solar water pump

Re: solar water pump

For AC pumps, you cannot just drop a 240 VAC pump to 120 VAC... Unless the pump motor is way over sized, simply dropping the voltage will cut the power to ~1/4 ... And then the motor will stall, take too much current, not run properly, and can overheat.

In general, for pumps and other electric systems with long wiring runs, you usually want to run them at as high as voltage as practical to reduce current requirements.

Remembering that Power = Voltage * Current and that a 1 HP 240 Volt motor vs a 1 HP 120 Volt motor will simply require 2x the current if running at one half the voltage (1 HP motor is wired for 240 vs 1 HP motor wired for 120 volts). Simply going with a lower voltage 1 HP motor will not save any power/money--and in fact may cost you more because the wiring has to be twice as heavy (3+ gauge heavier) because of the 2x higher current at lower voltage.

Now--there may be other issues--for example, many off-grid inverters are only available in 120 VAC output--so you need either a second "stacking" inverter or a high voltage step up transformer or some other solution where 120 VAC pump may be more cost effective for a particular installation.

Some of the DC pumps actually vary their output based on the amount of voltage/current available (Grundos pumps for one) and have a Maximum Power Point Tracking system built in to use solar panels (or batteries, or DC genset, or AC genset, or AC utility power).

And you can use VFD (variable frequency drive) on a 3 phase pump to, pretty efficiently, vary the flow/pressure to meet the requirement.

By the way, VFD and other pumps are using 3 phase motors so to avoid brushes/commutators (much longer life). Also some pumps are using permanent magnet motors instead of induction motors to run ~15-20% more efficient too.

By itself, solar power is not usually a less costly method of generating electricity vs utility power... So, looking at your current system and deciding how to conserve power (smaller pump, more efficient pump, low pressure pumping to cistern, small high pressure pump for domestic water, etc.) all help.

Grid Tie Solar Systems (GT inverter + solar panels connected to utility power) is usually the best/cheapest/most reliable method to make solar electricity for the standard grid connected home.

Add new/reconfigured well/pumping system that allows you to conserve power moving water is just icing on the cake.

I am not on a well, and not in the pumping/well business--but looking at your current system (see how many kWH per day you are actually using to pump water), how many gpd you need, pressure (high pressure for house, low pressure irrigation for garden, etc.)--then looking at the solutions and how much money a "Low Energy" system can save you.

Many systems were designed in the day of "cheap energy"--depending on what happens in the future--look at Northern California's peak power rates right now (summer peak can be $0.40-$0.60+ per kWH today) and compare the potential "worst case" power savings with a new/reduced pumping system--perhaps with some sort of solar assist.

-Bill

Re: solar water pump

Marc, yea--many motors can be reconfigured for 120 or 240 VAC use--I was trying to focus on a 1 HP motor at either voltage will cost about the same to run (P=I*V).

Bryan, you might want to look at the whole house kWH meters... They are pretty easy to hook up (clip a transformer on the wire you want to measure the power on)--Should be an AC voltage connection too.

Clip onto the pump circuit and see how my kWH per day you are using... If it is 1/2 your electric bill--then it is certainly worth looking doing something for conservation... And you can figure out if you are pumping water efficiently... I.e., how many gallons per kWH are you pumping with your existing setup for a new setup configured for conservation.

-Bill

Re: solar water pump

Others can probably help you more--As "Moderators", Niel and I are here pretty much for Spam control... Neither of us are associated with NAWS or any other solar businesses.

I will say that look at the total life-cycle costs... Currently you have fairly reasonable power costs so getting a few more years of life from the existing pump/setup may be worth more than electricity saved from a high-tech (and sometimes high cost) pump.

I would monitor the power usage of your major electric appliances. Cooking/Hot water/etc. are probably a major portion of your energy bill.

Mobile homes frequently have limitations that make installing gas appliances more more difficult--And can you even put in a propane tank or not (and is propane viable/natural gas for your location).

If you have A/C (or need humidity control and/or heating)--New high efficiency A/C plus a "desuperheater" for hot water (uses A/C waste heat to heat hot water--Or there are now heat-pump hot water heaters that may be a good deal where electricity is the only reasonable power source)... And there are the mini-split AC (and heat pump) systems too--just cool the room(s) you need during the day.

In any case, I am not convinced that water pumping is a major portion of your bill... At this point pumping should be costing you around $0.20 per hour... Even 5 hours per day, that is only $30 per month.

-Bill