Power Inverter Buying Guide - Tripp Lite - Eaton

What is an Inverter?

A power inverter is a device that converts low-voltage DC (direct current) power from a battery to standard household AC (alternating current) power. An Inverter allows you to operate electronics, household appliances, tools and other electrical equipment using the power produced by a car, truck or boat battery or renewable energy source, such as solar panels or wind turbines. An inverter gives you power when you are "off the grid" so you have portable power, whenever and wherever you need it.

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What is the difference between an inverter and inverter/charger?

An inverter simply converts DC (battery) power into AC power and then passes it along to connected equipment. An inverter/charger does the same thing, except it is an inverter with batteries attached. It remains connected to an AC power source to continuously charge the attached batteries when AC utility power – also known as shore power – is available.

An inverter/charger is a quiet alternative to gas generators, with no fumes, fuel or noise to deal with. During prolonged outages, you may need to run a generator occasionally to recharge the batteries, but the inverter/charger lets you run the generator less often, conserving fuel.

What is a Power Inverter Used For?

Simply put, a power inverter delivers AC power when there's no outlet available or plugging into one is impractical. This could be in a car, truck, motorhome or boat, at a construction site, in an ambulance or EMS vehicle, at a campground or on a mobile medical cart in a hospital. Inverters or inverter/chargers can provide power for your home during an outage to keep refrigerators, freezers and sump pumps operating. Inverters also play an essential part in renewable energy systems.

DC to AC Conversion: How Inverters Work

The direct current, or DC, power that comes from a battery flows in one direction from the battery's negative terminal, through the completed circuit and back to the positive terminal of the battery. However, typical 12-volt or 24-volt batteries provide only relatively low-voltage power. Depending on your location, appliances need to run on 120-volt or 230-volt AC power.

120V Power Inverters

230V Power Inverters

An inverter tackles this disparity by increasing the voltage and using transistors or semiconductors to reverse the polarity of the DC input back and forth rapidly, sending it one way through the circuit, then very quickly reversing it and sending it the other way. In most cases, it does this 60 times per second (60 Hz).

Frequently Asked Questions

What is the difference between an inverter and an Uninterrupted Power Supply (UPS)?

Inverters and UPS systems both provide power from batteries in the absence of AC power. A UPS typically includes the battery and battery charger in one standalone unit. Batteries for an inverter are generally user-supplied.

A UPS system also can have communication with the equipment that it is powering, letting the equipment know that it is operating on standby, giving it shutdown warnings or communicating with the human in the loop. Inverters typically don't have this capability.

Depending on the inverter, it will respond to a power outage in 4.2 to 16.7 milliseconds. A UPS responds in a fraction of that time, making the UPS a better choice for applications that must remain powered, such as computer networking equipment.

What is the difference between an inverter and a generator?

A generator runs on gasoline, diesel fuel or propane to produce electric power. An inverter converts DC power stored in batteries to AC power needed to run tools, electronics, appliances and other devices.

A generator may be a better choice when large amounts of power are needed for prolonged periods. However, an inverter/charger is a cleaner and greener choice. It is quiet and fume-free, making it preferable for residential areas or for use indoors.

An inverter/charger can work along with generator power when the generator is running, allowing you to turn the generator off for periods of time to save fuel without turning off your equipment.

What is an inverter/charger?

An inverter/charger converts DC (battery) power into AC power and then passes it along to connected equipment. When it is connected to an AC power source, it continuously charges the attached batteries. During a power outage, the inverter/charger will automatically switch to battery power to provide power to connected equipment. The batteries will be recharged when the AC power source becomes available again.

How do I use an inverter for basic home emergency backup power?

Most often, emergency home backup power runs off a standard car battery, essentially turning your car into a generator. The car should be kept running while the inverter is in use to prevent the battery from becoming depleted. The inverter can still be used if the car is off, but this is not recommended for prolonged periods. If you do use the inverter without the engine running, start your car up every hour and let it run for about 10 minutes to recharge the battery.

To create an emergency backup system without a vehicle, you can hook up two 12V car batteries to one inverter. That will provide enough power to run the average household refrigerator for up to two days, depending on the size of the batteries and the size of your fridge. It's a smart idea to have a spare battery or two on hand in case the duration of the power failure exceeds your battery runtime.

