Powering house from idle bus?

[ermracing]

Just wondering here. Once we get our bus outfitted with solar/battery bank/inverter and all those goodies, what can we do with it while it sits in the yard between rallies and road trips?

Does anyone run power from the bus back into the house to run some appliances? Figuring this would have to be with just a good extension cord (10Ga?) and not into the house breaker box or anything.

How about feeding it back into the grid to earn some $$?

[Pizote]

A small diesel engine that powers the bus is not efficient and is prohibitively costly in the long run to power a home. Then there are the problems of noise and environment pollution - burning diesel is worse than natural gas.

You will need to install disconnects to the house to install the "generator" so that if the power from the grid comes on, you will not overload the system (or controller units similar to solar systems). Likewise, if the grid power is off, you want to disconnect so that no other homes draw from your engine and overload the generator. Also, unless your generator is 220vac, you will only be able to power one side of your house unless you come up with some creative-backwoods solutions which are never recommended.

It's a good idea for short term power outages (we hooked our RV generator up to one leg of our house to power minimal lights and the fridge), but it will never save you money.

[ermracing]

Just to clarify, I was just wondering about the 110v output from the battery bank, not from a generator. We already have a generator that we use for power outages. I'm just thinking about running an extension cord from the bus (sitting in the driveway) into the house to run some random appliances.

The thought about feeding the grid would require going through the local power company of course, with the appropriate switches. Just wondering if anyone else has done this?

[Pizote]

Same issues arise with any power source. 110vac is 110vac is 110vac.

Your house won’t know the difference between grid, generator, solar, wind, etc.

The quick answer is that yes you can do that but to conform to code and be safe, there are modifications that need to be done for protection in your home.

[john61ct]

The consumer cost of grid power is a tiny fraction of any small scale alternative power sources.

From battery storage triply so.

The government may **force** utilities to buy consumers' excess green power in order to encourage investments in its deployment, but utilities would never do so otherwise, and in fact continuously are spending big money to reverse such policies.

[o1marc]

Originally Posted by Pizote

Same issues arise with any power source. 110vac is 110vac is 110vac.

Your house won’t know the difference between grid, generator, solar, wind, etc.

The quick answer is that yes you can do that but to conform to code and be safe, there are modifications that need to be done for protection in your home.

Not if he's not tying into the house grid. He just wants to plug separate things into an extension cord from the inverter.

[Iceni John]

A fellow Crown owner who has an off-grid cabin in OR and 1680W of solar panels on his bus does just that - in the summer he sends his bus's power to the cabin. In the winter he leaves his cabin and drives to Mexico or other warmer climes. So, yes, its doable to power a house from a bus, assuming you have sufficient PV power and a small enough house.

John

[john61ct]

But doing so makes sense because the cabin is just as off the grid as the bus is.

[semipro]

Wow. I just wrote a lengthy response and was told "my token expired" when I tried to post it. Lost it all too.

Moving on:
I've been thinking of this approach also with a bus we'd get. Two challenges I haven't wrapped my mind around though:
1) Anti-islanding protection
2) Federal tax credit qualification

[roach711]

Anti islanding protection prevents your solar feed from back feeding the grid in a power failure situation. It's a safety feature that keeps repair crews from being shocked by wires that should have no current flowing.

[semipro]

Originally Posted by roach711

Anti islanding protection prevents your solar feed from back feeding the grid in a power failure situation. It's a safety feature that keeps repair crews from being shocked by wires that should have no current flowing.

Yes, and this feature is typically in the inverter. If you do something like the OP suggested with battery backup you'd probably want to access that power in the house during a grid failure. Since the inverter is located in the bus and you want to provide power to the house how would anti-islanding be accomplished? The inverter would effectively see the house as the grid and shut down flow to the house - not what you want. It seems you'd need some sort of remotely operated contactor located in the house that disconnects from the utility grid based on a signal from the inverter on the bus.

[ermracing]

Maybe we should install a small breaker box that feeds a few outlets in the house? That way we can connect the bus inverter to the breaker box and not the grid.

