Advice for simple set up for solar pump

[Crossy]

Your panel will rarely, if ever, actually achieve its rated power. The "300W" is the output when receiving 1000W/m² of solar energy (mid-day on a perfect day near the equator). Of course the output also varies during the day as the sun moves (OK we move really).

 

This is the output from our 5.8kW array (8*300W and 10*340W panels) on the best day this year (it's actually the inverter output so there is a little inefficiency).

 

 

Note that we never get much more than 80% of rated output and that's with dual MPPT controllers.

 

A slightly less wonderful (and more typical) day looks like this.

 

 

The nice thing about DC motors (both brushed and brushless) is that they adapt to the available power, less power and they simply run slower, but they still run and produce useful output.

 

I would try one panel directly coupled to the pump and see how it goes, if you're not getting enough water add another panel in parallel.

 

Check the voltage at the pump at mid-day on a nice sunny day just to ensure you're not over-volting it.

 

[mixed]

Thanks Crossy, I thought it might be something like that. Do you think the surface pump I listed will work ok on a well. Water depth is 1m to 4m depending on the time of year. I suppose I should also buy a voltage tester. Will a cheap one be adequate?

[Crossy]

The surface pump Hmax is 15m, although it doesn't list a maximum suction I would think 4m would be OK.

 

A cheap digital meter from Tesco would be more than adequate for what you want to do.

  

[sometimewoodworker]

On 11/18/2020 at 12:42 PM, Crossy said:

The surface pump Hmax is 15m, although it doesn't list a maximum suction I would think 4m would be OK.

 

A cheap digital meter from Tesco would be more than adequate for what you want to do.

  

Most pumps list a 7~8 metre maximum suction depth but realistically you should reduce that by around 3 metres for general use so the 4 metre distance should be OK. Don’t forget a foot valve to allow for water retention  and don’t forget that very few pumps are self priming and the suction is usually only for water. 
 

I am excluding jet pumps as they don’t use suction.

[mixed]

Thanks for all the advice. I've bought the panel, charge controller board, small battery and pump. Below I've attached a pic of the control board. I am a little confused about connecting the pump (and other appliances). The area circled is the output. Should I just connect the pump to this? If so what if I want to connect other appliances? All the tutorial videos I watched used fuses before going out to appliances, so I'm a little confused.

[Crossy]

9 minutes ago, mixed said:

Should I just connect the pump to this?

 

Yes, any further appliances connect to the same terminals.

[mixed]

6 minutes ago, Crossy said:

 

Yes, any further appliances connect to the same terminals.

Thanks. Do I need a fuse box? Surely I will need another fitting for multiple appliances?

[Crossy]

9 minutes ago, mixed said:

Thanks. Do I need a fuse box? Surely I will need another fitting for multiple appliances?

 

Just hook everything + to +, - to - and it's good to go.

 

Fuses, entirely up to you, the fuse boxes sold for in-car entertainment systems would do the job very nicely.

 

Something like this:-

https://www.lazada.co.th/products/6-way-blade-fuse-box-with-led-indicator-fuse-block-for-car-boat-marine-caravan-12v-24v-i1818346633-s5452372378.html

 

[mixed]

The cheap solar charger I was using blew up, on top of the unit it says "Max input 260w", however I'd connected it to a 340w panel. The controller is rated for 20A, from what I read this should a 20A "charge controller is safe for use with up to 20-amp or 480-Watt from a solar array"

 

So I bought a new controller, supposedly MPPT. It is rated for 30A, with a Max input of 370w. The only problem is the LCD goes blank when I turn on the panel. When I turn the panel off the LCD briefly shows '24v' as the input from the panel, so my guess is the voltage is too high. The unit isn't working as per the manual, which doesn't make complete sense.

 

When buying online I see the same pictures of various products at a range of prices. It's not clear if it's the same product or just looks the same, but has higher specs. Lengths and sizes are often not listed. Most of the solar controllers don't list max input. The prices vary a lot, but even the mid priced ones have a max of less than 400w. Would this mean I'd have to have a new controller for each panel?

 

[Crossy]

Can you post a link to your new controller?

 

You probably need to connect it to the battery before the panel so it can determine the system voltage and the battery needs to be at 12V or whatever you are using.

 

Where are you looking at charge controllers?

 

Note that the "20A" is invariably the output current, so at 12V that would be 240W which would explain the 260W max.

[mixed]

I connected the battery before the the panel. When I turn on the panel the voltage climbs and then the LCD goes blank. I think the voltage is too high, but I can't change it. The pic shows the controller just before the LCD goes blank.

 

[Crossy]

I wonder if it's shutting down because the battery is full, what happens if you run the pump?

 

How much was the controller?

[mixed]

The pump is not currently connected, there's a tiny light plugged in, turning it on changes nothing. I'm still sorting out wiring for the pump, so I've been removing the battery from the system to use it. For this reason I doubt the battery is full.

 

The charge controller was only B320, I checked the comments today, one customer is saying it's not MPPT. I realize it's cheap and don't expect a lot, but not working at all and useless manuals are frustrating. I don't want to rush to buy top quality until I understand more. Also even the expensive controllers are only around 40A. If I have a system over 1,000w would I need several controllers?

[maxpower]

56 minutes ago, mixed said:

I connected the battery before the the panel. When I turn on the panel the voltage climbs and then the LCD goes blank. I think the voltage is too high, but I can't change it. The pic shows the controller just before the LCD goes blank.

 

 

Sorry to break the bad news but that is not a MPPT controller. 