Look for an inverter with a wattage capacity greater than the appliances you need to keep running. Refer to Table 2: Typical Wattage of Common Home Appliances below. Ready to buy? See our recommended inverter/chargers for emergency home backup power.

Can I power my home using my car and a power inverter?

Absolutely! First, know the total wattage of the appliances you need to keep running using the guidelines given below. This will help you buy the right inverter for your home emergency backup system.

An inverter is not waterproof, so keep it out of the rain, as well as away from dust and direct sunlight. Although you can connect the inverter to the vehicle's battery using jumper cables and alligator clips, the preferred method is with a ring terminal that fits securely over the inverter post. Then connect an extension cord no more than 200 ft. from the inverter to the appliance(s) you want to run. Beyond this distance, you are likely to experience signal loss.

To keep the battery charged, you should run your car for about 10 minutes every hour. The inverter will still work when the car is off, as long as you have not depleted the battery.

Does an inverter provide surge protection?

Yes. Because an inverter converts DC power to AC power, the AC output is conditioned before it reaches your equipment. The inverter provides stable output voltage and frequency to protect your equipment from power surges and line noise interference, allowing your equipment to perform at its peak.

Can an inverter power a refrigerator or freezer?

Yes, but there is an important point to keep in mind. When a refrigerator or freezer cycles on, it will draw a high start-up surge of power, several times the wattage it requires when running continuously. Make sure your inverter can handle the peak surge. As a rule of thumb, ensure your inverter can handle a peak surge of 500-750W for a refrigerator and 500-W for a chest freezer.

What kind of battery should I use with my inverter?

Most commonly, 12V batteries like the one in your car are used to power inverters. Heavy-duty inverter/chargers are available that use 24V, 36V or 48V batteries for applications requiring higher wattages. Make sure the batteries you choose match the input voltage capacity of your inverter.

Deep cycle batteries look like ordinary car batteries, but can provide sustained power over a longer period of time and run reliably until discharged up to 80%. They are ideal for inverter applications, especially in RVs, boats and off-the-grid renewable energy because of their ability to be almost completely discharged before they need to be recharged.

Along with batteries, you'll need a fuse and fuse holder. One of the easiest types of fuses to use is an "ANL" fuse that can be spliced into the positive wire coming from your battery pack.

What type of cable should I use to connect batteries?

Most inverters are sold without cables so the user can select the cable best for their application. In general, the distance between the battery and the inverter should as short as possible, ideally 10 ft. or less. Cables used for connecting inverters should be type SGX, which is the type of cable typically used to connect a battery to a car's electronic system and ground it.

The below recommended wire gauge table is a general rule of thumb. The actual size wire you need will vary based on the voltage of your battery, the total amps your equipment is drawing and the length of the cable. Our best advice is to stick to what is specified in your inverter's owner's manual.

Table 1: Recommend Wire Gauges

Inverter Continuous Wattage Recommended Wire Gauge < 500W8 AWG 500 - W4 AWG - W2 AWG - W1/0 AWG > W4/0 AWG

Is a pure sine wave inverter really important?

Depending on what equipment you're using the answer could be a resounding yes. A pure sine wave inverter produces a smooth, sinusoidal AC output with very low harmonic distortion. Sensitive electronics, variable-speed tools, medical equipment such as oxygen concentrators, TVs and A/V components, fluorescent lights with electronic ballasts and any appliances with microprocessor control will not run well under modified sine wave power.

What size power inverter do I need?

To know the right size inverter for your application, you need to total up the wattage of all the appliances, tools or electronics that will run off the inverter at the same time. Many appliances and power tools have their wattage rating indicated on a label on the product itself or in the item's owner's manual. If your devices indicate only amps, the wattage can be arrived at using this simple formula:

Volts x Amps = Watts

Example: You want to run a small mini fridge. You know from the product label it uses 0.7 amps. In the U.S., voltage is 120. Therefore:
120 x 0.7A = 84 Watts

Now factor in how long you want the device to run. This is its runtime. Assuming you are using 12V batteries, divide the total watts by 12.

In our mini fridge example:
84 ÷ 12 = 7 DC amps

This is the DC amp hours required to run the fridge for 1 hour, if it were to run continuously. You'll need to observe the fridge running for a period of time to determine how long it actively runs, so observe it for 15 minutes and record the length of time it runs.

