AC vs. DC Solar Panels: Which One Is Better?

ac vs dc power

In this easy-to-read guide, we’ll take you through a complete breakdown of AC and DC solar panels while talking about the big factors that go into picking the right type of solar panel such as voltage ratings, storage systems, and costs.

THE BIGGEST DIFFERENCE

When sunlight hits a solar panel, the sun’s rays excite electrons within the cells of the panels, causing the electrons to start flowing in one direction—this results in a singular, one-direction flow, also known as direct current, or DC power. In contrast, alternating current, or AC power, is basically what it sounds like—it’s electrons that are flowing in alternating directions.

Most solar panels use DC power, similar to most batteries that you’ll find. Since power travels between the positive and negative terminals in a battery, it never flows in a different direction which makes it a direct current.

Where will you find AC power? You’ll find AC power being used within the city’s electric grids and within your home—most of your house’s appliances use AC power since the power being supplied goes into your appliances and back out once there’s enough power going through.

TYPICAL VOLTAGE RATINGS

battery voltage

When it comes to deciding what the typical voltage ratings are on an AC solar panel vs. a DC solar panel, we have to look at the conversion factor that comes from the technological differences between AC and DC solar panels.

Since most solar panels produce DC power, you may have guessed that some sort of inversion needs to be done in order to invert DC to usable AC power in homes and appliances.

That’s where the inverters come in! Inverters transform DC power into AC power, either from the solar panel to the appliances in your home or from the stored DC power in solar batteries to your home. There is a disadvantage in this system, however.

Since the raw power has to be inverted from DC power to AC power, there is a slight drop in voltage which, depending on the efficiency of the inverter, may cause you and your home to lose valuable power over time.

AC solar panels are usually referred to as free-flowing solar panels—this is because AC solar panels do not need an inverter for the power to be usable; it’s been usable ever since it left the solar panel. Since they don’t need an inverter to invert DC power into AC power, the voltage rating usually stays true to the actual voltage rating within an AC solar panel.

AC AND DC-COUPLED ENERGY STORAGE SYSTEMS

solar panel AC and DC diagram

Most DC-coupled energy storage systems are used for RVs and homes that are completely off-grid since they don’t need to interfere with the city’s electrical grid, but over the last several years, component technologies within solar systems have led to the development of AC-coupled energy storage systems.

Since the technology is still fairly new, DC-coupled systems are still the most efficient method available for energy storage, but it’s only the most efficient if the DC-coupled system is paired with a solar charge controller or a hybrid solar inverter. If you’re not familiar with charge controllers or inverters, and you’re wanting to know more about them, check out our article on solar system components: “Core Solar Panel Components.”

Over the next few years, as solar power becomes more prominent, we’ll be able to see a more-efficient AC-coupled energy storage system due to the advancements that we’re seeing around us everyday.

COST COMPARISON

reduced cost

The cost for solar panels mostly depends on efficiency and voltage ratings—a 100 Watt solar panel is going to be cheaper than a 350 Watt solar panel, but the 100 Watt solar panel is going to bring you less power in the long run, even if it’s more efficient.

But when we’re comparing AC solar panels to DC solar panels, there’s one component that basically decides the price for both types of solar panels.

Since AC solar panels bring power to your home in alternating current, there’s no need to purchase an inverter for your solar kit—this is because the solar inverter comes built-in with the solar panel which is why AC solar panels cost more than DC solar panels. To put it in shorter words, when you buy an AC solar panel, you’re paying for a solar panel and a solar inverter.

DC solar panels do not come with an inverter—it’s something that you have to purchase separately, and depending on what kind of solar panel and inverter you buy, sometimes it ends up saving you a little more money instead of buying an AC solar panel with the built-in solar inverter.

Since the solar inverter comes built-in, the power conversion still takes place, and the voltage rating does drop, but it doesn’t drop as much if you were to buy a DC solar panel with a separate solar inverter. Over the long run, you won’t even be able to notice the slight drop in voltage for the AC solar panels.

If you need to get a solar inverter, please check out this guide

COMMON FAQS

There’s a lot of questions that people have asked about the DC solar panels and AC solar panels. We’ve hand-picked a few of them to talk about them briefly.

Can I use AC power on my solar panel?

