This article will teach you how to convert 36v solar panels to 18v solar panels to charge a 12-volt battery.
When converting your batteries, make sure that the battery’s voltage is higher than what you are trying to charge; we recommend charging 12 volts with a 24-volt panel and 18 volts with a 36-volt panel.
If your battery is too small and can’t be charged, you may need to buy a new one or increase the size of this solar panel.
Below are some informative key points I’ll cover:
- How to convert 36v solar panel to 18v
- How long does it take to charge a 12v battery with an 18v solar panel
- Can a 36v panel charge a 12v battery
I have all the information you need, so be sure to read through the article.
How to convert 36v solar panel to 18v:
To begin, you will need a 36-volt panel and two pieces of wire. These can be salvaged from an old computer power supply or another smaller solar panel than the 36-volt one.
In this case, we could get our wires from the 24-volt panel initially powering this charge controller.
Once you have acquired your wire, cut each wire into two pieces at the point where they attach to the solar panel. On one end of each wire, there should be two wires with a smaller diameter than the other end.
Strip off some of the insulation on this end and solder them together, creating one full-length piece of wire.
Do not desolder the ends where they are soldered onto the solar panel!
You will need these to plug back in later. If you cannot use wires because your original 36-volt wire is soldered directly onto your panels, buy another male/female 10 cm connector set from amazon or eBay.
Both new pieces of 18 volts wired should now have four wires inside instead of two. One end should have two wires with a smaller diameter, and one end should have four.
At the other end of each wire (the part originally attached to the panel), solder or clamp on a connector to plug it back into your solar panel.
Make sure you double-check which wire is positive and negative before connecting them to make sure you do not damage your new 18-volt panel!
This may seem like a lot of work, but it saves you money from buying another 36v solar panel in the long run.
Also, note that even though you are converting this 36-volt solar panel down to 18 volts, all of its original power still gets used for charging because the battery acts as a buffer between both panels.
Convert your solar panels via a charge controller. This MakeSkyBlue MPPT will do that automatically;
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What are some other ways to convert 36v solar panels to 18v?
If you do not have access to a wire or cannot find any after trying this method, you could use diodes instead.
You will need at least one diode for every three solar panels you want to power on independently (not in series with each other), so if you tried to plug in four 18-volt batteries, they would all require six diodes total.
Two of these would be positive, and two would be negative – just like with the wires! Keep in mind that the voltage drop over a diode is about 1.4 volts, so if you convert from 36 volts to 18 volts, there will be a loss of about 5.2 volts per panel.
What are the advantages and disadvantages of converting 36v solar panels to 18v?
The main advantages are financial efficiency by not having redundant solar panels just because they have different voltages and conserving materials such as wire or diodes that might get thrown out otherwise.
The main disadvantage is that it requires more work upfront before the system can run efficiently, but this shouldn’t take more than fifteen minutes for most do-it-yourselfers who already have some background with wiring and solar panels!
How long does it take to charge a 12v battery with an 18v solar panel?
About seven hours. Sizing your battery relative to your solar panels is essential for efficient use in any situation.
What you need to do depends on the charge controller, batteries, and how much total energy you can collect per day based on your latitude.
How long does it take to charge a 12v battery with a 24v solar panel?
About four hours. As always, sizing your battery relative to your solar panels is vital for efficient use in any situation.
The relationship between voltage and charge time is not linear so keep this in mind when choosing two different voltages!
Whatever maximum amount of power that solution can provide divided by however many hours it takes should estimate the number of panels needed.
Can a 36v panel charge a 12v battery?
Yes, it can, but not as quickly since you are at a lower voltage. You will need to do some conversions to maximize the efficiency of your battery charging based on what you have available.
You could use two 18-volt panels or one 36-volt panel in series with an 18-volt if you only want to charge one 12v battery at once. To charge two 12v batteries in parallel, you would need a 24-volt panel.
Solar Panel Voltage and Inverter FAQs
What is the difference between 36v and 18v solar panels?
The main difference is simply voltage. Aside from that, there are no differences in how they work or what components can be used with them.
One volt isn’t much, so it doesn’t make too much of a difference in our daily lives except in electrical systems like cars or grid power!
Different voltages combine to create different charge rates that match different battery types – keep this in mind when choosing what kind of system you want to run.
Does the solar panel voltage have to match battery voltage?
No, the voltage of the solar panel and battery are independent of each other.
You can connect a 36-volt solar panel to an 18-volt battery or even use two different panels in series and the other in parallel (for example, a 24-volt and an 18-volt).
It all comes down to how much power you want to pull from each at once, what you have available for modules, and how many batteries you want to charge at once.
What is lost in charging 12v vs. 24v?
There is not much “lost” when it comes to this conversion – it just takes longer because there is less voltage!
Every battery needs some energy, so if they are connected independently, you’ll lose about 1.4 volts per panel you are losing in the conversion to charge your battery(s). The current does not decrease, just the voltage.
How do I choose Solar panel voltage?
There is no set answer to this question, but you can calculate how much energy your particular panels produce at their max voltage by multiplying the number of amps they put out by the number of hours for one full charge.
This will give you an idea of what kind of system you might want to build!
Everything comes down to cost and convenience: do you want to optimize efficiency or save money? With some math and proper equipment, anything can be possible.
What size inverter do I need for this setup?
It is recommended that your inverter size match up with your battery bank size!
The general rule of thumb is to ensure 20% extra power storage capacity in case of cloudy weather or other appliances which might use more power than usual.
As always, though, there are other variables involved, like how many hours go into charging the batteries and what appliances use them (and how much).
Is it worth the investment to buy a higher voltage panel?
It comes down to how much energy you can save over time. If you are using this system on an RV, boat, or out on the road, for example, where you have limited space and want everything close together, then having higher voltage panels might make sense!
You will be able to charge your batteries more efficiently with less room used on your rooftop or space in your car. For home use, though, it probably doesn’t matter too much as long as you are happy with the result.
What are the disadvantages of converting to higher voltage solar systems?
You have to watch out for just two main things when doing this kind of conversion: safety and efficiency. First, make sure that your equipment is all rated appropriately – if you use a 24-volt panel with an 18-volt battery, the extra exposure could be dangerous!
It might work, but at least double-check before making any connections.
Efficiency is another thing altogether because every battery needs some energy, so if the panels are working harder, they may not last as long over time, even though it can save room on your roof or in your car.
Can we get a higher voltage by combining two 12v panels?
Yes – but keep in mind that each battery needs some energy, so if they are connected independently, you’ll lose about 1.4 volts per panel you are losing in the conversion.
That being said, it will depend on how long your batteries last and how much money you have available- do the math! Also, consider that inverter efficiency decreases at higher voltages, reducing charge time and making your system less efficient overall.