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Solar panels are available in different voltages, but the 12V modules are still the most widely used in RVs and off grid systems. However there are instances wherein 24 volts is the better option as we will show. The good news is you can turn 12V solar panels into 24V easily, and you don’t need a lot of technical know how either.
By joining two 12V solar panels in a series, the voltage increases to 24V, which reduces system cost because it requires a smaller inverter, thinner and shorter wires and fewer batteries to run. This setup works only if the solar panels are 12 volts.
How to Convert 12V Solar Panels into 24V Solar Panels
There are two ways to connect solar panels, by series or parallel configuration. By connecting two or more panels in a series their separate voltages are added up, so two 12V solar panels become 24V.
To join two or more 12V solar panels together, connect the negative panel terminal to the positive terminal of another panel. The series connection increases the voltage but the amperage remains the same. In a parallel connection, the amps are added up but the voltage is not.
Now you have a 24V solar panel which can charge a 12V battery. You use the same steps for any 12V module no matter the size. You can also repeat the series connection for as many solar panels as necessary.
If you want to boost the amperage, join the solar panels in parallel. Just connect the positive terminal of a panel to the positive terminal of the other panel. Do the same with the negative terminals. Now the amps will increase but the voltage will stay the same.
It is possible to connect solar panels in series and parallel. This boosts the voltage and the amps, but it could overload the inverter if not configured properly. A professional installer should handle this so they can evaluate the settings and find the optimum combination.
Important Tips For Solar Panel Series Connections
Configuring solar panels in a series is easy, but there are many ways you can mix and match them.
If you have four 120W 12V solar panels, they can be configured in any of the following:
- 24V at 20A
- 48V at 10A
- 12V at 40A
A series connection will only work if all the solar panels are 12 volts. You cannot connect a 12V 100W solar panel to a 24V 50W solar panel. If you join the two, the system output will be limited to 50 watts.
You cannot join these panels in parallel either. Doing so will cause the panels to overheat and might even cause a solar fire or arcing .
If you want to combine solar panels with different voltages, connect the modules with similar voltages and use a separate charge controller for each set. For example, connect the two 50W panels and then install a charge controller. Next, connect the 12V solar panels and use a different charge controller for it.
Do not join these separate solar panels together. If your inverter has a 24V and 12V input, you can use both panels. Attach the 24V panels to the 24V input and the 12V modules to the 12V terminal.
Not all inverters have this feature. Most of them are for 12 volts or 24 volts. Check your system specs before trying. Only attempt this if the operating instructions specifically says it is possible. With some inverters, you may only be allowed to input either a 12 volt or 24 volt panel, and never at the same time. This is worth keeping in mind if you have a large solar system, say 3kw and need a large battery bank.
24V vs. 12V Solar Systems
Which is better, 12V or 24V solar systems? At first glance 12 volts is the more appealing option since it is less expensive. But 24 volt panels have their benefits too. Which is better depends on what type of solar system you want to use.
12V systems are acceptable if you need only a limited amount of power. But 24V is better for medium to large scale solar systems because it can produce more energy without driving up the component costs.
Let us take a closer look at both 12V and 24V and cases where one will be more suitable than the other.
Benefits of 12V Solar Systems
The biggest benefit of a 12V system is it costs less. A 12V solar panel sells for much less than a 24V. 12 volt PV modules are also more widely available and work well with many small scale solar setups like those in vans and campers.
Solar deep cycle batteries are often 12 volts as well. If your battery requirements are small, a single 12V battery will be fine. And it is easier to find 12V batteries than 24V. If widespread availability is a concern for you, then 12V batteries have the edge. However, 24V systems can do more with less as explained below.
Benefits of 24V Solar Systems
The benefits of 24V solar systems become apparent when you move to medium to large PV modules, inverters and batteries. The bigger your system needs, the more cost effective 24V solar power becomes.
Some of the benefits of a 24V solar system over 12V:
- Use components that need higher voltage
- Capable of charging higher capacity batteries
- Reduce wiring cost
- Compatible with many modern appliances
There are other advantages to using a 24V system. The following explains why it is also more cost effective in the long term.
Use a less expensive charge controller. A 30A MPPT charge controller is needed for a solar array consisting of 4 x 100 12V solar panels. But if you have 24V modules, you can run the same array with a 15A controller. You pay half the price without compromising performance.
Use smaller wires. The higher the voltage, the smaller the solar cable wire needed. Shorter, smaller wires also reduce energy losses, while longer cables increase energy systems loss.
A 12V 200W solar panel on a 16 ft./ 5 m cable generates around 3% energy loss. Doubling the cable length to 32 ft./ 10 m results in a loss of 7% to 10%. By increasing the cable size losses are reduced to 3%, but large cables cost more.
In contrast, a 24V system needs only half the cable wire size of a 12V to run. The same 32 ft. /10 m cable only loses 3% energy, even without increasing cable thickness or size. The longer the cable required, the more efficient 24V systems become.
Use higher capacity batteries. A 12V 100ah battery contains 1200 watts, but a 24V 100ah battery has double that with 2400 watts. You cannot charge a 24V battery with a 12V solar panel because the charging power source has to be higher. With a 24V solar module, you can use a 24V battery.
Although 24V batteries have twice the watt capacity of its 12V counterpart, the weight is basically the same. If you are off the grid and need a large solar array to power your house, battery sizes are crucial.
The safest battery weight a person can lift is about 88 lbs. / 40 kg. That is how much a 120ah to 145h battery weighs. If you need several of these for your system, every pound counts. With a 24V system, you get twice the power without dealing with extra weight.
Larger inverters. Many DIIY setups and RVs use 12V inverters, but if you need a lot of power (between 1000W to 5000W) you should use a 24V inverter. These are more effective in curbing energy losses and transferring power from the battery to your appliances.
12V systems are usually for:
- Small homes
- Camper trailers
- 1000 watts or less power requirement
24V systems are often for:
- Large scale systems
- You need 1000 watts to 5000 watts
In some cases you may want to go for 48V instead of 24V. It really depends on your situation and what type of solar panel setup you have. Contact a professional solar installer if you are not sure which is right for your home.
Now that you know how easy it is to convert 12V solar panels into 24V, you can fine tune your setup to match the voltage requirements. What is important is knowing what your system needs so you can configure the modules properly.