Making a wise generator choice?

ligwyd · December 2018

I'm sure this topic has been beaten to death simply based on system design requirements, fuel source, budget, reliability etc.

However, Is there a "10 commandments" to generator selection when designing an off grid power system?

Originally I liked the idea of a smaller lower rpm Kubota powered diesel generator due to quality/ longevity and best bang (most power) for your buck with fuel consumption.

Now I am considering the possible continual refilling mess (guess that could be mitigated with an external fuel tank) and that It may not run enough to justify spending the cash on a prime generator (designed for round the clock usage). Then again you'd only buy it once and you could pass it on to the boy.

Questions many have already been through that I am hoping to lean from.

Appreciate any input that others may have to add to this topic.

Thank you

Estragon · December 2018

A good discussion:

https://forum.solar-electric.com/discussion/16206/choosing-a-good-generator/p1

IMHO, a good generator is worth the investment in many (but not all) off-grid situations. In some, more southern climates, folks are blessed with reasonable solar year-round. In my case, solar is pretty reliably unreliable from ~Oct to Jan between low sun angle, short days, and seasonably gloomy weather. A smallish low RPM diesel (c.1982) does the job for me in that period.

mcnutt13579 · December 2018

Where are you located and how much do you expect to use the generator are the most important questions here.

jonr · December 2018

Also consider propane. And capturing the waste heat for the house (space heating and/or hot water).

mike95490 · December 2018

Will you be integrating the generator with a charger or an inverter/charger ?

I am fairly happy with a 3kw slow speed diesel generator. Fuel is about as universal as it gets. Crankcase oil is the long term show stopper.

My basic house loads are 300w roughly, and the generator will run the pump and start the fridge. I dont have air conditioning.

softdown · December 2018

While I have a good diesel generator I still lust for a propane genset. Diesel doesn't cotton to very cold weather and that is exactly when solar is most likely to come up short. Diesel is also loud and somewhat expensive for fuel and very expensive if significant repairs are needed.

Propane is often cheap if bought in quantity in August. Last forever, burns clean, doesn't clog carb jets, and doesn't mind the cold. Not saying propane is for everybody but it is worth considering for many.

For very heavy usage? Then low rpm diesel shines like the sun.

I live in a very sunny alpine desert so my perspective is often unique from those who suffer from cloudy winters in the frozen north. They may take heart in the fact that I find northern folks to often be a cut above their southern brethren. #QualityMatters

t00ls · January 2019

oh my ..the generator discussion

diesel:
pro: low fuel consumption
con: loud, needs the oil changed a lot, not good in cold weather

gas:
pro: you can convert to tri-fuel using NG and LPG along with regular gas, easy to maintain, works in all weather
cons: uses a lot of gas when running on gasoline

sizing: depends on the loads you want to run, cant go wrong with at least 3500w continuous

also depends on if you have an inverter that incorporates generator power....size it just above the inverter size because most generators like to run at half load efficiently

watch out for advertising....7000w, when in reality that is probably the surge rating for so many seconds

look for the continuous output rating

as an alternative to a backup generator for charging batteries on a cloudy day, if you have a creek, you can do micro-hydro, if there is enough flow or head
or
if you have a lot of windy days, build a hugh piggot type wind turbine
https://www.scoraigwind.com/pirate oldies/Hugh Piggott Axial-flow PMG wind turbine May 2003.pdf

good luck

Making a wise generator choice?

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