Let's say you want the fridge to run for 12 hours before the batteries need to be recharged. Your observation shows the fridge runs for 5 minutes during the 15-minute observation period. Use this formula:

Active runtime required = Minutes Running ÷ Minutes Observed x Total Runtime Required
12 Hours = 5 Minutes ÷ 15 Minutes x 4 Hours

Next, multiply the DC amps required by the number of hours you estimate you can operate your fridge without charging the batteries.

7 DC Amps x 4 Hours = 28 Amp-Hours

Now you should factor in an adjustment for variable conditions that might affect how frequently the fridge runs, such as warmer weather, opening the fridge, etc. A good rough estimate is a factor of 1.2.

28 Amp-Hours x 1.2 = 33.6 Amp-Hours
This is the minimum amp-hours your batteries must supply.

How much wattage do common home appliances and tools use?

This table of common appliances, electronics and tools will help you estimate your needs. Be sure to check the product label for the actual wattage requirements, and remember that many tools and appliances have significantly higher peak surge requirements when they start up/cycle on.

Table 2: Typical Wattage of Common Home Appliances

Device/Appliance Typical Wattage Desktop Computer with Monitor200 - 400W Laptop Computer20 - 75W Inkjet Printer15 - 75W Laser Printer500 - W Satellite Dish75W Gaming Console125W LCD TV, 32"50 - 70W LCD TV, 42"90 - 250W DVD Player40 - 50W Table Lamp with Incandescent Bulb60W Table Lamp with CFL Bulb13 - 15W Table Lamp with LED Bulb6 - 9W Fluorescent Tube Light40W Blender300 - W Toaster800 - W Coffee Maker, Drip550 - W Coffee Maker, Keurig200 - W Microwave Oven - W Mini Fridge350W Refrigerator, 15 cu ft.240W Chest Freezer 15 cu ft.180 - 500W Vacuum Cleaner300 - W Tabletop or Box Fan50 - 120W CPAP Machine200W Hair Dryer - W Flat Iron800 - W Sump Pump850 - W Space Heater - W Furnace Fan75 - 400W Electric Drill700W Electric Screwdriver60 - 300W Circular SawW Jig Saw350W

If you're stepping into the solar world, you'll quickly learn that the inverter is the brain of your system. It's not just a box on the wall — it's what turns the sun's energy into usable power for your home. Choosing the right one is crucial; it's a decision that affects not only how well your solar panels perform but also how efficiently you can use that power in your daily life.

This guide will walk you through the essentials of solar inverters. We'll help you understand what they do, why they're important, and what you should look for when choosing one. In this guide, we'll cut through the jargon to give you a clear picture of what makes a good inverter and how to find one that aligns with your energy needs and values.

Understanding Solar Inverters

Before diving into the factors to consider when purchasing your own solar inverter, it’s important to know that not all inverters are created equally.

When researching you may come across the descriptors “single-phase” and “three-phase” – a handy rule of thumb to distinguish between single-phase and three-phase inverters is this: single-phase power supplies are typically found in residential homes, whereas commercial or industrial settings often require the more robust three-phase supplies.

For the scope of this article, we'll focus on single-phase inverters, as they are the go-to choice for residential solar energy systems, offering an ideal blend of efficiency, affordability, and simplicity for your home.

An inverter's job might seem straightforward: it converts the DC power from your solar panels into AC power for your home. But there's more to it than just conversion. The type of inverter you choose can affect everything from the efficiency of your solar setup to the way you monitor your energy production.

There are three main types of inverters and each comes with its own set of benefits and considerations:

String Inverters:

These are the most common and typically the most cost-effective option. They connect a 'string' of solar panels to one inverter. If you have a straightforward roof without shading issues, a string inverter could be a solid choice.

Microinverters:

These are installed on each solar panel. They're ideal for homes with shading or multiple roof planes facing different directions as they allow each panel to operate independently. If one panel is shaded and its performance dips, the others won't be affected.

Power Optimizers:

Sitting between string inverters and microinverters, power optimizers are attached to each panel, like microinverters, but they work with a central inverter. They 'condition' the DC power before sending it to the inverter, making your system more efficient and less susceptible to production loss due to shading issues.

