/when I get a second EV, instant hot water/pump, etc.

Before you upgrade the panel, check with PG&E to find out how big a panel your incoming wires from the pole can support. My underground supply from SCE won't support any more than my 100A main panel and would cost thousands of dollars to upgrade due to need to trench to an underground vault in a neighbor's back yard.

I called the building department at PG&E and he wasn't sure if an upgrade was needed, but the good thing is that everything is above ground and the utility pole is on the edge of my property on the same side as the msp so it's 25 feet away.

The idea to tap in before the panel suggests that your meter is (or could be made so) separate from the panel and therefor the PV connection would not affect the panel's bus bar capacity at all. As long as the requisite automatic disconnect switching is there to prevent back-feeding the Grid in event of an outage, this could be an elegantly simple solution to your undersized panel.

The cheapest quote used this, and I considered it after looking at the discussions online but the house is 50 years old now and I thought "to do it right" I'd go ahead and upgrade the msp.

[don jon]

I have very limited exposure to electrical wiring (my house only) so here's what I understood: your house has split phase service with 100A MSP (2 phase wires coming in from utility side with 240V between them). 6kW system would produce 6,000 / 240 = 25A. That would require 25A x1.25 = 31.25A or 40A(?) standard breaker which doesn't fit your 100A panel buss bar even if it can be overloaded to 125A.

few thoughts:
- please get everything in writing, only that matters at the end
- if you get a feeling you've been ran around by sales ppl may be you have. Don't forget- you drive this process, not them. In this light it helps to identify your needs clearly and have clear end goal for the project. Whoever can get you there at acceptable price gets your business, not necessarily the lowest bidder but the most fitting one.
- don't be shy to ask questions and if sales are not willing to clarify jargon to you drop them altogether- you need to understand to the letter what you are buying, not what you 'think' you're buying.
- if you decide to go with upgrade of MSP I'd go with 200A to have a room if I'll need to hook up extra load over next 15 years. Spending another $3000 at that time would be irrational to me.
- decision to upgrade MSP also depends on how loaded your MSP is right now and probability to add extra loads in the future- may be you have 40A room there already so they could downgrade main breaker to say 80A leaving 45A for your solar 40A feed in.

i know this is old but i have some questions.

My house has an older main panel and the breaker is 100amps. main breaker. wize size 4 gauge from meter.

so im assuming its a 100 bus bar panel.

the system im interested has a Solar Edge system of 5.4kw with 24 amps max rated.

at 24 amps, ill have to go up to 30 amp breaker.

so 100x 1.2=120

120-30=90

will that be ok for me, just downgrading to 90 amps

i have plenty of room for breakers in my panel.

Also, am i calculating the breaker size correctly(30amps) or do i need to add some more for the disconnect etc.

thanks and ill appreciate anyone's help.

[Sunking]

So my system upgrade issues started because I have a sub-panel in my house that is 110A and has the Federal Pacific breakers .

Run away from those panels and breakers as fast as you can. 10's of thousands homes have burnt down using their panels and breakers. To the tune of about 2000 homes a year. They were used in new construction and remodels from 1960 to 1990. To make matters worse they are immune from damages. Go Google

"Federal Pacific Breaker Panel Fires". You will get thousands of hits like this one.

Any EC that would make a bid trying to work around a FP panel should be eliminated. No good electrical contractor would work with a FP panel. They would insist it be replaced, or they would not work with you. Way too much risk and liability for an EC to take on. Only hacks who plan to be gone soon will do it. Real simple, last EC that works on the system gets sued. No good EC will do it.

[macaddict]

One thing to keep in mind, if I understand it correctly, is that if you replace your electrical panel as part of the solar install, you get the 30% ITC of everything. So basically you get a 30% discount on upgrading your electrical panel for future capacity...

[Sunking]

One thing to keep in mind, if I understand it correctly, is that if you replace your electrical panel as part of the solar install, you get the 30% ITC of everything. So basically you get a 30% discount on upgrading your electrical panel for future capacity...

Yep and it comes out of your pocket.

[brucet9]

Yep and it comes out of your pocket.

What does "out of your pocket" mean in macaddict's case?

I will have to re-locate my service panel and would upgrade to 200A PV-ready as part of my up-coming 5.2 kW installation and kitchen remodel that adds several dedicated circuits. I wonder how much of the cost of the new panel, installing a big junction box to splice existing circuits would be allowable under the 30% ITC?

[foo1bar]

so im assuming its a 100 bus bar panel.

It might - it might also be a 125A bus bar.
Find out.

will that be ok for me, just downgrading to 90 amps

Maybe - maybe not.
You'd have to do a load calculation to see if a 90A service is sufficient.
And you'd have to see if your AHJ will allow it.

You may wind up having to install a 125A bus bar panel with a 100A main breaker.
(Or you might want to upgrade to a 200A service and a 225A busbar panel if that's not too expensive to do.)