[RE-wrenches] diesel vs. solar

[Dan Fink]

I totally agree with Ray.

Generator scheduled maintenance is a huge issue that I have not seen
quantified monatarily.

The dire de-rate factors from every piece of software and every
spreadsheet we've tried seriously underestimate actually off grid
system performance we measure in the bush -- that's the correct
direction to be off on the calcs, but still.....

Same with generator de-rates for altitude. They de-rate the
performance of the engine, but not the electrical output. Some engines
deal with it far better than others.....

And
Dan Fink,
Executive Director;
Otherpower
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
970.672.4342




On Mon, Mar 25, 2013 at 9:18 AM, Ray Walters <ray at solarray.com> wrote:
> Also, Windy Dankoff's old spread sheet that I adapted calculates generator
> run time per week, and Maui SOlar software does a good job of calculating
> generator hours per year.  I've used Homer and found it to be pretty far off
> from off grid reality.
> Any off grid application is going to benefit from inverters and batteries to
> keep the generator from having to run 24/7.  Next, adding at least some PV
> to trickle charge the batteries is often a no brainer.  . You definitely
> don't need as much battery in a hybrid system.
> Its not just a fuel issue, generator replacement and maintenance, along with
> more esoteric considerations like noise, and smell, need to be factored in
> as well.
> Figuring the ratio of generator run time vs. PV is a bit trickier, but I
> found you can sneak up on that calculation by starting with the generator,
> batteries, inverters, and smallish PV, then add more PV incrementally while
> monitoring gen run time.
> Real performance numbers always beat computer simulations, especially off
> grid, where it is often tough to characterize the real life complexity of
> the loads.
> There is a point if your baseline 24/7 loads are large enough, a full time
> generator makes sense, but unless its in Alaska, some PV almost always makes
> sense as well.
> Also the loads will determine how much design time to put in before hand.
> If your looking at a 50kw generator or up, you need to invest in some
> software and/ or get an off grid design specialist on board.
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760