Grundfos SQFlex

[PVCabin]

I am in the process of figuring out my wattage use for an off-grid cabin. The wells in the area are notoriously deep-around 400', I am planning (may change once I actually drill the well) on using a 1/2hp Grundfos SQFlex (AC pump), but I cannot find any information on how much power they will use to operate- I know it depends on how much water I will use, but just curious if anyone knows how much power they draw? Does anyone have any experience with these pumps? I know they have a soft start, which is why I am leaning towards using them.
Also, how much power does a pressure pump (around 65g) use to operate? (1-2 people, 3-4 days/week).
Thanks!

[Mike90250]

I've heard a "rule of thumb" (depending on your thumb size) of 50 gallons / day / person.

Do you have an elevated tank that provides gravity pressure, or a ground level pressure tank (with air bladder inside) ? Generally, the larger the pressure tank, the more time between pump starts, and pump starts really eat power. If you have one pump at 400', feeding a pressure tank, you need to figure on 400' feet of lift, PLUS the additional lift needed to pressurize your tank - maybe 500' lift needed to get 50psi into the tank. The calculation is on the web, about .4 psi per foot of elevation.

[PVCabin]

I'm going to have a pressure tank in the crawl space & buy the largest one that will fit. The cabin will be used 3-4 days/week, so not sure I will be using a lot of water-50g/day sounds like a lot. The well might be deep, around 400' but the static level will hopefully be around 150' (based on the neighbors' wells). I am looking at the Grundfos because they are supposed to produce a soft start and not draw a lot of power initially.

[PVCabin]

I spoke with one of the well drillers today and it is impossible to size the pump without knowing the specifics of the well (makes sense...). He told me to use the generator (Genrec 6kW) to run the pump and store a few days worth of water in a holding tank & then use a 12V DC pump to pressure the water for the cabin. Any thoughts, suggestions? Seems like the least expensive way to run the well pump, otherwise I would probably have to spend an extra thousand or two on a larger solar system just to run the pump.

[Mike90250]

Sounds right to me. I'd still get a genset that can run the pump, and power a plug-in charger for the batteries, as long as you are burning fuel, may as well charge too.

Look in the Boat & RV market for small pressure systems, they may provide up to 2 GPM for a shower.

[PVCabin]

Thanks Mike, I will look into the RV/Marine pumps. I was planning on getting the Generac 6Kw as this is specifically designed for off-grid use and could run the pump and charge the batteries on cloudy/snowy days. I would assume this generator has sufficient power...my solar system will only require about 800W of panels, although still working on the final system requirements. My two biggest power draws were going to be the fridge (getting a Consul propane fridge) and the well pump (will now run off the Gen). Not sure yet about the washer/dryer-may do the Wonder Wash and clothes line for now...

[Mike90250]

Propane Fridge - if you use it more than 5mo of the year, solar works out to be less expensive, than refilling the propane. Must get Energy Star rated fridge, < 400KWH year spec
The extra solar gear pays it off in a couple years.

[Naptown]

If it is that cold there in the winter consider using the Irish Ice box as my mother would call it The front porch. I am also sure you could set up some sort of system that uses cold outside air to keep things cold with a compressor to kick in when it was not cold enough outside. Considering you are getting the least out of the solar in the winter when it is cold this may be an option It could be done with something as simple as a remote bulb thermostat connected into the compressor circuit to lock it out when it is say 20 degrees outside or below. then the refrigerator thermostat would only bring on a fan to circulate from the outside. Now a freezer could be more challenging perhaps a separate small chest freezer?

[SteveC]

We have a SQ Flex installed in our well, half horse. I don't have the spec's handy, but far as I recall, the pump co. that sold me the pump tried to get me to take the non-soft start version. They told me that version had a 60 amp starting surge. No way I wanted to get into that, so I insisted on the soft start. They said the soft start version drew 11 amps surge. I paid about a hundred bucks more for the soft start, very glad I did.

