We frequently get the question about our solar panels –
“Are they 12v or 24v?“
This post answers that question and dispels old myths that haunt the solar industry.
The fact is that most people who are wondering if a panel is 12 volts or 24 volts have been told that solar panels must match the battery voltage. This is ONLY true if you are using a PWM charge controller.
With an MPPT charge controller, the voltage does not matter as the charge controller switches the power down to the right voltage for your batteries.
MPPT stands for Maximum Power Point Tracking. MPPT is a technology that allows the charge controller to observe and regulate the energy going from solar panel to the batteries. Solar panels show changeable outputs according to weather conditions. MPPT charge control devices can match the solar panel voltage with battery voltage to maximize the charge efficiency. In these systems, the full power of solar panels can be used by balancing between voltage and current according to the P = V x A equation. For example, the amount of current drawn from the panels reduced to protect the voltage when the weather is cloudy. When the weather is sunny, it is allowed to draw more current.
The primary difference between PWM and MPPT charge controllers is that the MPPT devices are more efficient. MPPT charge controllers are 30 % more efficient in charge efficiency compared to their PWM cousins. Panel voltage and battery voltage should be matched in PWM systems. In MPPT systems, the panel series are allowed to have higher voltage than batteries. This means more flexibility for system growth.
MPPT charge controllers are a little more expensive compared to PWM, but their efficiency greatly outweighs this small extra cost. With this extra efficiency, you get extra features that make life with solar easier, such as wifi, large LCD screens (sometimes color), better heat dissipation, and battery temp monitoring. Also, MPPT charge controllers are usually a lot safer due to having better build quality.
Another issue facing PWM charge controllers is that they are usually cheap in both price and build quality. We have seen many examples of cheap PWM charge controllers that have had a catastrophic internal short causing the unit to literally melt down. A charge controller the size of the thermostat in your Kitchen is not going to be reliable. Here are some examples:
In summary, there’s no need to worry about the voltage of your solar panels if you choose a modern and efficient MPPT charge controller for your solar system.
Many beginners start their research into solar power with the goal to power their homes with solar panels. While this is a fantastic end goal for most consumers, it sometimes leads solar users to overlook useful small-scale implementations of solar power.
The following projects can give a new solar power user important experiences before they make the leap to powering their entire home with solar energy. We’ll be sharing a few of these common clever uses for solar power that you can implement with relatively minimal experience and oversight.
All of the pictures in this article were sent to us by customers, so these are real projects that you can really do!
Solar Panel Kits
We’ll be powering each of the projects below with a solar panel kit like the one linked below:
Before we begin, we’ll be giving a brief description of the important pieces of this kit.
The Solar Panel is the central piece of this kit. The panel is what we set out in the sun to gather solar energy needed to power your solar appliances. It’s understandable for newbies to want to simply connect your panel to your appliance or a 12V battery. After all, solar panels give energy, right? However, most applications need a specific voltage or they’ll be damaged or non-functional.
If we want to store solar energy in batteries, we have to be extra careful. Lead-acid batteries are designed to only accept a certain size of charge, shouldn’t be overcharged, and shouldn’t be discharged to less than half-capacity. How do we ensure that all that happens? We do that with the second important part of the kit:
The Solar Charge Controller is placed between our solar panel and battery or appliance. The solar charge controller ensures that only the appropriate voltage is allowed to pass through from the solar panels. The solar charge controller can also ensure that batteries are not discharged below safe levels.
Depending on your application, you may need to purchase an additional Battery, not included in this kit. There are several types of batteries, from lead-deep cycle to 6-volt golf cart batteries, to expensive lithium batteries. To read more about batteries or the parts of your solar kit, you can read our articles here:
A relatively simple solar setup in a shed or garage can ensure that your power tools always have fully charged batteries, regardless of the electrical grid’s status. To charge your power tools, we’ll need to add one extra piece of equipment, an Inverter. Inverters take the direct-current(DC) energy from your battery and convert it into the alternating-current(AC) that most outlets use.
With this setup, you can install your solar panel to the roof of your shed, then pass wires inside the structure to your solar charge controller. From there, you can pass the wires through to your battery and inverter. Not all inverters are created equal, so be sure to buy one that can handle the power load that your battery charging station will draw.
