Will I Need a Battery?

[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

[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.

[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]

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]

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.

[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.

[bob-n]

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

[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.

[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

[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.

[Mike90250]

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

[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.

[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.

[Asterix]

Thanks for all the info. Exactly, I only want the pump to run when the sun's out, and efficiency is not a concern.
The panel is a 100w, 5.5a, 12v. The pump is 12v, 3.8 amp. Don't know about watts. It's manufactured by Whale. Couldn't find specs on their website.

Actually your panel is not 12V, its more like 18.18V to give you a 100W output. As soon as you connect a load the Voltage will of course drop,ergo your Wattage goes down.
Just remember the Voltage and current on all but the newer panels state: Open load Voltage and short circuit current.
With a 40W pump it may work ok on sunny days, its a case of try it out, however if you have a meter, then use a battery and check real world statistics for the pump. Then you will know if the panel is suitable.

40W is a large pump with high flow rate, so it may be worth checking that you need a pump of that size.

[Asterix]

I think anything designed for solar hydroponics is better than what I looked into, but didn't build, with a voltage regulator or buck board instead of batteries.

Amazon has 8V - 40V tp 13.8 VDC 10 Amp buck converters. This particular buck converter says it can be used for solar. Some of the fine print on other voltage regulators, especially the higher amperage says NOT for solar.

I had thought about using this to run a 1000 GPH pump, 12 VDC, 7 amp bilge pump. It would be part of equipment I hiked in and a buck converter or voltage regulator is much lighter than hiking a battery in. Unfortunately for this project and what I was using it for, a small gas pump was so much more economical and lighter when you thought about hiking two or three fragile solar panels in. Just plugging this cheap bilge pump into a panel, others said it surged in the sunlight, so I'm not sure how long that bilge pump would last.

10 amps is not a lot of power, probably just enough to power the bilge pump and not much more.

It's a shame you can't buy a higher wattage DC regulator designed for solar to take the $1000 battery bank out of the equation for things you'd want to run on DC, but it just does not exist. I've seen a few years ago a company developed one, but seems not to have taken off. So many things can go wrong with that voltage regulator idea.

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.