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 <r...@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 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org