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Solar Water Pumping

**Note: We usually don't recommend replacing existing grid powered pumps with solar. Solar pumps are best used when grid power is too far away and too expensive. If you want to go green and go solar, we recommend adding solar panels to your home and grid-tie them to your electric company. You will get the most "bang for your buck" in today's solar marketplace.

We actually got our start in solar with solar water pumps. 1988 to 1990 in Morocco, we installed 14 village sized solar pumping systems and 2 wind pumping systems. As important as electricity may seem, water is essential to life. Bringing life giving water from under the ground using only the power of the sun or wind is very rewarding. It has also been full of trials and tribulations. We have installed, pulled and reinstalled enough pumps to learn.
Many solar pumps are available on today's market, but we are very conservative in what we recommend, sell, and service. Because water is so important, we are not willing to gamble with unreliable products on our customers' lives. While efficiency is important, reliability is foremost. Unfortunately, a more reliable pump is less efficient and vice versa.

Existing Well and Pump? Please scroll down this page to the checklist.

What SolarRay needs to know to help get you started with solar PV water pumping:

1. What is your water source?

Obviously, this depends on your site. If considering a well, check with neighbors to find out how deep other wells in the area are. Here are the choices:

Rain Catch Cistern: Low cost, rain water itself is very soft (low in minerals), & environmentally friendly. Downside, is that you must haul water when it doesn't rain (very environmentally unfriendly), Depending on roof type,etc. everything nasty ends up washing into the cistern. Water must be treated for drinking.
Shallow Well, Spring: wells under 20 ft deep and springs can be excellent sources, but be careful that surface water can't wash in and contaminate the water. Consider water treatment for drinking.
Medium depth Well: for wells up to 200 ft deep, many pump choices are available. With modern casings and well caps, contamination is rarely a problem.
Deep Well: for wells 200 ft to 450 ft, the pump choices go down, while the cost of the well and the pump system can exceed $10,000. Contamination is rarely a problem with the well itself.
Very Deep Well: for wells over 450 ft, you have fewer choices still. Well drilling & pump costs combined can exceed $20,000. Contamination is rarely a problem with the well itself.

2. What is the water for?

Residential: domestic water supply provides water to faucets at sinks and bath, etc. throughout the house. Usually best to power pump from the house solar power system.

Livestock or irrigation: water is pumped to an open stock tank for animals or to gardens, etc.

Specialty use: this includes fountain pumps, floor heating circulator pumps, and pumps for solar hot water systems.

3. Which Power Sources?

**Note: We usually don't recommend replacing existing grid powered pumps with solar. Solar pumps are best used when grid power is too far away and too expensive. If you want to go green and go solar, we recommend adding solar panels to your home and grid-tie them to your electric company. You will get the most "bang for your buck" in today's solar marketplace.

Solar Direct (DC): Most DC pumps can be powered directly from the solar modules (usually with a controller), this method is known as array direct. For stand alone systems like irrigation & livestock , or if the well is more than 500 ft from other power sources, this is the best.

Battery powered (AC or DC): We usually recommend running pumps from the main solar system of the house. Water can be pumped day or night, and all solar panels are combined into one main house power system. DC pumps use less power (sometimes 1/4 of an AC model), and don't require an inverter. Unfortunately, they are not as reliable. AC pumps use more power, require a large inverter and batteries to start, but are reliable. They are also a good choice if running longer distances (over 100 ft).

Generator powered (AC): For very deep wells, some customers use a conventional AC submersible pump and start the generator once a week to fill a cistern. Obviously this not the most elegant or sustainable method, but it is simple and reasonably reliable, especially for very deep wells.

4. What Pump Type?

A plethora of pump types exist, but for simplicity, we will divide them into these main categories:

Submersible Pump: This type of pump is water proof and is submerged in the water. They are usually more expensive. All electrical connections and motor are submerged as well. Examples: Grundfos SQ pump (AC), Dankoff ETA pump DC, fountain pump.

Surface Pump: are not waterproof. They must be located in weatherproof area near the water level, usually a pump pit or pump house. All electrical parts are located away from the water. If the pump is too high above the water level, these pumps will have suction problems that can make the system unreliable or damage the pump. (See suction head & cavatation)
Examples: Shurflo pressure pump, Dankoff Flowlight pressure pump, hot water circulator.

Jack Pump: is actually a mixture of the 2 types. The motor, gears, & electrical are on the surface, but move a shaft (sucker rod) that attaches to the pump which is submerged. Good for very deep wells.
Example: Solamotor Jack Pump

Existing Pump: Get us the specs, usually we recommend you should keep it, and power it with a grid tied back up system.

