A solar panel generates electricity when it is exposed to sunlight. If you only need this electricity during daylight hours, is there any need to hook up a battery to your solar panel controller, or can you use it without a battery?
Here are some aspects of how charge controllers operate and whether a battery is a requirement or not.
- Why can’t you use electricity directly from a solar panel?
- What does a solar panel controller do?
- Does a charge controller need a battery?
- How can you use a solar panel without a battery?
Solar batteries are the most expensive components in a solar system. The cost of these batteries can be prohibitive to many people exploring the benefits of this energy source.
If you only need your solar system to provide electricity in daylight hours, can you do without a battery? You can, but you need different equipment connected to your panel.
Do You Need A Battery With A Solar Controller?
In most off-grid solar system designs, you will almost always see at least 4 components to the system. They are the solar panel itself, connected to a charger controller or solar controller.
In turn, the solar controller has a battery connected to it and outputs to the system load devices, which are the electricity consumers in the equation.
As we have already discussed, the batteries are the most expensive items compared to the other components in the system.
If your solar power needs do not require stored energy, can you simply do without the battery and connect the load to the solar controller?
It may seem like a straightforward solution to simply not connect a battery, but this thinking does not consider how a solar controller works.
Solar Panel Electricity Is Unstable
The electricity produced by a solar panel is not a constant supply at the rated metrics of the solar panel. Both the voltage and the current generated by the solar panel can vary dramatically throughout the day.
The solar panel will only produce its full rated capacity when in direct sunlight. If clouds pass in front of the sun or a shadow falls across a portion of the solar panel, its output will drop.
Likewise, temperature and flaws in the PV cells’ manufacture cause the energy production to fluctuate.
This fluctuating output level from a solar panel is a problem because most of our requirements for electricity require a steady flow at a constant level to be useful and prevent damage to the devices connected to the electricity source.
This fluctuation in the power levels is called noise or dirty power because the output is not linear or constant. This is where the role of the charge controller comes in.
What Is The Role Of The Solar Controller?
With the erratic solar panel energy production, another component must eliminate the noise and clean up the output into a usable power source.
This cleaning up of the solar panel energy output is part of the function of the solar controller. The solar controller regulates power coming in from the panel, distributing the energy to the load and charging the battery.
Many people think that simply leaving the battery out of the equation will allow the solar controller to only supply energy to the load.
Most solar controllers are not designed to work this way. Some solar controllers will simply not function at all without a voltage across their battery terminals.
With others, connecting a solar panel array to the controller without a battery as a reference charge will fry the circuitry of the controller.
The solar controller is an electronic device that needs clean power to energize its own circuits to function. Most solar controllers obtain this power from the battery connected to the solar system.
The power from the solar panel is too dirty to power the solar controller directly.
The battery also provides a reference voltage to the controller to regulate power from the panel and distribute a portion to the battery and a portion to the load. The controller monitors the battery’s charge and will cut off power to the battery to prevent overcharging.
If no battery is connected, there is no reference voltage, and all the power generated by the panel can be directed to the load. This could damage circuits in devices connected to the load output of the solar controller.
Some solar controllers are designed with their own internal battery and can be connected to a solar panel and electrical load without a battery in the circuit.
There are very few controllers designed to operate this way, so you would need to check the specifications of your controller before connecting it up in this configuration.
How To Use A Solar Panel With No Battery
There is a way to utilize the electricity from a solar panel without a battery, but in this case, you cannot use a solar controller either.
You need a different device called a DC-to-DC converter. This device must be rated to the maximum output voltage of the solar panel and then step down to your required output voltage.
For example, if your panel outputs 48-volts and your device requires 12-volt power, you need a DC-to-DC converter that can accept a 48-volt input and deliver a 12-volt output.
An inverter could be connected to the 12-volt output to produce 120-volts AC or 240-volts AC if your devices require this power format.
The problem with this configuration is that the system will only operate if the panel is operating at maximum capacity to generate the 48-volt output.
If the production of the panel drops due to low light or temperature considerations, the DC-to-DC converter will shut off, and no power will be output.
This type of system would work if you only need to power non-critical appliances during the brightest times of the day. For example, a 12-volt pump is used to fill a water tank during the day so that livestock can be watered.
Excluding a battery from your solar system is an inefficient use of your solar panels and limits the usefulness of your solar system in general.
While it is possible to use solar panels without a battery, you will get a better return on the value of the equipment if you maximize their output for your application.
Even if you do not need a battery, it may be worth installing a single battery to get the solar controller to operate correctly and limit the risk of damage to any equipment.