Question on generators & inverters for off grid living (Anchorage: appliances, house)

[igloo]

Looking a property west of Anchorage that is off grid, and knowing nothing yet (but will be studying on the subject) of generators, inverters and battery systems. The property in question shows the following information.

"Electrical power is supplied by 8 deep cycle batteries tied to a 5.5 Kw inverter. The batteries are charged by diesel generators (8 Kw & 5 Kw), solar panels and 900 watt wind generator. The 8 Kw generator has automatic charging controls as well as the solar and wind generator inputs to the batteries."

The property (2100 square feet, has been in existence for several years so the systems in place must be pretty efficient for the needs of the home, etc.

Question: Does a generator have to run all the time with this type of system, or just a few hours a day. I would imagine that the answer would depend on what is being run at the time, i.e. TV, internet, washer/dryer, water pump for bathing, etc. If anyone can give me some feedback on what I have listed on this posting, it would be appreciated. I realize that there are generalities here, but any info would be helpful.

[Moose Whisperer]

Yes, the generator will only run as needed to charge the batteries when the solar panels and wind generator aren't enough. The way it's described it also sounds like the 8 kw generator will probably autostart when the inverter senses low battery charge. Only one 5.5 Kw inverter for the entire house seems a little small to me, but it sounds like that's what the 5 kw generator is for - supplemental power for running really big loads like doing laundry or running power tools. Your major expense on a system like this will probably be changing the batteries every few years.

[starlite9]

Roughly, it take the same amount of time to charge deep cell batteries zero to 80% as it does from 80% to 100%. So for fuel economy, most will shut off the generator at 80% or so, unless they are using it for other power supply systems like running a dryer or the like.

The batteries will have a life cycle as well, so you want to find out how old they are, they may need replacing if more than five years or so and depending on how many cycles they have done and charge status.

ONLY 2100 square feet of property or the cabin size? That is like 42'x50'+-, not very big. That is most people's driveway.

[igloo]

Originally Posted by starlite9

Roughly, it take the same amount of time to charge deep cell batteries zero to 80% as it does from 80% to 100%. So for fuel economy, most will shut off the generator at 80% or so, unless they are using it for other power supply systems like running a dryer or the like.

The batteries will have a life cycle as well, so you want to find out how old they are, they may need replacing if more than five years or so and depending on how many cycles they have done and charge status.

ONLY 2100 square feet of property or the cabin size? That is like 42'x50'+-, not very big. That is most people's driveway.

I should have clarified that the 2100 SF is the size of the house, not the property. Thanks for bringing that to my attention.

[RayinAK]

Just keep in mind that it's a good idea not to overload the inverters nor the generators past 75% of its total power for extended periods of time. You can add the total wattage (power) to be used by the appliances all at once, and this will give you an idea of the total running power used by such components. However, if any of the components uses a motor, then you have to take into account the starting power needed for the motor to start running. But I imagine that if you can figure the total running wattage used by all of the components you plan to run at once, and can keep this number (running power) around 75% of the generator's capacity, then the additional starting power (if needed) won't be a problem since it's momentary. Once a motor is running at normal speed after a start (the well's pump, for example), then the power-use level comes down.

The power use (shown in Watt) can be found at the component's ID plate along the part and serial numbers. The clothes dryer will use both starting and running power in addition to the heating element power use. But components without motors (coffee maker, clothes iron, light bulb- for example) don't use starting power. Most generator manufacturers post clear explanations on generator capacities, and the powers I am referring to.

[chrislly]

wow, that is great!!

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