Kill o watts

notes · February 2014

I have been reading forum for four months and learning a lot from all your post. We have a off grid cabin we are getting ready to open up for the year. We currently only have generator power. I know from reading kilowatt usage is a very important measurement of determining our needs, so I have a question on obtaining that. I purchased a kilowatt meter from grainier, my brother also has a device he can clamp on to our incoming power from generator to measure total usage, he works for out local electric utility. He said the device downloads all usage to lap top and prints it out for a 24 hour period. Anyone no about this? Do I need individual, total or both?
Andy

Cariboocoot · February 2014

Re: Kill o watts

notes wrote: »

I have been reading forum for four months and learning a lot from all your post. We have a off grid cabin we are getting ready to open up for the year. We currently only have generator power. I know from reading kilowatt usage is a very important measurement of determining our needs, so I have a question on obtaining that. I purchased a kilowatt meter from grainier, my brother also has a device he can clamp on to our incoming power from generator to measure total usage, he works for out local electric utility. He said the device downloads all usage to lap top and prints it out for a 24 hour period. Anyone no about this? Do I need individual, total or both?
Andy

What you'd get there is a measure of the total current draw over time. Not really what you need to know. The K-A-W data may be more difficult to come by (since you have to do each item individually) but it helps identify power hogs and anything that will be placing demand on the system "at the wrong time". Off-grid systems have more power available midday, when the batteries are full and the sun is still shining. If you have individual item data you can better plan when to use some of those things to take advantage of his and improve the over-all efficiency.

You don't need the power company product, but it might be fun to see what it shows.

BB. · February 2014

Re: Kill o watts

A standard Kill-a-Watt meter (US 120 VAC version) can only read up to ~15 amps maximum.

Depending on the loads in your cabin--You may be able to run all of them from the genset, or you may have to measure one or a few at a time.

Knowing both the peak watts (maximum power used) and the average kWH per day are important. The peak watts size the inverter and wiring, the average Watt*Hours (or kWH) per day size the battery bank and solar array.

You have some choices to make in what you power... A 1 kWH (1,000 WH) per day system will supply most folks that use some LED lighting, laptop, cell phone charging, and a small water pump to pressurize the plumbing from a storage tank.

As soon as you add a refrigerator/well pump/washing machine--You are looking at a much larger system (call it 3.3 kWH per day).

If your cabin uses an ice box or propane refrigerator, your loads should be pretty small (laptop, a few LED/CFL lights, efficient TV+DVD player, etc.).

If you have A/C, or other large loads--That is a whole different class of off grid power system.

-Bill

notes · February 2014

Re: Kill o watts

Thanks for info. The recording insturment will give us both peek and average watt ped day. Going to be our first season at camp starting in April. Just thought we could get a good read on our needs before we invest our dollars into this project. We have no frig, washer, dryer or ac. We do have well pump, some small kitchen appliances, and cfl and some led lighting.

Cariboocoot · February 2014

Re: Kill o watts

A well pump is one of those items I was referring to regarding using it at the right time of day: pumping up your water after the batteries are charged and refrain from running it 'after hours' will improve the system's efficiency. I know, because I do this.

notes · February 2014

Re: Kill o watts

Yes, pump and also looks like ceiling fans as well. I have a buddy who works for ABB vfd's and he wants me to pull my shallow well pump and he wants to match up 3ph motor and wire in VFD for 115 volts. I never heard of this. Is it possible?

Cariboocoot · February 2014

Re: Kill o watts

notes wrote: »

Yes, pump and also looks like ceiling fans as well. I have a buddy who works for ABB vfd's and he wants me to pull my shallow well pump and he wants to match up 3ph motor and wire in VFD for 115 volts. I never heard of this. Is it possible?

It's possible. Is it necessary, though? Probably not.

BB. · February 2014

Re: Kill o watts

A 1/2 or 1 hp would probably be more than enough--But need detail about the well (diameter, depth to water, depth to bottom of well, draw down capacity, type of pump, etc.).

A VFD gives you variable speed (match well motor RPM to actual flow needed), and soft start. You need a 3ph pump motor or three wire with a Well Head starting capacitor.

Solar power really works well with small/non-surging type loads. As you increase the loads, the size/cost of the system goes up. If it is seasonal cabin, the system does not generate any useful power when nobody is there (so poor return on investment).

In some cases, you can put a small solar power system in for "quiet time loads" evening/nigh-time loads. And use a genset for larger loads (cooking, running shop tools, recharging the battery bank during bad weather, etc).

-Bill

arby · February 2014

Re: Kill o watts

What my experience has been so far is, once you have receptacles, they will come. Microwaves, blenders.toasters.. I'm still an Electricity Nazi, but found it hard to argue with the family.

Kill o watts

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