[RE-wrenches] Question on Back up generators

Jerry Shafer jerrysgarage01 at gmail.com
Wed Apr 8 18:01:33 PDT 2015


We don't install anything smaller then a 13 k its air cooled but works
well, as far as the numbers you have, Mine are somewhat different I use max
potential load and max potential charge as when the batteries are low the
genny must not only supply the home but also charge the bank back up at a
reasonable rate, so if the loads are high and the genny only has enough to
maintain that load then what about the batteries plus I only use 75% of the
genny rating for optimum or improved duty cycle. This is only me and I am
sure every shop has there own math.
Jerry

On Wed, Apr 8, 2015 at 11:23 AM, Dana <dana at solarwork.com> wrote:

> Hey All –
>
>
>
> I just got off of a phone call with my Onan generator supplier. Last
> conversation with Kohler was the same story basically.
>
>
>
> I was informed that their smallest water cooled generator, the RS22 (22
> KW) is now no longer “rated “for off grid. They actually called me to
> confirm that this generator was for backup power to a utility inter
> connected house. Tier 4 generators in the EPA CFR 40 is the Federal code
> what covers this, & you are allowed 100 hours of run time for standby power
> and maintenance per year.
>
> Q - Why am I using ridiculous sized generators for something that an
> 82-8300 watt generator does just fine?
>
> A - The EPA current requirements, a shrinking economy, & manufacturers
> that have to meet very expensive air quality compliance.
>
> The Penalty - If you get caught running a “standby power only” generator
> the fine is now $39,000 per day!
>
> Now I am far from a polluting kind of individual and all for air quality
> but this is getting the best of us. The 13KW air cooled generators are only
> good for 2000 hours, & the water cooled go 20 years of moderate usage but
> cost a boat load. I hate having the “Generator” talk with a new client they
> look at me like I am crazy. So the air cooled units are basically
> throwaways and the 22KW units are way more than we need and what a client
> needs to spend money on, unless you are at 10,000 ft el.
>
>
>
> If you figure 30 amps/120 VAC input per inverter +/- x 2 = 7.2KW plus say
> 10-15% fudge or elevation factors would require an 8200-8300 watt
> generator. Air cooled at 3600 RPM = 80 MPH & 1800 RPM = 40 MPH.  Even if
> the generator were a bit smaller, ran slow (1200-1800 rpm) and ran a bit
> longer that would be acceptable.
>
> So, why are we installing even 13KW air cooled or 22 KW water generators?
>
> There is a business opportunity here folks.
>
>
>
> What are you all installing?
>
> Why?
>
> Is it reliable?
>
> Would you use it on your house?
>
>
>
> Thanks for sharing all the wisdom and knowledge.
>
>
>
>
> ----------------------------------------------------------------------------
>
> *Dana Orzel*
>
> *Great Solar Works, Inc -  NABCEP # 051112-136*
>
> *E* - dana at solarwork.com  - *Web* - solarwork.com
>
> *O* - 970.626.5253  *C *- 208.721.7003 - No FAX Line
>
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