Want to start off by saying I will hire a certified electrician to do all the work. I'm just trying to plan to see what options I have. My electric bill has literally doubled now talking about another 14% increase. I am planning on going with solar, gas is not available. I want to wire the inverters directly into my main 200 A breaker panel so that I can pick and choose what to power. This will be totally off-grid, I'll either have an interlock or transfer switch installed to assure it. I've seen where people backfeed, (don't know if this is the right term) their breaker panel with gas generators usually with 30 or 50 A breakers in their box. Problem is I don't think 50 A is enough to seamlessly power my house. My question is, is it acceptable to backfeed a 100 A's to the box? Obviously using wire rated for 100A.
Posts: 1606 | Location: Ohio | Registered: May 27, 2008
Originally posted by 08 Cayenne: Want to start off by saying I will hire a certified electrician to do all the work. I'm just trying to plan to see what options I have. My electric bill has literally doubled now talking about another 14% increase. I am planning on going with solar, gas is not available. I want to wire the inverters directly into my main 200 A breaker panel so that I can pick and choose what to power. This will be totally off-grid, I'll either have an interlock or transfer switch installed to assure it. I've seen where people backfeed, (don't know if this is the right term) their breaker panel with gas generators usually with 30 or 50 A breakers in their box. Problem is I don't think 50 A is enough to seamlessly power my house. My question is, is it acceptable to backfeed a 100 A's to the box? Obviously using wire rated for 100A.
With all due respect , this is not the place to get the kind of advice you are seeking . The National Electric Code and your AHJ is going to determine what you can and can't do , along with a qualified solar installer .
Posts: 4502 | Location: Down in Louisiana . | Registered: February 27, 2009
Thanks Advice is all I'm looking for, I'm not necessarily going to act on it. Has anyone seen or heard of a 100 A backfeed. Like I said in the first sentence of my post I will get certified people to do the installation. If I cant use 100 A this might not be the direction I take.
Posts: 1606 | Location: Ohio | Registered: May 27, 2008
I've a friend with a cabin in Michigan's north woods with solar. From about November through February the panels don't generate enough power to keep the batteries charged with merely ±100W of load on the system.
"America is at that awkward stage. It's too late to work within the system,,,, but too early to shoot the bastards." -- Claire Wolfe "If we let things terrify us, life will not be worth living." -- Seneca the Younger, Roman Stoic philosopher
I would talk with the solar company and your utility company about a two way meter and selling what you don’t use to the utility company.
“Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.” ― Ronald Reagan
Retired old fart
Posts: 6565 | Location: Near the Beaverdam in VA | Registered: February 13, 2005
Originally posted by 95flhr: I would talk with the solar company and your utility company about a two way meter and selling what you don’t use to the utility company.
That's called Net Metering . Different subject .
Posts: 4502 | Location: Down in Louisiana . | Registered: February 27, 2009
Based on my experience I think the most versatile and cheapest setup is a simple manual 200a transfer switch. You put it between utility power and your 200a panel. At least for my squared panel you can get a 100a interlock. I don't know the code on this and if there are lugs acceptable for 100a in your panel. I found my manual transfer switch for dirt cheap and wiring it is easy. but its big which may be a limitation for your situation.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
With all due respect , this is not the place to get the kind of advice you are seeking . The National Electric Code and your AHJ is going to determine what you can and can't do , along with a qualified solar installer .
This!
Also I see no mention of batteries here. It's a vastly different installation for off grid power or backup power from solar than a standard solar installation. So many factors to consider. I would definitely get batteries though. Solar doesn't work at night and motors have large starting current.
Jesse
Sic Semper Tyrannis
Posts: 21411 | Location: Loudoun County, Virginia | Registered: December 27, 2014
Also I see no mention of batteries here. It's a vastly different installation for off grid power or backup power from solar than a standard solar installation. So many factors to consider. I would definitely get batteries though. Solar doesn't work at night and motors have large starting current.
As someone whose house is powered by offgrid solar, I’ll add that there are a lot of big qualified solar installation companies that do grid-tie solar day in and day out, but know little to nothing about offgrid systems and considerations. I’d ask any potential installer to provide references I could ask about similar systems the installer had done for them.
If the house were not 3,000’ from the nearest utility power the system would have everything it currently does and be tied to the grid as a backup. YMMV, but after providing, being responsible for, and maintaining all utilities to the house and the water and road system for the ranch my mantra has become redundancy. If I had a low cost option for utility power as a backup, I’d have it.
ETA:
quote:
Just call the man.
I’d argue that one needs to go to some effort to educate themselves to make sure they call “the right” man.
