Will I Need a Battery?

[chrisski]

I would just use 18650 batteries with suitable charge controllers for the battery bank. Not that much weight compared to lead acid and could be carried to wherever you want. I wouldn't bother with Voltage regulators so much these days as they are power hungry, a buck converter is far more efficient.

I am surprised you cannot find a higher power DC regulator, maybe you are not looking for the correct thing.

A charge controller is a DC regulator, designed to give you a Voltage out which although may vary a little does work well. My Renogy mppt can take a large Voltage in and produces a regulated Voltage out. You don't have to have a large battery, In fact it can be pocket sized if all your intending to do is to use it during daylight.

When I started with solar, my goal was to cook electric. When I started doing the specs on my RV and the panels I laid out, at best I could use an occasional cup of coffee from a one cup coffee maker. I had to really temper my expectations, but I’m sure everyone did.

I then thought a bunch of panels hooked up to a DC stove cooking only in the daytime would be great, but I found no real high wattage DC appliances, and the closest for cooking was a truck drivers crock pot you plug in a cigarette lighter.

I started to look at DC regulators, and the few I found 1000 watts or in excess said not for PV panels, or had a very specific voltage to maintain. I checked Amazon and E-Bay and a few company sites that google led me to.

That’s a quick summary of what I tried.

[LarryJ]

Actually your panel is not 12V, its more like 18.18V to give you a 100W output. .

Do I risk burning up the pump if I use that panel without a charge controller or battery.
I ran a short test when the panel arrived. The flow rate is fine for my purpose.

[Mike90250]

It depends on how robust your pump is, and how much overhead your solar panels have to overvoltage the pump at load power.

[Asterix]

Do I risk burning up the pump if I use that panel without a charge controller or battery.
I ran a short test when the panel arrived. The flow rate is fine for my purpose.

You are looking at 40W @ 12V which gives you a current of 3.33A.

Your solar panel, on a sunny day, will produce this amount under load so it should be fine.

I doubt very much that you could actually draw enough current to harm the pump in any way.

[Asterix]

I started to look at DC regulators, and the few I found 1000 watts or in excess said not for PV panels, or had a very specific voltage to maintain. I checked Amazon and E-Bay and a few company sites that google led me to.

That’s a quick summary of what I tried.

A charge controller is a DC regulator. I tend to think a lot of people get tripped up on what they are calling something, A charge controller is just a DC regulator rated at a certain current.

If someone says not for PV panels, then avoid it like the plague as the ratings are more than likely bogus, or the unit has an unprotected circuit, which also needs to be avoided. A good regulator will never specify what it is to be used on, other than by way of limitations within its spec. As in terms of Voltage Current and input/output loads.

A 1000W device at 12 V would draw 83A and need very thick cables( 8 mm), Plus the fact that a PV panel may only kick out 4A so 25 Solar Panels may do it At 24V you are still talking about 41A and 15 100W panels. Wire thickness around 4 mm

[LarryJ]

You are looking at 40W @ 12V which gives you a current of 3.33A.

Your solar panel, on a sunny day, will produce this amount under load so it should be fine.

I doubt very much that you could actually draw enough current to harm the pump in any way.

Checked it in full sun mid-morning; it put out 22 volts. Was reading 20 volts on overcast sky.

[bob-n]

Are you saying that it delivered 22V into the pump, or 22V open circuit?

[Asterix]

Checked it in full sun mid-morning; it put out 22 volts. Was reading 20 volts on overcast sky.

I will assume that is open circuit Voltage, which is fine once you put a load on it. The figures written on your panel are usually average values for all solar PV's produced, of that type and are usually around an average of 18.5V. So an open circuit Voltages you have shown are of course possible and will vary from panel to panel.

There is also the fact that pump windings have a decent tolerance and are usually rated conservatively as well, so the figures given are again a batch average. Any motor/pump has to withstand the inrush current, which can be quite high, depending on the load of the pump. It needs this high current to get started so the windings of the pump need to have a good safe margin for this high current.

[LarryJ]

I will assume that is open circuit Voltage, which is fine once you put a load on it. The figures written on your panel are usually average values for all solar PV's produced, of that type and are usually around an average of 18.5V. So an open circuit Voltages you have shown are of course possible and will vary from panel to panel.

There is also the fact that pump windings have a decent tolerance and are usually rated conservatively as well, so the figures given are again a batch average. Any motor/pump has to withstand the inrush current, which can be quite high, depending on the load of the pump. It needs this high current to get started so the windings of the pump need to have a good safe margin for this high current.

22v at the MC4 connections on the back of the panel. Nothing is mounted or connected at this point.
My plan is to run it without a battery or charge controller. If the $26.00 pump burns out. I'll add the controller.
Thanks for all your help.

[SunEagle]

22v at the MC4 connections on the back of the panel. Nothing is mounted or connected at this point.
My plan is to run it without a battery or charge controller. If the $26.00 pump burns out. I'll add the controller.
Thanks for all your help.

Just remember that 22V is the Open Voltage or Voc of the panel and it will drop down to the Vmp level (maybe 17 to 18v) once you put a load on the panel.

[LarryJ]

Just remember that 22V is the Open Voltage or Voc of the panel and it will drop down to the Vmp level (maybe 17 to 18v) once you put a load on the panel.

Well, got the panel and a on/off switch installed. The pump lasted about 30 minutes without a charge controller. Can't get it working with a battery. I'll have to implement Plan B noted above.

[SunEagle]

Well, got the panel and a on/off switch installed. The pump lasted about 30 minutes without a charge controller. Can't get it working with a battery. I'll have to implement Plan B noted above.

That is too bad. Let us know if you can get the pump going again.

[Asterix]

Well, got the panel and a on/off switch installed. The pump lasted about 30 minutes without a charge controller. Can't get it working with a battery. I'll have to implement Plan B noted above.

I am very surprised that it should blow your pump. A 12V pump should be able to withstand at least the 18V the solar panel could kick out on a very bright day.

Depends on the battery, put it across a car battery to try it out.

If you just want a solar powered pump, you could use a buck regulator, which you can pick up fairly cheap off ebay or amazon. For a 40W pump you will need to have a unit capable of 3.33A @ 12V

[LarryJ]

I am very surprised that it should blow your pump. A 12V pump should be able to withstand at least the 18V the solar panel could kick out on a very bright day.

Depends on the battery, put it across a car battery to try it out.

If you just want a solar powered pump, you could use a buck regulator, which you can pick up fairly cheap off ebay or amazon. For a 40W pump you will need to have a unit capable of 3.33A @ 12V

Well, the pump stopped working for some reason. Can't say that it blew. Before cutting it open I tested it on two car batteries and it wouldn't spin. It would spin by hand. It's marketed as a "galley" pump, so maybe it's not meant to run continuously for hours. Several days last week it did run continuously for several hours off a car battery. I was testing it to see how it would respond and what the water feature might look like. I ordered another one.
Idealy, I'll find a 12v pump that's designed as a "pond pump".

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[Mike90250]

A galley pump is for pumping water to the kitchen sink in a boat. Usually for just a couple minutes. Something like a Bilge pump, which has an outlet hose connection, and you can dunk the whole thing in the water, is more like what you need