Generator recommendations for off-grid applications

[Riley5781]

Hi guys – I know I should I post this on a generator forum (like smokestack) but us off-grid users have slightly different requirements. We need more than standby and backup type generators, Our application really requires generators that are able to handle high power battery banks (high constant load right off the bat), they need to be reliable and can handle being run daily in the winter time (maybe 4 or 5 hours a day).

Anyway, my old Onan CCK 5.0KW has died with what I believe is an unfixable engine problem.
I need to come with different solution and trying to figure out what I invest in. I have the following requirements:

- 6kw continuous output
- 240 volt strongly preferred
- propane fired
- prefer to install in my generator building to keep sound down. I have made decent investments for exhaust and cooling so that’s no problem.

I am careful how I use it in order to not overload my generator and I take good care of my batteries. I need to have my next generator last 5 to 10+ years (ie: not throw away investment that I feel a Generac would be).
I was thinking something like a new 6KW Onan but man they are expensive (and I hear of failures with them too after a couple of years).

So what do you guys recommend and use yourself to augment your solar off-grid system?

i bought a gas powered construction generator in order to buy my some time while I figure this out.

[nwdiver]

i bought a gas powered construction generator in order to buy my some time while I figure this out.

If you have the room one option could be to over-size your PV system to reduce your generator requirement in the winter so your more modest generator can meet your backup needs. I've seen panels available on eBay for as little as $0.15/w. So you can get ~5kW of PV for ~$1k these days... it's crazy.

[Salts]

You want a low RPM diesel generator. Cheaper than propane, far more reliable than the 3600 RPM units.

[sdold]

It's hard to find a prime generator in these sizes, and most manufacturers I've talked to won't warranty their standby generators if pushed into prime service, which they seem to define as anywhere without an electrical grid as the primary source, For reliability we have had bad luck with Generac, fair luck with Kohler and good luck with Cummins in the 15-25 KW propane 1800 RPM variety.

[Bala]

If you want ten years + life then you need to spec the set to around 75% continuous load, not 100 or 110%.

I havent had anything to do with propane for a long time. In Australia diesel is generally used for larger sets.

I use a 10kva twin cylinder lister diesel. They are noisy and air cooled but I built it an insulated shed so it is ok. No cooling system to maintain or belts to break.

It has only done 2200hrs in 14 years and had only an oil pressure sender fail. Life expectancy 40,000hrs.

It is for the most part not loaded enough but I need the size for welding.

[Mike90250]

What sort of climate are you in? Will snow coat the 20 extra PV panels you install ?

if you need 6kw, you install 9Kw rated (for your fuel) My issue with the new alternators on gensets, is they are very light and marginal in their specs, with poor PF. I have a .3.KW diesel that will barely push 2Kw before the power quality goes to hell (so it's backup to the main generator in my .sig ).

Honda engines are pretty reliable. maybe one of their open frame gensets in the 8-9kw class would work. Just lots of oil changes with air cooled, but no water pump, coolant, or fan belts to worry about either. Yamaha might be the next choice.

[Riley5781]

Thanks for the responses guys. I'm in Western Canada and we do get snow that covers panels. I have learned from this forum and through practical experience, to live off grid and take care of your batteries, you must have a generator. I could de-rate and only pull 3.5KW to meet the charging needs of my 420AH 48V battery bank but would rather charge at 80 amps instead of 40 amps.

I really want to avoid diesel due to the smell and fuel hassles. Propane is cleaner, easier and the exhaust doesn't stink.
I will look at Honda but was thinking about an RV/mobile genset like an Onan or Kohler but concerned they might not last that long.

[SunEagle]

Thanks for the responses guys. I'm in Western Canada and we do get snow that covers panels. I have learned from this forum and through practical experience, to live off grid and take care of your batteries, you must have a generator. I could de-rate and only pull 3.5KW to meet the charging needs of my 420AH 48V battery bank but would rather charge at 80 amps instead of 40 amps.

I really want to avoid diesel due to the smell and fuel hassles. Propane is cleaner, easier and the exhaust doesn't stink.
I will look at Honda but was thinking about an RV/mobile genset like an Onan or Kohler but concerned they might not last that long.

IMO a Kohler, Cummins or Onan will last longer than a Generac if you need to run them a long time.

[Riley5781]

IMO a Kohler, Cummins or Onan will last longer than a Generac if you need to run them a long time.

Thanks SunEagle, want to hazard to guess how many hours I could get out of a new Cummins or Kohler?
I figure I might put on 300 to 500 hours a year and wondering if I could get 5000 hours out of one of these new gensets.

[Mike90250]

There is something to be said for buying a pair of 9kw construction site generators, and alternate the daily or weekly running. Wear them down evenly, and you always have a spare When one dies, buy a 3rd and you are still $ ahead of a $15K generac, but it's not automated.

Propane conversion kits are avaib for nearly all generators. As ambient temps get colder, propane becomes harder to evaporate from the tank ( ever see a BBQ tank with frost on it on a summer day as you draw off the propane ?) Sometimes you will need a 500Gal tank to run a large genset because of the evaporation cooling factor of propane. Ther are temp and Hp charts avaib for sizing the tank.

Scroll down to the
Propane Tank Vaporization Rates section :

http://www.engineeringradio.us/blog/2010/10/care-and-feeding-of-propane-fueled-generators/

[Riley5781]

There is something to be said for buying a pair of 9kw construction site generators, and alternate the daily or weekly running. Wear them down evenly, and you always have a spare When one dies, buy a 3rd and you are still $ ahead of a $15K generac, but it's not automated.

Propane conversion kits are avaib for nearly all generators. As ambient temps get colder, propane becomes harder to evaporate from the tank ( ever see a BBQ tank with frost on it on a summer day as you draw off the propane ?) Sometimes you will need a 500Gal tank to run a large genset because of the evaporation cooling factor of propane. Ther are temp and Hp charts avaib for sizing the tank.

Scroll down to the
Propane Tank Vaporization Rates section :
http://www.engineeringradio.us/blog/...ed-generators/

Thanks. I might look at converting a Honda to propane. That's an option.
I do have a 500lb tank and large distribution line to the generator shack.

I did buy a 7KW construction site gas Yahama yesterday just to ensure I don't kill my batteries while I sort this out. I was thinking of keeping it for a backup.

[SunEagle]

Thanks SunEagle, want to hazard to guess how many hours I could get out of a new Cummins or Kohler?
I figure I might put on 300 to 500 hours a year and wondering if I could get 5000 hours out of one of these new gensets.

You really have to read the generator specs to know how many hours you can put on it before specific maintenance is required.

All I know is that Generac is only rated for standby use with minimum hours per each use. I have a 3250watt propane unit but it has seen very little use since I purchased it about 6 years ago. But some of my friends that have a Generac whole house unit have had to get it rebuilt after long hours of use.

[Andy Muzik]

I have two Honda EU2000I propane converted. One has over 3000 hours. We are very happy with the longevity of this product. All as I can saw is maintenance,maintenance,maintenance.

https://genconnexdirect.net/index.htm