What size PV panel to run this DC pump for pool heater?

**inetdog** · 09-18-2012, 07:57 PM

Originally posted by mcaimless

I don't know how to calculate the panel size to run this pump. Can someone help me? Here are the specs:

EWP-D50C2465 24V 3 phase water pump with speed controller

Specification

Power: DC12~24V
Current: 3.5A@24V, 1.6A@12V

Do you size the panel to the watts the pump draws? Thanks

You have a choice to make right at the beginning. Do you want to:

1. Run the pump directly off the solar panels whenever there is enough light and not run it at all at other times?
If so, you want to size the panels to a significantly higher wattage than the pump and to have a Voc not above about 28 volts. (24 volts if the pump manufacturer intends to be strict about the 12-24 volts), since a 24 volt battery can produce 28 volts or more while charging or at 100% charge. OR

2. Run the pump based on a timer or other control, using batteries so that it can be operated when the panels are not producing.
In this case, you will need to put in either an MPPT or PWM Charge Controller and wire the pump controls up so that they will shut the pump off when the battery voltage reaches your desired LowVoltageCutOff level (LVCO). The battery capacity at 12 volts must be at least 16AH to deliver the current and will only run 2 hours per day. If you want to run the pump 24 hours straight your battery bank needs to be more like 200 AH. The panels needed to charge that battery bank will then be roughly 600 watts if you will only be using this in the summer, or up to 1200 watts or more if you are in the North and need to use it in winter.

**mcaimless** · 09-18-2012, 08:14 PM

Originally posted by inetdog

You have a choice to make right at the beginning. Do you want to:

1. Run the pump directly off the solar panels whenever there is enough light and not run it at all at other times?
If so, you want to size the panels to a significantly higher wattage than the pump and to have a Voc not above about 28 volts. (24 volts if the pump manufacturer intends to be strict about the 12-24 volts), since a 24 volt battery can produce 28 volts or more while charging or at 100% charge.

I plan to have the pump run when the sun is on the panel. What does the "Power: 84Watt/ 19.2Watt " mean? That I need an 84 (or higher-- how much higher?) watt panel? Also the pump specs state "This is a high quality high temperature DC24V submersible water pump ideal for solar panel. It can be driven direct by solar panel without a regulator. " Does that mean I can just direct wire the pump to the panel? Thanks.

**inetdog** · 09-18-2012, 08:22 PM

Originally posted by mcaimless

I plan to have the pump run when the sun is on the panel. What does the "Power: 84Watt/ 19.2Watt " mean? That I need an 84 (or higher-- how much higher?) watt panel? Also the pump specs state "This is a high quality high temperature DC24V submersible water pump ideal for solar panel. It can be driven direct by solar panel without a regulator. " Does that mean I can just direct wire the pump to the panel? Thanks.

Yes, that is what allows you to use option 1.

If the pump sees 24 volts on its input, it will pump more water, to a higher head. It will see twice the voltage as with 12 volts and will draw twice the current, so it will take 4 times the wattage. It really depends a lot on how much water you need to pump while the sun is shining.
You can either use a roughly 30 watt 12 volt nominal panel and not get the pump to do much at all on even slightly cloudy days or more than an hour or so from noon in winter, or you can use a roughly 120 watt nominal 24 volt panel and get lots of water with full sun and still get some pumping under poorer conditions.

**mcaimless** · 09-18-2012, 08:42 PM

Thank you! Here in Arizona I expect it to pump a good deal of the day when the sun is out. I'll look for a 120 watt 24 volt panel.

What size PV panel to run this DC pump for pool heater?

What size PV panel to run this DC pump for pool heater?

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