Freeing Your RV From Campsites/RV Boondocking
One of the most common and useful applications for solar power is installation into RVs. Most RVs typically contain two kinds of batteries. 12-volt car batteries, used for the engine and headlights, and 12-volt lead deep-cycle batteries for everything else. Car batteries are designed to deliver huge amounts of power all at once (like for turning over the engine.) Lead deep cycle batteries are used to power all of the appliances inside an RV.
The capacity of an RV’s deep-cycle battery is typically the limiting factor for “boondocking” away from campsites in an RV. While an RV’s water tanks can provide water for up to two weeks, it’s not uncommon for an onboard deep-cycle battery to only power appliances for two to three days. Solar panels can greatly extend the amount of time your RV can stay away from hookups.
RVs have a few advantages over other solar setups in that they already contain several important pieces of equipment. Because your RV’s battery runs on 12 volts of direct current, most RV’s will include an onboard inverter to provide 120V of alternating current to your microwave, TV, or outlets.
This inverter typically is connected to a set of circuit breakers to increase safety. It’s possible to tap into these electrical lines with your solar setup to provide free recharging with solar power.
The first step to incorporating solar power into your RV is to install the panels. Most people choose to install the panels on top of the roof, occasionally incorporating frames that can tilt to better catch sunlight.
After the panels are installed into the roof of the RV, the wires should go to the solar charge controller. This should be placed somewhere easily accessible so you can check the battery level and the current flowing from your panels to the RV.
After you’ve connected your panels to the solar charge controller, you should wire them to your battery bank. There are various ways to accomplish this that vary depending on the location and setup of your specific model of RV. Check the schematics for the best places to make contact with either your battery bank or wires connected to your battery bank.
Be sure to incorporate extra breaks for safety. You’d rather go through the headache of switching a fuse than the headache of an electrical short and potential fire!
Solar Pool Pumps
Another common use for solar power is to use it to power pool pumps. A pool pump that doesn’t draw any extra power from the grid will save you money in the long term. If you have a modern pool pump, especially one that was designed to work with solar power, switching to solar power will save you on your monthly electric bill.
Many solar pumps run on direct current (DC), so no inverter is needed to connect them to your solar panels. You should be sure to use a solar charge controller to limit the incoming voltage, however. Solar panels can give off variable energy when it’s cloudy or raining, so it’s important to check that your pump won’t break or wear out when supplied with variable energy.
Obviously, your pool pumps won’t work at night. However, most pools will stay clean with pumps that work over the course of a sunny day. You’ll also find that your pool pumps will work for more hours during the longer summer days, which is convenient as your pool will see greater use during the hot summer.
Solar Powered Golf Carts
If you’ve ever been on a college campus or a large ranch, you know how convenient a golf cart can be for quickly getting around. Golf carts are used for the transportation of people and materials in a wide variety of locations and settings around the country. They’re used by security patrols, farmers, and camp counselors.
Adding a solar panel or two to the roof of your golf cart can greatly extend the battery life between charges. While a fully-charged golf cart typically has a range of 30-45 miles before needing a recharge, a golf cart with a solar panel setup has theoretically infinite range (provided you let it sit in the sun between uses!)
Golf carts are great candidates for solar systems because they run on a direct current (DC) system. As before, we’ll need our panel, a solar charge controller, and connections to the golf cart’s battery bank.
Our solar charge controller will regulate our charging voltage depending on your golf cart’s rating. Some carts operate at 36 volts, and some at 48 volts. You’ll want to make sure your charge controller is rated for the appropriate voltage.
After installing your solar panel(s) onto the roof of the golf cart, run the wires down to the battery bank. Connect them to your charge controller, then onto the battery bank’s positive and negative leads.
Solar Powered Air Conditioning
While solar-powered air conditioning technology has massively advanced in recent years, it’s still a relatively new technology. The main issue is that air conditioning units require a lot of energy to function. That means that, unless you’ve invested in a significant battery bank, you’ll likely only be able to power your air conditioning units during the day. In some climates where nights are cool, this may not be a terrible idea.
Luckily for the rest of us, there are hybrid air conditioning units. During the day when energy is most expensive, hybrid air conditioning units draw their power from solar panels. When night falls alongside energy costs, these hybrid units draw their power from the electrical grid to continue cooling your rooms.
