Selecting the right inverter for your off-grid system
When designing an off-grid system, it’s important to take the time to research your inverter options to select the best technology for you and your needs. Inverters fulfill the essential need of turning DC output into AC in order to power your appliances in your home, whether that’s an RV on the open road or a small cabin in the middle of the woods. What’s the best inverter when you’re off-grid? What are solar inverter chargers and should you buy them?
What do inverters do and why do I need them?
As mentioned, inverters serve as the gateway between the photovoltaic system and the devices and appliances drawing energy from your solar panel system. Inverters turn the DC output collected from your solar panels into alternating current (AC), which is the standard used by all commercial appliances.
What is off-grid solar?
Off-grid solar systems, or stand-alone power systems, produce enough energy through the usage of solar panels and battery storage without having to tap into the electric grid. If you live in a mobile lifestyle on the road or in a remote area without reliable and affordable access to the grid, off-grid solar can be a great way to meet your energy needs. In the past, off-grid systems were often out of reach for most people because of the high costs of inverters and batteries. However, battery and inverter prices continue to drop and technologies continue to improve, making off-grid solar financially feasible for more people.
Off-grid systems utilize batteries to store energy produced from solar panels. Systems must be sized and designed to fit a variety of needs throughout the year, especially in the winter when there are fewer sunlight hours. Off-grid systems need a standalone inverter.
Which is the best solar inverter for me?
Everyone’s installation is different, but if you have an off-grid system, you’ll most likely be choosing between a pure sine wave inverter and a modified sine wave inverter.
Pure Sine Wave Inverters: Pure sine wave inverters are capable of producing smooth quiet, and reliable electricity to operate appliances and electronics without any interference. Like its name suggests, pure sine wave inverters produce current in a pure sine wave shape. Renogy sells a range of pure sine wave inverters of varying capacities to fit your solar installation and your energy needs. Renogy inverters also provide overload protection for both DC input and AC output to prevent damage to the components and the unit.
Modified Sine Wave Inverters: In modified sine wave inverters, the polarity abruptly switches from positive to negative versus a true sine wave. When looking at the wave, it has a stair-step, square pattern, where the polarity is flipped back and forth. That choppy wave can negatively affect more delicate, sensitive equipment. If you have medical equipment you need to power, such as a CPAP machine, you won’t be able to use a modified sine wave inverter. Additionally, in many cases, you’ll hear a hum with devices attached to a modified sine wave inverter. However, with simple devices and appliances, modified sine wave inverters typically do the job.
What can I run with a modified sine wave inverter?
Modified sine wave inverters can be used in simple systems without sensitive electronics. If there isn’t an AC motor and isn’t a delicate piece of medical equipment, you may be fine. Old tube tvs, water pumps, and phone chargers usually operate ok with a modified sine wave inverter.
Appliances like refrigerators, microwaves, and compressors that use AC motors won’t run as efficiently on a modified sine wave inverter. Some fluorescent lights will also not operate quite as bright, and some may buzz or make humming noises.
What do I need a pure sine wave inverter to run?
• Appliances with AC motors: Microwaves and refrigerators
• Medical equipment, such as CPAP machines with humidifiers
• Sensitive electronics
• Laser printers
• Newer TV’s
• Appliances with electronic timers or digital clocks
Your laptop may be ok with a modified sine wave inverter, although some claim that not using a pure sine wave inverter will shorten the lifespan of your laptop’s battery.
What are pros and cons of using a modified sine wave inverter?
Pros:
• Less Money upfront: Modified sine wave inverters are typically cheaper than pure sine wave inverters, so if you’re on a budget and you’re only powering simple appliances, modified sine wave inverters may be enough to meet your energy needs.
Cons:
• Lower efficiency: Modified sine wave inverters are not nearly as efficient as pure sine wave inverters.
• Will not work with many appliances: As mentioned above, there are a variety of appliances you need a pure sine wave inverter to run, as TV’s, microwaves, and inverters.
What is the best off-grid inverter?
If your budget allows, pure sine wave inverters are typically the best choice because they can be used to power nearly all appliances, are efficient, quiet, and safe. Renogy’s pure sine wave inverters are equipped to meet the needs of your off-grid system.
Do I need a solar inverter charger?
Solar inverter chargers are a powerful, multitasking device for your solar installation. Renogy offers a few solar inverter charger options for purchase. As the name suggests, solar inverter chargers fulfill both inverter and charging roles.. Inverter chargers are great for RV’s, boats, and other off-grid applications because the inverter charger can charge the battery bank from shore power, and the inverter will then convert the DC power to run AC loads in the space. They come in handy when you’re in areas where you may not be getting enough sunlight alone to charge your battery bank. The Renogy 3000W pure sine wave inverter charger can be used for a variety of applications. The device can charge and maintain a battery bank when connected to shore power, as well as convert DC to AC for your appliances.
How many batteries do I need for a 2,000 watt inverter?
Inverters are sized in watts, just like solar panels. So if you have a 2,000 watt solar panel system,you’ll need at least a 2,000 watt inverter.
To figure out how many batteries you need for your 2,000 watt system, you can use the following equation: expected run timed needed * wattage of your inverter = total/voltage.
So if you have a 2,000 watt inverter and you need to have 3 hours of run time, you get 3 hours of runtime * 2,000 watts=6,000 watts total/12 volts DC = 500 amps total. You’ll need a total of 500 amps of stored power in the batteries. Remember you won’t want to fully deplete your batteries, so keep that in mind when calculating your needs. In this example, you’d need 160 amps per hour. So, you’ll need at least four 50aH or two 100aH batteries for a 2,000 watt system.
How much are solar inverters?
For standalone inverters in off-grid systems, modified sine wave inverters typically cost between $50 and $600. Pure sine wave inverters cost between $150 and $900.
Conclusion
Solar inverters are a key component of any solar installation. They fulfill the essential function of converting DC output from your solar panels into alternating current to power your appliances. If you’re building an off-grid solar installation, pure sine wave inverters are typically the best choice because they are quiet, efficient, and compatible with a wide range of appliances. If you’re in an area without steady sunlight and also have access to shore power or a generator, you might also consider purchasing a solar inverter charger to keep your battery bank charged. With the decreasing costs and ever-improving technology of inverters, there’s never been a better time to go off-grid with solar.
