24v pump and panel compatibility

[et_99]

Hi I have two of these panels

https://www.energymatters.com.au/bp-solar-panel-80watt-12volt-polycrystalline-p-18.html

And wanted to know if it would be a good idea (sufficient) to run this pump directly from the panels with no battery at all

https://www.amazon.com/gp/aw/d/B015QRXWA6/ref=psdcmw_3226975011_t1_B07SCP3PBM

I'll be pumping water into a storage tank which will then gravity feed a soaker hose I have for my garden. I may put a battery timer on it so it will only run thirty minutes per day (noon to 1230).

Thoughts???

[SunEagle]

Hello et_99 and welcome to Solar Panel Talk

After looking at that pump, it mentions it will work using both solar panels and a 24v battery although there was a picture with the pump powered directly from solar panels so I am not sure what you really need.

If it was me I would include a battery system and charge controller because the sun doesn't shine every day and you will not be able to pump on those cloudy days without a battery system.

[Ampster]

.........
If it was me I would include a battery system and charge controller because the sun doesn't shine every day and you will not be able to pump on those cloudy days without a battery system.

Here is an alternative that might be less expensive than batteries and a charge controller. Instead of storing that energy in a battery, buy a bigger tank and put a timer on the drip hose for cloudy days.

[et_99]

Thanks for the suggestions.
I actually already have a Toro zero pressure water timer. It's specifically for gravity fed applications.

I don't want to get into battery storage and such so if it's cloudy then the garden just won't get any water that day I guess.
Can't control everything about nature.

[J.P.M.]

Thanks for the suggestions.
I actually already have a Toro zero pressure water timer. It's specifically for gravity fed applications.

Then get an elevated tank and do with PV what's been done for 100+ years with wind power - elevated storage.

[SunEagle]

Here is an alternative that might be less expensive than batteries and a charge controller. Instead of storing that energy in a battery, buy a bigger tank and put a timer on the drip hose for cloudy days.

Yep. If the OP doesn't need to pump every day, then just the solar panels (if they can handle the voltage dip) should be enough.

[Ampster]

Yep. If the OP doesn't need to pump every day, then just the solar panels (if they can handle the voltage dip) should be enough.

A long time ago I bought a device that ran a 12v attic fan off a small solar panel. It was some kind of DC to DC converter that made sure the motor got the right voltage or Amps. Maybe that is built into his pump if it showed it running off solar.

[Ampster]

Then get an elevated tank and do with PV what's been done for 100+ years with wind power - elevated storage.

Yes elevating the tank will get him more pressure than his existing gravity system.

[SunEagle]

A long time ago I bought a device that ran a 12v attic fan off a small solar panel. It was some kind of DC to DC converter that made sure the motor got the right voltage or Amps. Maybe that is built into his pump if it showed it running off solar.

I have a solar fan that works directly from a 10watt panel. It was designed that way.

I believe this pump will also work the same way but you still need to match up the "load" with the solar pv equipment. The advertisement did not go into detail concerning what the panel wattage or Vmp needs to be to properly run the pump. Those 12V panels have a Vmp = 17.6V and are rated 80watts.

Will two of them wired in series be correct to run this 24V pump?

[Ampster]

........
Will two of them wired in series be correct to run this 24V pump?

I presume so if the converter is in the pump. I just read the specs and it says it has a 200 ft lift. It does draw 4 Amps and that.is the question whether 80 Watt panels can provide that unless perfectly aligned to the sun. A workaround might be put the panels in parallel but he might only get 100 ft of lift.

[SunEagle]

I presume so if the converter is in the pump. I just read the specs and it says it has a 200 ft lift. It does draw 4 Amps and that.is the question whether 80 Watt panels can provide that unless perfectly aligned to the sun. A workaround might be put the panels in parallel but he might only get 100 ft of lift.

Parallel panels will only provide less than 18V for a 24V pump. I doubt it will work well.

[Ampster]

Parallel panels will only provide less than 18V for a 24V pump. I doubt it will work well.

The spec sheet says at 12 volts it will work but at half the pressure. So the question for the OP is how high does he need to pump. I only suggested parallel as a fallback option if he can't get enough Amps at 24 volts from those 80 Watt panels. One question is whether the Watt rating is based on nominal 12v or 18v.

[littleharbor]

An LCB (linear current booster) would definitely help with PV direct pumping . Problem is they are so expensive.

[Mike90250]

In theory, it could work
Your panels, 80w @ 17.6v gives 4.5A on paper, in real life, expect no more than 80% of nameplate = 3.6A only at noon, when aimed correctly