These hybrid units are still a relatively new and expensive technology. If you’re planning on investing in these units, it may be in your best interest to look into powering your entire home with solar power. You can read more about powering your home on-grid by reading our article here:
For many beginners, planning out a small project like the ones listed above is a great way to dip your toes into solar energy. Installing a few panels onto your shed will allow you to power your power tools alongside some LED lights, and will teach you how the different pieces of equipment interact. Connecting a solar panel to your pool pump or golf cart will lower your energy costs and, in the case of the golf cart, extend the time between recharges.
Once you’ve learned a few things about solar power, a larger project would be to install panels onto the roof of your RV. This will allow you to dry camp and leave the civilized world behind without worrying about your microwave or TV running out of juice.
Before starting any of these projects, we highly recommend searching for a video tutorial or reading one of our guides. If you don’t know what you’re doing, it’s better to spend a few hours learning rather than getting shocked. We like to say measure twice, cut once.
Here Are The Top 5 Companies Making the Switch to Solar
Thinking about the benefits of solar energy? So are a lot of the world’s largest companies. Whether the goal is to reduce carbon emissions, qualify for tax benefits, or reduce electricity bills, both companies and you benefit from renewable energy.
Anheuser-Busch
The world’s largest brewing company, Anheuser-Busch, is making the change to sustainable energy. The company already uses wind power to make its beers, and just announced plans to work with a solar developer to build a 2,000 acre solar farm en Pecos County, Texas.
Anheuser-Busch originally planned to have all American-made beers brewed exclusively with renewable energy by 2025, but with the solar farm’s completion in 2021, they’ll be four years ahead of schedule.
“Sustainability is our business, because we rely on crops and water in order to have our final product,” said Michel Doukeris, CEO. Other brewing companies are also working to be eco friendly – MillerCoors installed their own solar panels in 2015, which will reduce carbon emissions and water consumption by almost 700 million gallons in the next 30 years.
Walt Disney World
The most magical place in the world is also becoming greener! Walt Disney World announced a second solar plant in April, and with 270 acres, it’s twice the size of Magic Kingdom Park. The 500,000 panel and 50 megawatt farm will generate enough energy to provide up to 25% of Walt Disney World’s electricity. That’s the equivalent of “removing 10,000 cars off the road”, according to Angie Renner, Environmental Integration Director of Disney Parks
The plant will follow a smaller 22-acre solar installation built in 2016 near EPCOT shaped like Mickey Mouse. “It’s been a lot easier [for companies] to be cost effective as well as to meet the goals of renewable energy,” said John Giddens, director of Reedy Creek, the Walt Disney World Resort district.
“I hope everyone is as excited as we are to harness the power of the sun and about this new renewable facility that’s helping bring magic and clean energy to the Disney Resort”, added Renner.
Google
Google has also added more solar plants to support their data centers. Construction in Alabama and Tennessee began in January to build two enormous plants that will generate up to 413 megawatts, enough to supply almost 80,000 houses!
The solar parks will have 1.6 million panels total and are the largest plants ever built for Google.
“We’re committed to leaving the world better than we found it. After years of hard work we’re proud to have reached this significant milestone,” said Tim Cook, CEO of Apple. “We’re going to keep pushing the boundaries of what is possible with the materials in our products, the way we recycle them, our facilities and our work with suppliers to establish new creative and forward-looking sources of renewable energy because we know the future depends on it.”
Apple’s new headquarters in Cupertino, California, became the largest office to be certified LEED (Leadership in Energy and Environmental Design) in the U.S. last year. The rooftop solar installation provides 17 megawatts that go to the public grid during low-use times. Now that’s a good neighbor!
Walmart
Walmart’s been working to put their slogan of “Save Money. Live Better.” in practice for twelve years through solar energy – they’re constantly adding solar panels and plants to supply their stores throughout the states and Puerto Rico. In the last year, Walmart announced new solar energy projects in California, South Carolina, Illinois, Alabama, and other states, inching them closer to their 2025 goal of half their energy being supplied through renewable energy source.
“Our work in renewable energy is an ongoing process, one that we are fully committed to because the future of the environment depends on it—and our customers deserve it”, wrote David Ozment, Walmart’s Energy Director.
Commercial and Residential Benefits
Whatever your interest in solar panels, with Rocket City Solar you can get the same benefits with our solar panels that companies get with large solar installations. Visit our page to get more information, contact us, or buy panels that will save the environment and your wallet.
