Cummins Onan RS 20000

Mangas
Mangas Solar Expert Posts: 547 ✭✭✭✭
in Solar Product Reviews & Opinions #1
Happily, replaced my Generac SG015 with a new Cummins Onan RS 20000 (20 GGMA-6111), 20 kw propane generator for our off grid system.

At our 5,000 altitude it's derated to about 18.4 kw (>3,000 feet @ 4% per 1,000ft).

First impression, very well engineered product and high manufacturing quality. Equipped with an electronic governor versus an electro-mechanical one, 3.0 L motor, 90 A breaker, brushless exciter power output and easy maintenance access.

The unit is very quiet (66 dBfull load) and fuel consumption is not excessively high.

Their warranty is subject to the type of hours it's asked to do. For our off grid application (limited hours on line during the year) it should be well within their warranty standards. Our system's SW U.S. 24/7 seasonal capacity asks the generator to run about 60 - 80 hours (occasional day @ 2 hrs at a time) a year including short exercise runs. Having seamless power available for the ranch regardless of weather/solar conditions is a mandatory system design requirement for us.

After living 5 years with our off grid system, we recommend investing in a high quality and reliable genset to bridge reduced solar conditions. In our case, < 150 hours per year of generator time was our target for not not adding more panels and battery storage. Just our windage on how to balance the hardware.

This genset is a very nice unit.
Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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Comments

  • Frxddy
    Frxddy Solar Expert Posts: 113 ✭✭✭✭
    #2
    Re: Cummins Onan RS 20000

    Congrats on the new generator! She sounds like a beauty.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #3
    Re: Cummins Onan RS 20000

    Curious what prompted replacing the Generac? Also, if you are using your new generator on a regular basis you don't need to do the weekly exercise.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #4
    Re: Cummins Onan RS 20000

    Purchased in 2006 the Generac unit only had 450 hours on it and ran infrequently, about 80 hours a year including monthly exercise time. Our off grid genset requirements are light duty only needing occasional early morning back up totalling about 60 - 80 hours a year at 2 hour run intervals. The genset exercises itself at midnight for 20 minutes once a month.

    The last three years, we had to replace the Generac alternator, voltage regulator, coolant level sensor, auto governor steppermotor twice, and had recurring slip rings and brush problems all which shut the unit down when it was needed most.

    With emergency service 150 miles away and parts even further it was very expensive to fix and maintain.

    As posted, my first impression is the Cummins Onan is a first class product. It is a very quiet, well manufactured and powerful unit with a warranty perfectly suited for our limited off grid solar needs for generator back up.

    We'll see how it performs over the next few years.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #5
    Re: Cummins Onan RS 20000

    Sorry to hear about all the problems you had with the old one, here's hoping the new one does better.

    At 60 hours per year that's a minimum of 5 hours each month, way more than enough to ensure your seals will stay lubed and the brushes clean. If your new unit will allow you to not set an exercise time, you could get away with saving 4 hours of fuel each year. If I don't set one with mine it just flashes a warning light at me.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #6
    Re: Cummins Onan RS 20000

    The Cummins Onan has an exciter rather than slip rings and brushes which was very problematic on the old unit.

    The generator runs it's 60 hours or so mostly in between June-August (summer rains)and December-March (winter low solar/winer rains) periods. Otherwise it rarely comes on.

    We've programmed the inverters to run the exercise schedule. I was told once a month was sufficient added to its demand runs.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #7
    Re: Cummins Onan RS 20000

    Photo of the installed RS 20000.Attachment not found.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • dagr51
    dagr51 Solar Expert Posts: 72 ✭✭✭✭
    #8
    Re: Cummins Onan RS 20000

    THAT is cool! Thanks.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #9
    Re: Cummins Onan RS 20000
    dagr51 wrote: »
    THAT is cool! Thanks.

    Actually, when it runs it is rather hot. :cool:
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #10
    Re: Cummins Onan RS 20000

    It's very quiet and seems to be as fuel efficient (3 liter engine) as my previous 15 kw unit.

    Apart from their larger 30 kw CumminsOnan, they should consider offering a brushless 15 kw genset.

    Their customer service is first class. Responded with a detailed answer to a question I had the same day.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #11
    Re: Cummins Onan RS 20000

    Glad to see no naked generator pictures. ;)

    -Bill "moderate moderator" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Mangas
    Mangas Solar Expert Posts: 547 ✭✭✭✭
    #12
    Re: Cummins Onan RS 20000

    Bill,

    We're a little old fashioned out here. Out of respect and decorum, I left the access panels on.

    Doors off this summer. Y'all look the other way!
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF Custom House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #13
    Re: Cummins Onan RS 20000

    Get our motor running.

    Gotta love magnetic attraction.

    Ok, I'm fresh out of bad jokes to add... :cool:
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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