5. Cisterns , Pressure tanks, & Water Treatment

If using rain catch or a low flow DC well pump, you will need a cistern, an un-pressurized storage tank. A pressure pump then takes the water and pressurizes it in a pressure tank for regular use at the faucets in the house. The pressure tank holds 10 to 40 gallons of water against an air filled bladder that pushes(pressurizes) the water to the faucet. When the pressure drops, a pressure switch turns the pump on to recharge the tank. This system maintains steady (city) water pressure and keeps the pump from having to turn on every time someone washes their hands.
Gravity feed: Sometimes the cistern can be located on a hill above the house and the water flows by gravity to the faucets. Typically it needs to be at least 20 ft higher for adequate pressure, but this avoids needing a pressure pump and pressure tank.
Water Treatment: The problem with cisterns whether they are open top or sealed, underground, plastic, steel, or concrete, is that they can become contaminated with airborne fecal bacteria. If you do decide to use a cistern, you need to treat the water with chlorine on a regular basis, & filter it with a 0.5 micron filter before drinking. An easy solution for those not wanting to chlorinate is to buy 5 gal bottles of drinking water, and use the cistern water for irrigation and washing. Air bubbling systems can help maintain healthy cistern water by encouraging aerobic bacteria. Anaerobic bacteria thrive without air, and can cause the water to "go septic".
Pressure tanks store water without exposure to contaminates, so if clean water goes into the system, clean water comes out. For domestic water supply, we recommend a sealed well ( get the water tested to confirm purity) with a large enough pump(usually AC) and power system to run directly into a pressure tank.

Make your choice:

Residential ( battery powered from house unless noted)
Water Source
depth to water
DC pressure pump
AC Submersible
DC submersible
DC Jack Pump
Cistern
0 to 5 ft.
Best
OK with deep cistern, or long wire run
NO
Not recommended
Spring or shallow well
5 to 20 ft.
OK if pump is placed within 5 ft of water level
Best, use with inverter & transformer, pump direct to pressure tank
OK
Not recommended
Medium well
20 to 200 ft.
NO
Best, use with inverter & transformer, pump direct to pressure tank
OK
Not recommended
Deep well
200 to 450 ft
May be needed as 2nd pump to pressurize water from cistern
Best, use with inverter & transformer, pump direct to pressure tank
OK with 2nd pressure pump
Not recommended
Very deep well
450 to 1200 ft
May be needed as 2nd pump to pressurize water from cistern
Use generator, or multiple inverters
NO
Nood if pumping to cistern

 

Livestock & Irrigation (powered array direct, unless noted)
Water Source
depth to water
DC pressure pump
AC Submersible
DC submersible
DC Jack Pump
Spring or shallow well
5 to 20 ft.
Good if pump is placed within 5 ft of water level
OK if using Grundfos SQFlex submersible array direct
OK
Not recommended
Medium well
20 to 200 ft.
No
OK if using Grundfos SQFlex submersible array direct
OK
Not recommended
Deep well
200 to 450 ft
No
OK if using Grundfos SQFlex submersible array direct
OK
OK for less than 500 gal/ day
Very deep well
450 to 1200 ft
No
Use generator, or multiple inverters with batteries
No
Best

 

Existing Well and Pump?

Please, we need the following information before we can help you.
**Note: We usually don't recommend replacing existing grid powered pumps with solar. Solar pumps are best used when grid power is too far away and too expensive. If you want to go green and go solar, we recommend adding solar panels to your home and grid-tie them to your electric company. You will get the most "bang for your buck" in today's solar marketplace.
1.   Water source
2.   What the water is being used for: household, livestock, irrigation, drip irrigation?
3.   Power source: Electrical power available: Grid power, existing solar system (DC, 120Vac, or 240 VAC), no power at alls
4.   What pump type
5.   Cisterns , Pressure tanks, & Water Treatment
6.   Depth to water
7.   Total water needed per day
8.   Flow rate (gal/ min.)
9.   Total depth of well
10.   Pressure required (or height to storage tank)
11.   Please send us the specs of your existing pump.
     
     
    Download a .doc file with this table.

Please email the answers to these questions back to us so we can better serve you and your pump needs. Email: support@solarray.com

 

Hot water Circulators

Floor heating systems and solar hot water systems need special circulator pumps to move the hot water. They are specially designed for high temperatures, and low pressure. Many off grid homes have been built where the plumber never worked with the solar designer. The results are disastrous. The pumps and controls of the floor heating system drain the power system overnight in times when you need the power the most: the dead of winter! Waking up to a cold house with no power can be avoided however. For small floor heating systems (under 1000 sq. ft) a 10 to 20 watt DC circulator with a regular gas fired hot water heater works well for a fraction of the electrical energy.

For larger homes with separate heating zones and boilers, we recommend using AC circulators (the boiler can overheat if the pump doesn't move enough water). But energy use can still be reduced by using DC thermostats to control the system.

For solar hot water systems, DC circulators can often be run array direct from their own dedicated solar module. These systems avoid many expensive controls, and simply pump when the sun is shining and the solar thermal is heating. In cold climates these systems require glycol to prevent freeze damage. This adds a heat exchanger and additional complexity. Drain back systems protect from freezing by draining the water out at night, but they require much larger AC circulators to operate.

Link to Catalog for Current Listings.

Other Solar Pumping Info: Dankoff Introduction to Solar Pumping: Solar Tracking,
Inverter Sizing for AC Pumps, Cavatation, Adjusting System Pressure, Plumbing Design:
Pipe Sizing Chart, Pressure & Flow Rate Chart, Solar Pump Glossary

Consultation fees for solar pumping will be applied and deducted from pump purchases.