Generator backup power

[techman]

It is unlikely your generator will catch fire, the breaker should trip. The big problem is that without an interlock you could backfeed into the power line and possibly kill a lineman working on the outage problem. You don't want that.

paul

 

[techman]

What happens if you disconnect from grid, run on generator while solar PV is powered up.

I have found that when the generator frequency is within the tight frequency spec of the gridtie inverter it does supply to the house. Problem is if you generate power with solar greater than the current load, the generator cannot take up the excess. If the generator has an active voltage regulator, as the volts rise the gen will start to back off. It will either sysle the solard on and off, or in a worst case you could damage the generator. I allow the solar breaker to be on if I have a good load (like hw heater) active.

paul

 

[LittleBill21]

It is unlikely your generator will catch fire, the breaker should trip. The big problem is that without an interlock you could backfeed into the power line and possibly kill a lineman working on the outage problem. You don't want that.

paul

he's talking about keeping the generator energized while switching to live power, not an outage. if he's out of phase far enough when he goes to trip the breakers the generator head will try to come into sync with the grid power. that can end very badly

 

[wagne223]

he's talking about keeping the generator energized while switching to live power, not an outage. if he's out of phase far enough when he goes to trip the breakers the generator head will try to come into sync with the grid power. that can end very badly

Plus destroy every electric item in the house.
During that split second when changing sources and phases, a lot of bad expensive things can happen.

Most people do not understand phasing and frequency.

When switching from backup power back to utility, I wait 5 minutes for everything to settle down.

Probably not necessary but I'm not pressed for time and it makes me more comfortable.

 

[Larry Caldwell]

I have found that when the generator frequency is within the tight frequency spec of the gridtie inverter it does supply to the house. Problem is if you generate power with solar greater than the current load, the generator cannot take up the excess. If the generator has an active voltage regulator, as the volts rise the gen will start to back off. It will either sysle the solard on and off, or in a worst case you could damage the generator. I allow the solar breaker to be on if I have a good load (like hw heater) active.

paul

He's talking about keeping the solar inverter energized during a power outage. For safety reasons, when the power goes out so does the solar or wind power backfeed into the grid. Essentially it shuts down your system. If you energize it with a generator it will pick back up and deliver power, but you have to have somewhere for the power to go. That means big batteries with a charge regulator that will give you a power reserve, including surge reserve. It adds a substantial layer of complexity to a solar installation, but it can be done if well designed. A power system not connected to the grid will have the batteries, but not an intertie that has to be hot to activate the system.

 

[3930dave]

OP - if you haven't seen this, checkout Paul's build:

Custom Generator Shelter - YouTube

4Shorts on here - quiet lately, and I'm glad to see on Youtube that he is doing well. (2 heart attacks earlier this year).

IIRC, Paul used to be a Honda small engine tech, so he knows that generator well. Everything he builds is first class. Vid is worth watching just for the construction techniques, and ventilation setup.

Two things to consider re. proximity:

1) Sound transmission. If you have the space, it's usually a lot easier to remote the shed than to try and mitigate noise transmission after you build against the house and then find out you have a problem.

2) Fire/Code/Insurance....... I have no idea of your particulars, but suffice to say that in most areas a detached garage is cheaper to insure than an attached one. After building an attached shed is not a great time to find out your insurance company is threatening to cancel (worse yet, during a claim).

Rgds, D

 

[fatjay]

That was a good video that raised a few points to consider. Almost all of them have to do with snow. Opening the lid with 3' of snow on it is going to be a challenge. Folding the front down as well. Also the air ventilation for cooling isn't very high off the ground, easily causing it to get plugged with snow and if the snow melts, then refreezes, ice.

My plan is to make it about 6-7' tall at the lowest point, and having a split door where I can just open the top portion. 90% of the time I lose power is when it's a heavy snow storm, so it makes sense to build it taking into consideration the difficulties of snow. I wish he'd gone into more detail of how he hooked his exhaust up. Is it bolted to the generator or just up against it? I was thinking of bolting it, but the vibrations might be hard on the welds if it's in a fixed location in the shed. Or, given the volume of the shed, 5'L x 6'W x 7'H, would just sufficient ventilation be good enough to not need a separate exhaust?

 

[Sawyer Rob]

I see no reason why a pto gen set can't be put in a small enclose/building by the house and bolted to the floor. Heck, it could be big enough to include a tractor too...

When the power goes out, hook up the pto shaft and start the tractor. Once it all warms up a bit start adding load...

Heck, the generator could be mounted in the back corner of my garage with a hole in the wall for the pto shaft to go through. (with a small door of course)

Mounting/wiring a pto gen set in an enclosure is no different than mounting any other gen set in a small enclosure.

SR

 

[zzvyb6]

Your notion of a pto generator kept in a small "dogg house" is very common, especially on farms to run the milk-house and grain dryers. Having an older tractor around with a good motor (like a 4020) is commonly on-station around here ready to rock & roll as needed.

It is a good idea to have the PTO shaft outbound, though and on a trailer in case you need power outside the range of utilities and even when the neighbors need some heat, water or refrigeration.

 

[Larry Caldwell]

Dairy farms live and die on their power supply. I had a neighbor a few years ago who milked 1000 cows. He had a 75 kw, 3-phase PTO generator that he powered with a 150 hp JD tractor. He had substantial on-farm diesel storage, since his silage chopper used twin 300 hp diesels that sucked fuel like a garden hose. He hired about 40 guys to keep things running, so didn't waste any time in the fields. That may seem like a lot of help, but milking 1000 cows 24/7 while feeding and manure handling plus field work and giving the guys some days off requires a lot of employees. During storms he kept the tractor hooked up and ready to start.