In this article, we are going to cover when is it appropriate to pick a 24V VS a 12V for your particular solar power system setup.
At the end of this simple to read guide, you will understand why people do, the math behind it and the pros and cons.
Let’s get a 10000 foot overview of the pros and cons first.
[Pros & Cons] 12V VS 24V
Note: When we mention a 12V or 24V system, we are talking about the battery bank.
24V Battery
Pros
- Cheaper to build (Wire size is less demanding than 12V)
- Less amp required on charge controller
- High wattage solar panels can be used
- Build for medium size solar power systems
- Great for series connection
- Reduce load on charge controller when using 24V and high voltage solar panels
- Increased efficiency & less lost in the wire
Cons
- Maybe hard to find in your local retailers
- Hard to find 24V inverters
- Requires higher solar panel open circuit voltage
- Can’t run 12V appliances directly without an converter
- Can’t charge vehicle’s alternator
12V Battery
Pros
- Very common to find locally
- Cheaper for a charge controller
- For small solar power system
- Clean setup without too many parts
- Generally safe without shock
Cons
- Much more (copper wire) expensive on wire demand to supply the amperage, aka thicker wires
How Much You’re Saving When Using 24V Over 12V
The 24V setup is much cheaper than 12V, and the pros dramatically exceed the cons. When it comes to cost savings, there are three major factors:
- Bigger wires & lugs cost more to carry more amperage
- Charge controller
- Inverter
- Converter
In average, a 24V system saves you overall
Example:
Assuming we are building a system to supply a 1000W appliance
1000 W appliance on a 12V system.
1000 W / 12 V = 83 amp
1000 W / 24V = 41.7 amp
Wiring distance ( 10 ft)
Wiring
Based on the numbers above for amperage load. AWG stands for American Wire Gauge. It’s a system for sizing wires
On a 12V system (83 amp), a 100 amp wire is recommended 4 Gauge AWG
On a 24V system (41.7 amp), a 50 amp wire is recommended 6 Gauge AWG
Charge Controller
When the battery bank is nearly full, the controller will taper off the charging current to maintain the required voltage to fully charge the battery and keep it topped off. By being able to regulate the voltage, the solar controller protects the battery
24V – Get away with half size of the solar charge controller compared to a 12V
12V – Need a higher amperage load controller and shoots up the price.
You are saving 84% when using a 24V system.
Inverter
Inverters are electrical devices that take the power from your batteries and “inverts” the power from 12v to 110v to work with wall outlets.
Inverter pretty much stays the same for a 12V or a 24V.
You are saving about %50 when using a 24V by using a sm
Converter
A converter turns AC to DC power, both 12V and 24V are in the similar price range all under $150.