Yes, you can use AC power on your solar panel as long as it’s designed for AC power. The whole deal with AC power is that it can alternate directions and can go out the same way it came in. Be careful, though! You can use AC power and DC power on an AC solar panel, but you can ONLY use DC power on a DC solar panel since it’s designed for one-way travel, only.

Why is DC power produced from solar panels?

When sunlight hits the upper silicon layer, the electrons within the layer get excited and travel in one direction through the separation layer towards the bottom silicon layer. Since this direction is singular, solar panels produce direct current which is unable to go back the opposite direction.

If the solar panel is DC rated, that’s all—from here on, the power can go to a battery or to an inverted, but if the solar panel is rated to be AC, then right after the bottom silicon layer is a built-in solar inverted that will convert the power into AC power immediately to be used in appliances.

As the years go by, more technology is constantly changing how solar panels are built. Instead of using silicon layers, material engineers are trying to use other materials to try to get more electrons excited with less sunlight. So far, they’ve been able to push cells closer together in order to make solar panels more efficient, but technology is always evolving!

What is the main difference between AC and DC-coupling?

The main difference between AC and DC is usually found within amplifiers or oscilloscopes. When using AC-coupling, you’ll only be able to see AC power coming through your system, as AC-coupling will only allow the flow of AC power. 

If you’re wanting both AC power and DC power to flow through your system, use DC-coupling as it is more beneficial and eliminates the use of an inverter component.

What is the best voltage for solar panels?

The average voltage for solar panels is usually 12 volts—this type of solar system will usually supply under 1,000 Watts and has the capability of powering RVs, motorhomes, vans, camper trailers, small cabins, or even smaller houses. If you’re wanting between 1,000 Watts and 5,000 Watts for something bigger, use a 24 volt solar system, as it can usually power a medium-sized house easily.

On rare occasions, if you’re wanting more than 5,000 Watts, go for the 48 volt solar system which is capable of powering large houses with more than four bedrooms. If you fall in the middle of a category of Wattage, always go for the one higher than what you need—if you’re stuck between getting a 24 volt system or a 48 volt system, go for the 48 volt system.

Even though it’ll be more expensive, you’ll always want more rather than less. Plus, it’ll save you money and electricity in the long run.

Is 24 volts faster than 12 volts?

24 volts isn’t necessarily faster, but it is a lot more advantageous than 12 volts. In many cases, 24 volt batteries or set-ups will eliminate half of your wires if you originally had a 12 volt system. Not only will motors and spindles run at twice the rotational speed, it’ll provide more torque with a larger voltage.

How many solar panels will it take to charge a 12 volt battery?

If the battery is 200 Ampere-hours (it usually is), we can multiply 12 volts by 200 Ampere-hours and end up with 2,400 Watt-hours. If you have two 120-Watt solar panels, you’ll have a combined total of 240 Watts. Dividing 2,400 Watt-hours by 240 Watts will give you 10 hours. So basically, it’ll take two average solar panels and ten hours to fully charge a 12-volt battery.

Can solar panels produce 240 volts?

Yes, solar panels can easily produce 240 volts! DC solar panels, on average, produce anywhere between 200 volts and 500 volts. This voltage will then be inverted to AC power at around 120 volts or 240 volts of AC power to be used within a home or within appliances.

AC solar panels will usually only produce around 240 volts just for consistency within home appliances and other operations. But be careful! To achieve the maximum voltage output, you’ll have to make sure that the solar panel is clear of any dust or debris, and you’ll be able to get the most power out of your solar panel only when the sun is exactly perpendicular to the solar panel.

For many people, the most that your solar panels will give you will be between the hours of 10 AM and 2 PM.

WRAPPING UP

Hopefully, this guide was enough to give you a start on whether you’re wanting a DC power or AC power solar system. In many cases, people are generally happy with DC setups since that’s what a lot of people have, and if you’re ever confused about a setup, you can always ask someone who’s had a similar setup.

With AC setups, you’ll be eliminating a component and wiring complications within your system. Some people do struggle with storing AC power within batteries since most batteries will only allow the input of DC power because of the two different terminals.

Good luck in your next solar setup!

Kabeer Bhatia

Kabeer Bhatia has several years of experience camping and backpacking, and focuses more on the technical side of wilderness technology including solar energy.

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