Newcomer Solar Setup (Need Opinions)

[Kondrath]

Hello,

I am trying to setup my first solar circuit, I have read a lot of forums, and advice topics but am not sure I am on the right path with my diagram. Please look at it and let me know of changes I need to include or tips! I've attached the diagram I drew. =)

Here's the rundown if the diagram isn't understandable.
> (12v 60w PV Panel) runs into a (12v 20A PWM Charge Controller) which hooks up to a (12v 20ah/20 hour lead acid battery) & on the load side of the controller I will run the cable into a toggle motion detector 'for when I walk out the patio door' to trigger a photocell switch to determine if it's day/night and if it's day it'll turn on the 12v 19w DC Pond Pump, if it's night it'll turn on the four 12v 3w LED lights, when I return back into the house the motion switch will trigger off the circuit.

Thank you!

 

[svetz]

Welcome to the forums Kondrath!

Take a look at this thread for some example math and options on pumps for ponds. Hopefully it'll help, if not feel free to ask questions.

As to the wire gauge, it depends on amps and distance, see the FAQ for example math.

 

[DASH]

I don't know why you are using the Load Circuit off of the PWM. I would expect the wiring from the Toggle Detect to go to the battery and not the Load Circuit of the PWM, but then I'm not familiar with that PWM nor the Load Circuit ,maybe there's some reason for it.

 

[svetz]

I agree with Dash... take the load off the battery and add a fuse.

 

[FilterGuy]

Hello,

I am trying to setup my first solar circuit, I have read a lot of forums, and advice topics but am not sure I am on the right path with my diagram. Please look at it and let me know of changes I need to include or tips! I've attached the diagram I drew. =)

Here's the rundown if the diagram isn't understandable.
> (12v 60w PV Panel) runs into a (12v 20A PWM Charge Controller) which hooks up to a (12v 20ah/20 hour lead acid battery) & on the load side of the controller I will run the cable into a toggle motion detector 'for when I walk out the patio door' to trigger a photocell switch to determine if it's day/night and if it's day it'll turn on the 12v 19w DC Pond Pump, if it's night it'll turn on the four 12v 3w LED lights, when I return back into the house the motion switch will trigger off the circuit.

Thank you!

Some math on your production vs load vs battery capacity:

Battery Capacity: 12V 20Ah = 12X20= 240AH.
I will assume the lead acid battery is deep discharge and you can take it down to 50% SOC. Therefor, the working battery capacity is 240AH/2= 120AH.

For this discussion I will assume the LEDs run for four hours and the pump will run for four hours.

The four LEDs will use a total of 12W for 12 Hours 12x4 = 48Whr T
The pump needs 19W for 12 hours. 19x4=76Whr.

The total daily load is 76+48=124Whr

Lets assume the Insolation (effective hours of full sunlight) is 5hrs for your location. Your 60W panel will produce ~5*60=300Whr on a sunny day.

Conclusion: Your battery is undersized for the application particularly if you have a few cloudy days. The solar panel may be large enough.

 

[DASH]

Some math on your production vs load vs battery capacity:



Conclusion: Your battery is undersized for the application particularly if you have a few cloudy days. The solar panel may be large enough.

System may work, if the pump only operates during the day, and the LEDS only during the evening, especially when the items will only run when someone is outside. Presumably, at the end of a sunny or near sunny day, the battery will be nearly full to run the Led lights in the evening and enough power to run the pump in the morning before the panel can produce enough electricity to run the pump and charge the battery for the next evening.

 

[FilterGuy]

Can the load output be programed to shut off if the battery voltage gets low? If so, that may be a reason to use the load output.

As it is, the battery size seems marginal enough that having some kind of low voltage disconnect is probably a good idea.

 

[Kondrath]

Welcome to the forums Kondrath!

Take a look at this thread for some example math and options on pumps for ponds. Hopefully it'll help, if not feel free to ask questions.

As to the wire gauge, it depends on amps and distance, see the FAQ for example math.

Hi svetz, thank you for your input. I determined my wire gauge off this DC AWG Chart. My equipment is 'Non Critical' and will measure out the circuit before I purchase the wire to verify if I need 16AWG, 14AWG or 12AWG.

I don't know why you are using the Load Circuit off of the PWM. I would expect the wiring from the Toggle Detect to go to the battery and not the Load Circuit of the PWM, but then I'm not familiar with that PWM nor the Load Circuit ,maybe there's some reason for it.

Hello DASH, I'm brand new at solar and the equipment involved. As I was told, the 'LOAD' terminals on a Charge Controller are what the PV Panel sends energy to 'FIRST' and whatever comes back on the neutral wire goes into the battery. I could be completely wrong however. My thought was if I went outside in the morning when the PV Panel is only outputting....lets say... 10w and my pump requires 19w, that the battery would make up the other 9w from the day prior of charging.

Some math on your production vs load vs battery capacity:

Battery Capacity: 12V 20Ah = 12X20= 240AH.
I will assume the lead acid battery is deep discharge and you can take it down to 50% SOC. Therefor, the working battery capacity is 240AH/2= 120AH.

For this discussion I will assume the LEDs run for four hours and the pump will run for four hours.

The four LEDs will use a total of 12W for 12 Hours 12x4 = 48Whr T
The pump needs 19W for 12 hours. 19x4=76Whr.

The total daily load is 76+48=124Whr

Lets assume the Insolation (effective hours of full sunlight) is 5hrs for your location. Your 60W panel will produce ~5*60=300Whr on a sunny day.

Conclusion: Your battery is undersized for the application particularly if you have a few cloudy days. The solar panel may be large enough.

Hello FilterGuy!, You are correct my battery has a recommended 50% SOC; therefor, my working capacity is 120Wh. It's not a deep-cycle battery (those have 20% SOC cycles). I took into account 20% efficiency loss as we get 90-100F temperatures daily so my PV Panel output would be around 48w during peak hours which would be around 5 hours = 240Wh daily. The battery can hold a total of 240Wh; however, when my 19w DC pump is running throughout the day that will potentially bring my battery production down to 29Wh x 5 = 145Wh which is what would be required since the battery will never drop below 50% (Thanks to the Charge Controller)

Can the load output be programed to shut off if the battery voltage gets low? If so, that may be a reason to use the load output.

As it is, the battery size seems marginal enough that having some kind of low voltage disconnect is probably a good idea.

When I did some research, the reason we want to use the 'load' terminals on a charge controller is because the controller will determine if your 'load' is about to discharge your battery more than it should. If I hooked up my pump / lights to the battery, I would have to include some type of low-voltage-disconnect switch so my battery wouldn't completely drain. The load terminals on a charge controller aren't meant for anything over the amp rating of the controller, since my load would be around 1.58amps with the pump and 1 amp with the lights, I'm well within my limits.

 

[DASH]

Hello DASH, I'm brand new at solar and the equipment involved. As I was told, the 'LOAD' terminals on a Charge Controller are what the PV Panel sends energy to 'FIRST' and whatever comes back on the neutral wire goes into the battery. I could be completely wrong however. My thought was if I went outside in the morning when the PV Panel is only outputting....lets say... 10w and my pump requires 19w, that the battery would make up the other 9w from the day prior of charging.
[/QUOTE]

Hi Kondrath, I have never used the Load Terminals, so I'm not familar with them. You are correct that the energy gathered from the PV panels will go to the source requiring the electrical energy, and if additional energy is necessary it will come from the battery. If the electrical device has more electricity from the Panels then necessary, the excess will go to the battery.