Posts: 7379 | Location: Lost, but making time. | Registered: February 23, 2011
It sounds like you are putting your cart in front of your horse. You dont want a manual transfer switch and if electric is your only heat oprion, you dont want to completely disconnect because your bill went up. Ohio is not known as the sunshine state as far as im aware. Start with how much electric you use, what can you cut and how much you will need to generate and store. If you are worried about your electric bill, you will probably have a stroke when you see how much it costs to generate and store your own. Then you can do payoff math and see if it works dor you.
Posts: 3361 | Location: IN | Registered: January 12, 2007
I've done all the math. There will be battery back-up, a lot of it and over 17,000 watts of solar panels. Net metering is not permitted by my electric utility. When I say off-grid I don't mean 100% off-grid for the full year. The system I'm looking at will comfortably run my entire house for 10 months out of the year, at that time I'll be off-grid. The 2 months I need to use electric heat I'll go back on the grid. I was just curious if you can feed 100 A's back to your breaker box instead of the standard 50 A.
Posts: 1606 | Location: Ohio | Registered: May 27, 2008
It took a second to stop and figure out what the hell you're saying and now I can't get the tune out of my head. LOL. shit!
"It did not really matter what we expected from life, but rather what life expected from us. We needed to stop asking about the meaning of life, and instead to think of ourselves as those who were being questioned by life – daily and hourly. Our answer must consist not in talk and meditation, but in right action and in right conduct. Life ultimately means taking the responsibility to find the right answer to its problems and to fulfill the tasks which it constantly sets for each individual." Viktor Frankl, Man's Search for Meaning, 1946.
Posts: 20438 | Location: The Free State of Arizona - Ditat Deus | Registered: March 24, 2011
I was just curious if you can feed 100 A's back to your breaker box
as I said above for my particular box you can buy a 100amp interlok. I suggest you see if there is one for your specific box and what restrictions are placed on it. OTOH I have used both an interlock and a transfer switch and the switch is way, way better and more versatile.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
I would suggest asking this same question to several solar system installers. If they say “No”, my best guess is they are not up to the job or have never seen such a job. Move on to the next company. When someone says “yes” your next question is “Can I speak to those customers?”
I am sure what you seek can be done. I have no idea what it will cost.
As a reference, (in my experience) something in the range of 10KW can be fed through a 50A breaker (our electricians will confirm/dispute this -believe them). The 50A breaker will prevent trying to pull too much from your supply.
Posts: 2172 | Location: south central Pennsylvania | Registered: November 05, 2008
a 50a breaker would in theory handle 12.5kw. But normally we get 80% breakers so per code the continuous load permitted is nominally 10kw. if you can get 100% breakers for your application you can have the extra headroom.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
I have looked into getting a solar system with battery back up but just can’t make the numbers work.
First my house is extremely energy efficient and averages $150 per month. In going to the Tesla website and putting in some of the particulars of my home they suggest an 8.2 kW system with one Powerwall for a cash price of… $32,840!
Even if I could save $140 per month the payback is almost 20 Years… Of course this doesn’t include the tax credits but the payback is still over 10 years…
------------------ Eddie
Our Founding Fathers were men who understood that the right thing is not necessarily the written thing. -kkina
Posts: 6620 | Location: In transit | Registered: February 19, 2013
^^^Does the PowerWall last the full 20 or will it need replacement in 10?
Did you take into account the 10% a year you’ll be losing on the $32,840? If invested, the $32,840 would make 10% a year over 20 years.
Then there’s the 20 years. You have to live that long to reap the benefits and if you pass that hurdle, you have to stay in that house for the 20 years as well if a solar system doesn’t hold its value on resale.
The real problem with my electric bill is the fixed charges that don’t go away unless you go completely off the grid.
Posts: 12373 | Location: SWFL | Registered: October 10, 2007
Originally posted by trapper189: ^^^Does the PowerWall last the full 20 or will it need replacement in 10?
Did you take into account the 10% a year you’ll be losing on the $32,840? If invested, the $32,840 would make 10% a year over 20 years.
Then there’s the 20 years. You have to live that long to reap the benefits and if you pass that hurdle, you have to stay in that house for the 20 years as well if a solar system doesn’t hold its value on resale.
The real problem with my electric bill is the fixed charges that don’t go away unless you go completely off the grid.
You’ll probably get 20 years out of Lithium Ion batteries. I got something like 14 years out of lead acids, and when figuring out replacement, the LI batteries were rated for two and a half times as many cycles. They were more expensive though, and even at 2.5 times the number of cycles they would have been more expensive per cycle.
10% a year is a nice return. I don’t know anyone who assumes they can get that consistently.
There are so many things that can’t be pinned down accurately that I’d want a whole lot quicker payoff than 20 years. Three or four years? Sure. Twenty? Not as an investment.
Posts: 7379 | Location: Lost, but making time. | Registered: February 23, 2011