[Pizote]

Originally Posted by ermracing

Maybe we should install a small breaker box that feeds a few outlets in the house? That way we can connect the bus inverter to the breaker box and not the grid.

Here's a diagram of solar to connect to a house.

You will need to add three things to this diagram. Before we start there, your bus/solar will be everything from the inverter through the solar panels.

To the left of the inverter, you will need to install an AC Disconnect (we will call it Bus AC Disconnect) to the house.
To the left of the AC Breaker panel - between the breaker panel and the utility meter, you will need to install another AC Disconnect (called Grid Source AC Disconnect).
Between the inverter and the Bus AC Disconnect, you will want an outlet with extension cord rated for your solar system on both the house side and bus side.

Order of operations would be the following:

• Connecting solar to house
  • Verify Bus AC Disconnect is turned off
  • Turn off Grid Source AC Disconnect
  • Connect Bus to house
  • Turn Bus AC Disconnect On
• Reverting from Bus to Grid power
  • Turn off Bus AC Disconnect
  • Disconnect bus from house
  • Turn on Grid AC Disconnect

[roach711]

Originally Posted by semipro

It seems you'd need some sort of remotely operated contactor located in the house that disconnects from the utility grid based on a signal from the inverter on the bus.

The cheap answer would be to manually disconnect your house from the grid by flipping the main breaker in the house main panel.

Our house has a small transfer switch that allows certain circuits in the house to be either on grid power or on generator power but not both. That way we can power most of the house from the genny and still have some circuits hooked up to grid power so we get instant notification when grid power comes back up. Installing the transfer switch requires some re-wiring of the main panel.

Looking around on the 'net last night I saw some anti-islanding relays for sale. Those may be a cheaper alternative than an anti-islanding inverter.



As a practical matter, if you didn't disconnect from the grid and tried to power your house you'd effectively be attempting to power up the dead portion of the grid with your small solar array. I know a small generator will stall or shut down when overloaded. Not sure what would happen to a solar array but I don't imagine it would be anything useful.

[roach711]

Here's the 30amp transfer switch we installed. I ran a cable from it out to the garage so I can hook up the generator but a mobile solar array would be equally simple to hook up to. You'd need to come up with a safe way to run an extension cord from the bus to the garage power inlet (no hot male connectors!).

Your genny or solar array powers the transfer switch so there's no chance of back feeding the grid.

https://www.youtube.com/watch?v=7--oK3BXN5U

[ermracing]

Thanks for the replies. We currently backfeed the main house panel from our generator (non-bus related) and simply kill the main, street side, breaker when the grid goes down. I think we'll just wire in a separate panel to be fed from the bus and plug in a few things to use the 'free' power, even when the grid is up. This system would not connect to the grid in any way, just to keep it simple.

[BlackJohn]

" We currently backfeed the main house panel from our generator (non-bus related) and simply kill the main, street side, breaker when the grid goes down."


...but you are livening up the neutral on the grid side. That can kill a lineman not expecting it.


John

[ermracing]

Originally Posted by BlackJohn

" We currently backfeed the main house panel from our generator (non-bus related) and simply kill the main, street side, breaker when the grid goes down."


...but you are livening up the neutral on the grid side. That can kill a lineman not expecting it.


John

Even if we shut off the main 200 amp breaker?

[BlackJohn]

Originally Posted by ermracing

Even if we shut off the main 200 amp breaker?

Yes, it is possible, more so when the grid is shutdown. That's when they are least expecting any backfeed on any of the conductors they are working on.\


In your house panel, the neutral is still in play even though the main breaker might be shut off. If it is off and you are connecting your "bus hot power"
to the main panel somehow then the neutral definitely will have the unbalanced load on it. That has to go somewhere, guess where?
Yup, back onto the grid.
You could be sued bigtime for that eventuality.



John

[BlackJohn]

Dave, can you post pics of how your auxiliary power is connected to the house main panel?
I thought you were using your bus as the off grid source but it appears not after reading thru this again.
Very curious to see how you made connections for both hot bus bars and neutral bar.
Pics would sure help explain to me and others here what you have there.
Thanks,



John