theboss:
ok 3-6kwatt
how many hours a day total run time anticipated?
how many hours at 3kwatt?
how many hours at 6 kwatt?
can you reduce comsumption?
can you schedule some, part or all of your heavy loads
have you done an analysis of your projected kwatt/hr needs?
the main reason i ask these questions come down to what it will take to effectively size your genset
without any concern for conservation, and without regard to any scheduling,, you might find you need 25 plus kwatt of genset to cover
your loads, vs with heavy conservation and meticulous scheduling you might get by quite nicely with 2.5 kwatt in genset capacity.
you success at conserveing and scheduleing will determine which end of the scale you will fit in.
other factors are run times,
if you incorporate a battery bank and an inverter, you might be able to run the genset as little as a couple of hours per day as opposed to 16-25 hrs per day
depending on how well designed your system will determine where on this scale you fit in.
ben franklin had a saying "a penny saved is a penny earned" (which is more like a penny saved is a nickle earned today)
this holds true of generating your own power.
the problem as i see it with trying to base a system on one parameter, (engine efficiency) is problematic.
i assert that you really need to look at the whole project as a complete system, and then work to improve efficiency of the overall system.
when you start to think through the processes of the complete system it will become apparent that perhaps an engine that is a percent or two
more fuel efficient might not fair as well in the total system efficiency for various reasons.
an example
system A:
engine uses 1 pint of fuel to run one hour and produce 1 kwatt of electrical power, this power is used to charge the battery bank for use
during the rest of the day. to charge the batteries using a high capacity automotive alternator you find it takes 4 hours to charge the batteries
total fuel used 4 pints
system B:
engine uses 1.5 pints of fuel to run one hour and produce 1 kwatt of power, this power is used to charge the battery bank for use during the rest of
the day. to charge the batteries using the same alternator but replaceing the automotive regulator with a smart controller and an efficient charge regime
you find that it takes only 2 hours per day to charge the batteries.
total fuel used 3 pints
now this example though exagerated for purposes of illustration (you wont find anywhere near this disparity in comsumption in the real world) clearly shows
the importance of other element of the overall system.
and this is only one part of many in determining the answer to your question.
perhaps i need to work on developing a questionaire form that has a scoring system, which would aid in getting an answer to what and why.
questions such as (on a scale of 1-10)
1. can you schedule none, some, part or all of your heavy loads (score 1 for none, 3 for some, 6 for part, and 10 for all)
2. do you anticipate using batteries, or are you comfortable maintaining batteries ( no batteries 1, uncomfortable 3, comfortable 6, yes i want them 10)
3. are you mechanically inclined? ( score 1 for not at all, score 3 for somewhat capable, score 6 for accomplished DIY guy, score 10 for mechanic, electrician etc)
4. do you want a system that is fully automated, electric start etc? (score 1 for fully automated, score 3 for some auto controls, score 6 for mostly controlled, score 10 for no controls, i will do it myself)
5. are you grid or offgrid (score 1 for ongrid and backup power only, score 3 for grid and some regular power, score 6 for most power from genset, score 10 for offgrid)
etc etc.
might be a 100 question form,, but the results of which would likely show clearly what type of equipment is suitable for the user
and it would illustrate to the user area's where he might make some changes in lifestyle, education, time management, scheduling etc. might skew his result
to something more in line with what he thinks he wants.
might be an interesting project
bob g