Your choice will depend on several factors: the size and shape of your roof, the amount of shading it gets throughout the day, and even the climate you live in. It's not just about picking the highest-tech option; it's about what works best for your home's unique situation.

In the next sections, we'll dive deeper into how to match these options to your needs, helping you get the most out of your solar investment

If you are looking for more details, kindly visit commercial inverters.

Factors to Consider When Choosing an Inverter

Selecting the right inverter for your solar system is more than just a technical decision; it's about maximizing compatibility with your panels, lifestyle, and energy goals. Here are the key factors to keep in mind:

System Compatibility: Your inverter needs to be compatible with your solar panel specifications. This includes the voltage and power output. An inverter that's not matched well with the panel specifications can lead to inefficiencies and even damage.

Efficiency: Look at the inverter's efficiency rating, which tells you how much solar power it can convert into usable electricity. Even a few percentage points can make a significant difference in your system's performance over time.

Size and Scalability: Consider the size of the inverter in relation to your current and future energy needs. If you plan to expand your solar array later, choose an inverter that can handle the increased load.

Installation Location: Think about where you'll place the inverter. Some are designed for indoor installation, while others can be installed outdoors. Environmental factors like temperature and humidity can affect an inverter's performance, so choose one that suits your environment.

Warranty and Support: A longer warranty period can give you peace of mind. Also, consider the manufacturer's reputation for customer support. You want a company that stands behind their product and is accessible if you need help.

Advanced Features: Modern inverters come with features like monitoring systems that let you track your energy production in real time. Decide which features are must-haves for you and which you can live without.

Cost: While it's not the only factor, cost is always a consideration. Balance the upfront cost of the inverter against the long-term benefits it will provide. Sometimes, spending a bit more upfront can lead to greater savings down the line.

Inverter Differences Explained

Understanding the pros and cons of each inverter technology is key to making an informed decision that aligns with your solar energy goals. Here's a breakdown to help you weigh your options:

String Inverters

Why they're a good choice:

Cost-effective: Generally less expensive than other types.

Proven technology: Well-established with a long track record.

Why you might think twice:

Single point of failure: If the inverter goes down, the entire system goes with it.

Shading impact: Performance can drop if one panel is shaded, as all panels in a string are affected.

Limited monitoring: Typically, you can't monitor the performance of individual panels.

Less flexible: Not ideal for roofs with multiple angles/orientations or shading issues.

Less reliability: Typically have 10-12 year warranties.

Not modular: Limits future upgrades.

Not as user-friendly: Sometimes difficult to size accurately to avoid power clipping.

Microinverters

Why they're a good choice:

No single point of failure: If one inverter goes down the remaining inverters and panels will work perfectly fine without interruptions.

Panel-level optimization: Each panel works independently, maximizing energy production.

Modular design: Easily add any number of panels to the system without swapping out any equipment.

Enhanced monitoring: Allows for monitoring of each panel's performance.

Better performance in shade: Ideal for roofs with partial shading.

Extended reliability: 25-year warranty.

Ease of use: Seamlessly pairs with solar panels to avoid power clipping.

Why you might think twice:

Higher cost: More expensive upfront investment.

Power Optimizers

Why they're a good choice:

Improved efficiency: Optimize DC power from each panel before conversion.

Shade management: Better performance than string inverters under shaded conditions.

Cost-benefit: Typically cheaper than microinverters but with some of their benefits.

Why you might think twice:

Must be paired with a string inverter: A failure in the central inverter affects the whole system.

Each technology has its place, and the best choice for you will depend on your specific situation. For instance, if your roof experiences partial shading at certain times of the day, microinverters or power optimizers could be more beneficial. On the other hand, if your roof has unobstructed exposure to the sun, a string inverter might be all you need.

Remember, the inverter is a long-term investment in your solar system's health and productivity. Weighing the pros and cons of each technology with your unique energy needs in mind will guide you to the right choice for your solar journey.

Installation and Placement

The proper installation and placement of your solar inverter are as crucial as the device itself. An inverter works best when installed in a location that balances exposure to the elements with ease of access for maintenance and monitoring. Typically, this means a spot that avoids direct sunlight, excessive dust, and any chance of flooding — think of a shaded side of the house or a garage wall. It's not just about protecting the inverter; it's about preserving its efficiency and extending its service life.