These $10 PWM controllers will almost certainly call it a day if expected to take the lions share of pump start current using available solar power and a low capacity battery.

 

One would normally let the charge controller charge a battery then unleash the stored amps on the pumping operation. Direct pump operation from solar panels requires a lot more thought. Brushless DC motor control is a common method.

 

For battery charging and load, there should be at least some basic power matching with the solar panels. For PWM charging of a 12V battery I would expect it to be looking for around 18V from the panel.

 

[mixed]

5 minutes ago, maxpower said:

One would normally let the charge controller charge a battery then unleash the stored amps on the pumping operation. 

 

This is the what I've been doing, disconnecting the battery and using it on a 180w pump.

 

Now the controller is not cutting out, below is a pic. Could this be due to less sun hitting the panel? After fiddling with the switches it went back to PV OFF

[maxpower]

2 minutes ago, mixed said:

This is the what I've been doing, disconnecting the battery and using it on a 180w pump.

 

Now the controller is not cutting out, below is a pic. Could this be due to less sun hitting the panel? After fiddling with the switches it went back to PV OFF

 

What is the final panel voltage

[maxpower]

I found the video below that shows how to operate a 12V pump with cheap PWM charge controller and battery. Note the solar panel power point voltage is around 18V (important). Charging would be improved by adding a identical panel in parallel.

 

 

[mixed]

Just now, maxpower said:

 

What is the final panel voltage

I'm not 100% sure what you mean, but will try to answer. The specs say the panel's 'Maximum power voltage is 37.3'. At times the controller was showing 30v from the panel, other times the LCD switched off when it hit 15v.

[mixed]

2 minutes ago, maxpower said:

I found the video below that shows how to operate a 12V pump with cheap PWM charge controller and battery. Note the solar panel power point voltage is around 18V (important). Charging would be improved by adding a identical panel in parallel.

 

 

Thanks Max, the problem isn't getting the pump to work, but to get the controller to work.

[maxpower]

11 minutes ago, mixed said:

I'm not 100% sure what you mean, but will try to answer. The specs say the panel's 'Maximum power voltage is 37.3'. At times the controller was showing 30v from the panel, other times the LCD switched off when it hit 15v.

 

Below are the instructions supplied with many of the 12V/24V PWM controllers from China. Note the panel voltage for a 12V battery.

 

[mixed]

The max solar input for 12v is listed as 23v. At times the controller was showing 30v, I tried to bring it down but couldn't get it below 25v (it would go back up to 30). I'm wondering if it's mistakenly reading the battery as 24v?

[maxpower]

18 minutes ago, mixed said:

The max solar input for 12v is listed as 23v. At times the controller was showing 30v, I tried to bring it down but couldn't get it below 25v (it would go back up to 30). I'm wondering if it's mistakenly reading the battery as 24v?

 

These controllers adjust their operating parameters from battery voltage applied and then expect to see a valid solar voltage to match. I have no idea how the PWM handles over voltage from the solar side. My guess is it goes out of range.

 

Your panel voltage exceeds the max value required by the charge controller.

[mixed]

22 minutes ago, maxpower said:

Your panel voltage exceeds the max value required by the charge controller.

If you're correct then is the controller only suitable for a very small panel? So what type of controller do I need? I only have a single panel. The listing selling controllers rarely states their operating parameters.

 

The other cheaper controller I had was OK until I accidentally turned off the battery side and it smoked.

[Crossy]

You have a 330W panel.

 

If you have a real MPPT controller driving a 12V battery 330W = 28A so you need a >30A charge controller. But you must check the max input voltage, most of these small controllers are less than the output of a 330W panel!!

 

This unit would work, but it's not particularly cheap

https://www.lazada.co.th/products/powmr-solar-charge-controller-mppt-60a-12243648v-i1605658010-s4385720359.html

that said, it does have enough oomph for future expansion.

 

OR

 

You could just get another PWM controller like the first and not turn off the battery.

[mixed]

Today the controller seems to be working fine, sending around 17v to the battery.

 

Crossy, is that a particularly good MPPT for the price? There are many around at varying prices, I will update eventually, just need to understand a bit more.

[Crossy]

13 minutes ago, mixed said:

Today the controller seems to be working fine, sending around 17v to the battery.

 

Crossy, is that a particularly good MPPT for the price? There are many around at varying prices, I will update eventually, just need to understand a bit more.

 

It could be pulling the panel voltage down so it's inside what the controller likes.

 

The MPPT I linked to is the lowest cost unit I found that can handle the voltage of the 330W panel.

 

 

 

[maxpower]

1 hour ago, mixed said:

Today the controller seems to be working fine, sending around 17v to the battery.

 

17V to a 12V battery ?

[Crossy]

55 minutes ago, maxpower said:

17V to a 12V battery ?

 

Missed that, if it wasn't shot before ...

 

[mixed]

So it may have ruined the battery?

[mixed]

Thanks for your help, if I could just clarify a few things:

17v to a 12v battery is too much and will damage the battery?

Do I need to buy an expensive controller to handle my 330w panel?

What parameters should I look at in a controller?

 

Please let me know if you need more info from me. As I've said earlier, I'm very new to this.

 

How do I know a particular controller will handle my panel? The info when purchasing is limited and sometimes just wrong. The manuals are written in Chinese style English which doesn't give the full story.

 

Crossy: The controller you suggested is more than 10 times the cost of a cheap one. Is this due to the 330w panel? And what if I add other panels? That unit is only rated for 740w, which would be 2 panels. Would I need to add another unit for every two panels?

 

Is an MPPT really necessary here in Thailand?

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