[PVCabin]

Propane Fridge - if you use it more than 5mo of the year, solar works out to be less expensive, than refilling the propane.Must get Energy Star rated fridge, < 400KWH year spec. The extra solar gear pays it off in a couple years.

Hey Mike, thank you for that info...I was only thinking of using propane since the fridge was using up the majority of the solar system. I will be using it year-round, but the compact fridges I was looking at are around the 320kwh/year...or about 870W/day; which would exactly DOUBLE my daily usage. So is it still cheaper to double the solar gear requirement just to run the fridge? I would actually prefer to go this route and not rely on the propane, but seems expensive considering my minimal daily usage...Just a thought.

[PVCabin]

If it is that cold there in the winter consider using the Irish Ice box as my mother would call it The front porch. I am also sure you could set up some sort of system that uses cold outside air to keep things cold with a compressor to kick in when it was not cold enough outside. Considering you are getting the least out of the solar in the winter when it is cold this may be an option It could be done with something as simple as a remote bulb thermostat connected into the compressor circuit to lock it out when it is say 20 degrees outside or below. then the refrigerator thermostat would only bring on a fan to circulate from the outside. Now a freezer could be more challenging perhaps a separate small chest freezer?

In the winter is does get cold, there was not a cloud in the sky today with a relatively warm temperature of 37F, but at night it drops into the teens and occasionally single digits/sometimes negative. I was thinking about the 'Irish Icebox', but there are too many animals up here (rabbits, deer, elk, bears...etc), so not really an option for me. I really like the idea of bringing in the cold air for the fridge during the winter-I will have to research this option as it would certainly work! As far as the freezer, I will try and research a small chest freezer that is energy star rated...

[PVCabin]

We have a SQ Flex installed in our well, half horse. I don't have the spec's handy, but far as I recall, the pump co. that sold me the pump tried to get me to take the non-soft start version. They told me that version had a 60 amp starting surge. No way I wanted to get into that, so I insisted on the soft start. They said the soft start version drew 11 amps surge. I paid about a hundred bucks more for the soft start, very glad I did.

I definitely want to go with the soft start, even if I use the Gen to run the well pump. Do you by chance know the model of the SQ pump and your well info: depth and static water level?

Thank you!

[PVCabin]

Found this article while researching energy efficient refrigerators...Very interesting.

http://mtbest.net/chest_fridge.pdf

[Mike90250]

The chest freezer to a fridge conversion, is well known. I like the thermostat he has rigged up for his kit. But, it needs an odd spot to store it in, a conventional kitchen has no site for it.

A regular size 18CF energy star fridge has many advantages over the mini fridges or the "special solar power fridges". After a couple years, the savings on propane, pays for the extra PV panels used. You can pay now, once, or pay a little bit forever.

[SteveC]

I definitely want to go with the soft start, even if I use the Gen to run the well pump. Do you by chance know the model of the SQ pump and your well info: depth and static water level?

Thank you!

SQEO5 180 is our model. Five gpm.

The drillers hit water at 325 feet, good flow of 5 gpm. However, in our case, it turned out to be a flowing well, so the head begins at the top of the well pipe rather than 325 feet down. The well top is about 100 feet below our cistern, so we call it 100 feet of head.

We are also at 8500 ft. MSL elevation, and that is supposed to lead to derating the efficiency of the pump. I have held a stop watch and a five-gal. bucket up at the cistern and timed the fill...turns out to be as close to 5 gpm as I can tell with that crude but not ridiculous test. So the pump does as rated even up here at this elevation. Helps that it's a flowing well, of course, as the head remains static since the well is producing about what the pump is pumping.

The Grunfos has been in use here for four years; so far, no trouble and it works great. The 11 amp starting surge is no issue for our 2800 w. Outback inverter, nor was it a problem for our old Trace 2500 w. inverter before we replaced it last summer. The Trace is a modified sine wave inverter and that also caused no problems with the pump.

So, in summary, we get 5 gpm from the pump, as rated, and that's with a hundred foot head. The way the pump runs, I think we'd be fine if our head was significantly more than a hundred feet, though I haven't any way to try that.