Solar panel and battery

Hi all, I have to make a little project for my studies, since I'm very new in this world I'm in search of any help that you can give me! I want to make circuit where a a solar panel, connected to a charge controller and a battery, could feed a load. If the output of the panel is not enough, I want to use arduino for set-up a switch between the solar panel and another source like AA batteries. After all this, I want to use a raspberry PI, or the YUN version, for make a web page for reporting all the data that I get in the circuit. Since all the circuit is in DC i thought that i could use hall effect sensors for getting data. I'm not sure about the switch, and I don't know how can I handle the charge controller. I'm at the beginning of the work, if someone could help me out in any way that would be great ;D

A solar controller's job is to pretty much switch between solar and battery back up... There is no real extra needed in this as far as I can see?

The measuring of voltage is easy enough with a divider and using the analog pins of the arduino.

The analog pins can take a max of 5V...without knowing the batteries or panel you are using, can not give a divider resistance values.

As you refer to AA batteries, I assume the load is very light?

Weedpharma

If the Solar panel is small enough, and you use AA Nimh batteries, then no charge controller is even needed. Just connect the solar panel to the battery via a diode to block reverse current when there is no sun.

mauried: Just connect the solar panel to the battery via a diode to block reverse current when there is no sun.

And if you get the Arduino to measure the voltage on both sides of the diode it can tell if the solar panel is feeding the battery.

Some sort of voltage regulator might be needed to protect whetever is using the electricity from a very high solar panel voltage.

...R

Thanks to everyone for the answers, I’m close to complete the project.
I can take all the data I need from battery and from the panel, so I can feed my Web page for report the solar circuit status.
Now I have a problem, I want to connect my output to a relè and to the normal 220v home current, so if my battery can’t feed the load I can just switch to the other current and let the panel charge again the battery.
In my mind I just want to connect all stuff, and control the relè with Arduino, but I’m not sure on which component I have to choose.
I appreciate any help you can give me! Thank you!

You want to power your device of solar/battery while there is sufficient charge and switch to 240vac when the charge is low.

For safety, I would be using a plug pack supply rather than switching mains voltage. Modern switchmode supplies draw minimal power on standby.

More information on the load would help us understand what you are doing.

Weedpharma

You may want to use a grid tie inverter if you want to push power back into the normal house voltage, rather than a switching transformer.

If you are referring to AA batteries, then it sounds like you do not have much power from the solar panels. Not enough to switch a relay to run the house voltage...

What are your solar panels rated at?

A charge controller's main job, is to provide charge to the battery(s), while not overcharging (destroying the batteries).

I think OP wants to use house supply to power the load when solar battery is low. Not to feed into the house power.

Weedpharma

[quote author=jack wp link=msg=2481986 date=1447721845] You may want to use a grid tie inverter if you want to push power back into the normal house voltage, rather than a switching transformer.

If you are referring to AA batteries, then it sounds like you do not have much power from the solar panels. Not enough to switch a relay to run the house voltage...

What are your solar panels rated at?

A charge controller's main job, is to provide charge to the battery(s), while not overcharging (destroying the batteries). [/quote]

Thank you for the answer, but like weedpharma said I just want to power the load with the house supply when the solar battery is low.

weedpharma: ... I would be using a plug pack supply rather than switching mains voltage. Modern switchmode supplies draw minimal power on standby...

More information on the load would help us understand what you are doing.

Let me explain the situation. I have my Panel (10W, 12V output) with all his circuit and battery, I use arduino as a sensor, with some voltage divider for get the circuit's data. For the load, I'm using a led headlight and a dimmer, for simulate a variable load. I want to use a sort of switch, controlled by arduino, for use home supply. I don't understand how can I use plug pack supply for that! Maybe I'm just missing something :slightly_frowning_face:

Deusy94: Thank you for the answer, but like weedpharma said I just want to power the load with the house supply when the solar battery is low.

Let me explain the situation. I have my Panel (10W, 12V output) with all his circuit and battery, I use arduino as a sensor, with some voltage divider for get the circuit's data. For the load, I'm using a led headlight and a dimmer, for simulate a variable load. I want to use a sort of switch, controlled by arduino, for use home supply. I don't understand how can I use plug pack supply for that! Maybe I'm just missing something :slightly_frowning_face:

So: you want to light up a light (led). When the sun is shining you want to power the light from a (solar panel, charge controller, battery), but when your arduino detects that the battery is low, you want to power the light from the house current ? You told us your Panel is 10W at 12V. What size is your battery? What power does your light draw? Do you run the light 24/7 ? When you want to power the light from the house voltage, what adapter do you expect to use to get down to 12V ?

If the requirement is simply to use solar power when it is available or else household power a simple solution would be to feed the low voltage DC power from the mains to the Arduino through a diode. When the voltage on the solar side exceeds the voltage from the household power it will provide power and no current will be taken through the diode. No intelligent devices are required.

Something like this

WallWart -------------- ->|- ------------------------------- Solar Panel | Arduino

...R