While the inverter should ideally be close to the solar panels to minimize energy loss, practicality may dictate otherwise. For instance, you might need to consider the length of cable runs, potential electromagnetic interference, and even local building codes that could influence the placement. It's a balancing act between the ideal technical setup and the constraints of your home's layout and local regulations.

The inverter needs to be mounted correctly — usually vertically — to achieve adequate cooling. Overheating is a common issue that can lead to inefficiency or damage, so proper ventilation is a must. And when it comes to maintenance, you'll want the inverter within easy reach. There's nothing more frustrating than needing a ladder or having to move obstacles just to perform a simple system check.

Given the technical and regulatory complexities, it's wise to have your inverter installed by a professional. Contacting an experienced solar installer will not only guarantee that your system meets all safety standards but will also optimize the placement for performance and longevity. Going with a reputable local installer can help make sure that your solar system operates smoothly from day one.

Reliability and Warranties

When investing in a solar inverter, understanding the reliability and warranty offered is as crucial as the inverter's technical specifications. A reliable inverter can secure consistent performance over the years, while a comprehensive warranty can protect your investment.

Modern inverters are designed with robust technology. For instance, microinverters and power optimizers are known for their durability, often outlasting string inverters due to their ability to operate independently, reducing the strain on any single component. The reliability of an inverter is also reflected in its design to withstand environmental factors, such as temperature fluctuations and moisture, which are critical considerations for outdoor installations.

Warranties for solar inverters typically range from 10-25 years and they can be a testament to the manufacturer's confidence in their product. Some high-end microinverters come with warranties that can extend up to 25 years, closely matching the warranty period of solar panels themselves. It's important to read the fine print and understand what the warranty covers. Does it include parts and labor, or just the parts? Is it a limited warranty that only covers certain defects, or is it more comprehensive?

When choosing an inverter, consider the manufacturer's reputation and the reviews from long-term users. A company with a solid track record in customer support and warranty fulfillment is as valuable as the inverter's efficiency and technological prowess. With Astrawatt Solar, you can expect guidance in selecting an inverter that promises both reliability and a strong warranty, giving you peace of mind with your solar investment.

Cost Considerations

As you consider the financial aspect of choosing a solar inverter, it's important to recognize that solar power is an accessible and wise investment, not just for the environmentally conscious but for anyone looking to take control of their energy future. With utility rates climbing at unprecedented rates, the traditional monthly bill is becoming a significant, never-ending expense. Solar energy, in contrast, offers a chance to break free from this cycle.

Choosing the right inverter can amplify the return on your solar investment. A more expensive inverter might offer better efficiency, a longer warranty, or crucial features that could save you money in the long run. A higher quality inverter means your system will work more reliably, for a longer period of time, with fewer or no periods of downtime ultimately increasing your production and increasing your ROI. On the flip side, the most advanced inverter won't add value if your solar setup doesn't require its specific benefits.

Think about the inverter's efficiency rating — higher efficiency could mean more electricity to power your home and less waste. Also, consider potential future savings from a model that offers expandability, should you decide to grow your solar array down the line. Getting a quote from a seasoned solar installer is the best way to get a clearer picture of the financial aspects.

Ultimately, the goal is to find a balance between quality and cost, ensuring you invest in an inverter that delivers reliable performance and fits your budget. It's about smart spending for sustainable savings.

Final Thoughts and Recommendations on Solar Inverters

As we reach the conclusion of our guide, it's clear that the right solar inverter is a cornerstone for any efficient and reliable residential solar system. Our recommendation is to approach this decision with an eye on quality and a perspective on the future. Opt for an inverter from a reputable brand that offers a solid warranty, and consider models that provide monitoring capabilities to keep you informed about your system's performance.

Don't overlook the power of peer reviews and testimonials. They are the collective voice of experience, offering unfiltered insights into how an inverter lives up to daily demands. They can highlight a product's strengths and expose any weaknesses, guiding you toward a decision that others have road-tested.In the end, choosing the right inverter is about finding a balance — a product that meets your energy needs, a brand that supports your journey, and a warranty that secures your peace of mind. With an installer like Astrawatt Solar, you can navigate this decision with expert advice, ensuring that your solar setup is as robust and reliable as the sun itself.

The company is the world’s best solar inverter manufacturer supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.