What measurement photo voltaic water pump do you want?

Photo voltaic water pumps proceed to develop in recognition, and for a great motive — they’ll deal with any water provide venture, from home provide to large-scale irrigation. That stated, the wrong-size photo voltaic water pump can flip a clever funding into an enormous headache.

As a potential photo voltaic water pump purchaser, you might want to familiarize your self with all the required sizing data. Belief us after we say there’s greater than sufficient incentive to take action.

Failure to buy the right measurement pump can lead to pointless return journeys to the shop, delivery returns, and, worst of all, you being left with a pump that can’t fulfill your water calls for.

Let’s take a better have a look at how one can keep away from these nightmare eventualities. 


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Photo voltaic water pump measurement: desk

The next desk highlights the water calls for and corresponding photo voltaic water pumps for various measurement households.

Water wants Amount of water per day Kind of water pump Pump energy (DC) Pump voltage (DC)
Small home (2 folks) 120 gallons (454 liters) Submersible 50W-150W 12V- 30V
Home (household of 4) 300 gallons (1135 liters) Submersible 50W-250W 12V- 30V
Home+ (household of 5 + swimming pool) 450 gallons (1703 liters) Submersible 150W-270W 12V- 30V
Circulation pump for swimming pool 4500 gallons per hour (18m3/hour) Above floor 500W 48V
Agricultural irrigation 5000 gallons per hour (20m3/hour) Submersible 1500W 110V

What measurement photo voltaic water pump do you want?

To find out the dimensions of the photo voltaic water pump you require, perform the next:

  • Minimal pumping stream: Calculate the minimal pumping stream out of your day by day water wants.
  • Whole dynamic head: Calculate the full dynamic head from the depth of the nicely and the space from the water supply to your storage cistern or home.
  • Right photo voltaic water pump: Supply the right pump with matching specs.
Solar water pump diagram.
Photo voltaic water pump diagram.
Supply: researchgate

1. Calculate the minimal pumping stream

To calculate your minimal pumping stream, you will need to estimate your water wants.

Let’s assume your photo voltaic pump will function throughout peak sunshine hours — between 9 AM and three PM (360 minutes). In case your family consumes 300 gallons day by day, that’s 0.83 gallons per minute (300 gallons/360 minutes=0.83).

Variable energy

As it’s named, a photo voltaic water pump wants photo voltaic panels to perform. Photo voltaic panels are variable energy turbines — their energy output varies all through the day and 12 months. Consequently, a photo voltaic water pump’s water manufacturing additionally varies.

This will turn into problematic as your water wants are comparatively steady, although there may be typically a rise throughout the summer season months.

The most typical answer to a variable water provide is to retailer water in a cistern. As a rule of thumb, we advocate a 7-day water storage capability.

A household of 4 utilizing 300 gallons day by day would wish a cistern of 2100 gallons.

2. Calculate the full dynamic head

To accurately measurement your photo voltaic water pump, you will need to think about the depth of your nicely and the friction from the pipes that slows the water stream. In different phrases: the deeper your nicely and the longer your pipes, the larger your water pump have to be.

Pump producers generally use the full dynamic head (TDH) to calculate the impression of friction loss on the water stream.

TDH = Static head + Friction loss

To calculate the full dynamic head, you’ll want the next:

  • Static head: That is the space between your nicely’s water degree and the highest of your water tank.
  • Friction loss: This pertains to your pipe’s sort, size, and diameter.

Be aware to our readers: Estimate your friction loss right here.


Your nicely is at a depth of 70ft. Your cistern is on the similar degree, positioned 200ft away out of your photo voltaic pump. Subsequently, the TDH is:

 70 + 0.14 = 70.14 ft

On this configuration, you’ll need to search for a photo voltaic pump with a minimal stream price of 0.83 gal/min and a dynamic head of 70.14ft.

3. Discover a matching photo voltaic pump

You possibly can choose the right water pump with the minimal pumping stream price and the full dynamic head.

Photo voltaic water pumps are specifically designed to work at variable energy. You’ll have to take a look at their efficiency chart exhibiting the water stream within the pump energy and the dynamic head perform.

With this configuration, you’ll need to search for a photo voltaic pump with a minimal stream price of 0.83 gal/min and a dynamic head of 70.14ft.

Solar water pump flow chart.
Photo voltaic water pump stream chart.

On this instance, the 12V DC water pump meets the water provide necessities (70ft, 0.83 gal/min) with an influence of solely 24W (2.0Ampsx12V=24W).

What measurement photo voltaic system does your water pump want?

Now it’s time to measurement your photo voltaic system. Doing so will assist you present your pump with the required quantity of energy.

First, collect the next info:

  • Pump energy at minimal water stream and complete dynamic head
  •  Photo voltaic panel hourly energy profile

The stream chart within the earlier part indicated that the pump is able to assembly the water provide necessities — 0.83gal/min, complete head of 70.14ft — at an influence of 24W.

With a 30% further energy margin, the photo voltaic panel ought to provide a minimum of 32W between 9 AM and three PM. Now, it’s time to pick a photo voltaic panel that may fulfill this energy requirement.

To do that, you will need to extract a photo voltaic panel’s hourly energy profile at your nicely’s location. You could find this info utilizing the photo voltaic calculator from International Photo voltaic Atlas.

Enter your location and the photo voltaic panel’s energy, and the calculator will present an entire report of your potential photo voltaic manufacturing.

On this instance, we examined a 100W photo voltaic panel in San Francisco. This photo voltaic panel will fulfill your necessities from 9 AM to three PM, even all through winter. 

The hourly power profile of a 100W solar panel in San Francisco, California.
The hourly energy profile of a 100W photo voltaic panel in San Francisco, California.
Supply: International Photo voltaic Atlas

In conclusion, to provide water for a household of 4 within the San Francisco space, you’ll solely want one 100W photo voltaic panel coupled with a 12V photo voltaic water pump.

Do water pumps use a number of electrical energy?

A DC photo voltaic water pump makes use of 3 times much less electrical energy than an AC water pump of the identical pumping capability.

Naturally, the deeper your water nicely, the extra electrical energy your water pump will use.

Within the earlier part, we demonstrated that for a household of 4 with a 70ft nicely, the water pump makes use of 24W for six hours. That’s solely 144Wh per day (24Wx6hours). As compared, a family-size fridge wants about 1200Wh per day.

Ultimate ideas

In abstract:

  • To amass the right measurement photo voltaic water pump, you will need to estimate your minimal water stream and the water elevation (dynamic head) from the underside of your nicely to your own home or cistern.
  • By estimating your location’s hourly energy output profile, you’ll be able to decide the quantity of solar energy essential to run your water pump.
  • DC water pumps don’t use a number of electrical energy. 
  • The pump makes use of 8 instances much less electrical energy than a fridge to meet a household of 4’s day by day wants,

In case you have any additional questions, please attain out to us within the feedback part or comply with us on Twitter.

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