As you all know by now, an inverter is a significant purchase. The life of your electrical appliances in your home, such as the fans, tube lights, laptop, and even your television set, depend on it. A good inverter powers your important electrical appliances during a power failure. It also helps to power certain items such as a laptop or TV monitor that you wish to use inside your car.
There are many uses of an inverter, but before we get in on that, you need to look at some of its significant features.
1. What’s Your Power Requirement?
The power requirements of your home or office dictates the size of inverter you want to use. This is the total load you want to run on your inverter as backup. This is the most essential factor to take into account because an inverter is a pure power backup solution for your space. So any misstep in terms of calculating power can lead to a power failure.
What kind of electrical appliances are you planning on running at the time of power failure? This is the addition of all electrical appliances you want to support. According to studies, here is the general power requirement of the most basic appliances. (1)
- Fan – 75 watts
- Coffee maker – 1400 watts
- Desktop computer – 450 watts
- Dishwasher – 1500 watts
- Electric heater fan – 3000 watts
- Fridge – 400 watts
- Internet router – 15 watts
- Microwave – 1700 watts
- Television – 100 watts
- LED light bulb – 10 watts
- Standard light bulb – 100 watts
Say you have 5 ceiling fans, a couple of standard light bulbs, one computer, a television, and a fridge. These are all the electrical appliances you want to support during a power failure. This amounts to a total of around 1,600 watts of power requirement.
You can set your total load based on the number of hours you want to backup. This can potentially lower the number of electrical appliances you choose to backup, leaving you with only basic power requirements.
For example, if you want to backup for at least 6 hours, selecting low-powered appliances is idea. Say you take into consideration 2 ceiling fans, a couple of standard light bulbs, and a television. This amounts to 300 watts. Multiply the load by 6 as the power requirements of an inverter is per hour basis. The total load requirement would 1,800 watts for 6 hours. This would mean you need a total of 1.80 kilo watt hour units of electricity from your inverter.
This calculation may seem complicated, so you can use this handy power calculator here. It offers power consumption data based on standard power ratings of typical household appliances.
2. Choosing The Right VA Ratings
Based on your power requirements can you determine the right VA rating of an inverter. VA stands are volt ampere rating of an inverter. It is the total amount of voltage supplied by the inverter for a group of appliances.
The best way to determine the right VA rating is to divide the total power requirement in watts with the power factor of your home, which is generally 0.8.
From the example given in the previous factor, your total load or power requirement is 1,800 watts. So 1,800/0.8 = 2,250 VA
So buying an inverter with 2,250 VA is the right choice for your needs.
All things considered, the VA rating of any inverter will always be higher than the power requirement measured in watts. This ratio of the power requirement is known as the power factor. Which, according to multiple studies, is the only way to determine the VA rating of an inverter.
For simpler homes, the ideal power requirement isn’t any higher than 650 watts, which means the required VA rating for a suitable inverter is around 800 VA. The best suited inverter for this power rating is 900 VA. It is durable and efficient enough to power through all typical appliances such as the fan, tube lights, and an internet router. (2)
3. Considering Battery Size
When considering battery size, the only factor to look for is the Ah value. The Ah value of a battery dictates the amount of energy a battery can store. The most common Ah values of a battery are 100, 120, 150, 180, and 200 Ah. The higher the Ah value, the stronger the battery is.
A total backup of power for 6 hours 2,250 VA, so the battery value for that particular inverter should be 180 Ah. This is the simple setup that lets most consumers buy the best inverter of their choice.
All things considered, the performance of any inverter ultimately dials down to its battery. If the battery is low powered, it doesn’t have the adequate amount of energy to run various electrical appliances during a power failure. So when considering battery size, you need to ask yourself the following questions:
- How much backup or power support can an inverter provide?
- And for how much hours can it power certain appliances during a power cut?
The Ah value of a battery stands are ampere per hour basis. So if your VA rating for one hour is 500 VA then for 4 hours it would be 2,000 VA. This divided by 12 is 166 Ah, which is the total battery size of your inverter. Sounds simple, enough?
The second aspect of a battery that some of you might find helpful is choosing a single or double battery inverter. A double battery inverter has the same Ah value x 2. Since standard inverter batteries are not more than 200 Ah, if you need more power backup for your appliances, looking for a dual battery deal is a good choice.
Deciding on a durable battery plate is also important. Lead inverter batteries are available in either flat plates or tubular plates. The former kind is more suitable for shorter power cuts with a smaller small life cycle. While the latter is made of taller containers which makes it long-lasting, more durable, and efficient to use.
In places where longer power cuts are expected, companies offer tubular plate batteries for longer design and performance life. (3)
4. Different Types Of Inverters
There are 3 main types of inverters available in the market. They are Sine Wave, Modified Wave, and Square Wave inverters. Among these three, the most commonly used ones are Sine Wave and Square Wave inverter. But let’s look at each of them to better understand the workings of an inverter.
Sine Wave Inverter
A sine wave inverter is the most common inverter to purchase from a local utility company. Sine wave inverters are powered by rotating AC machinery. They’re easy to purchase, repair, and replace in case of damage. All sine wave inverters are designed with specific parts and designs, making it easy on you to buy extra equipment.
Many high-powered microwaves and motors are generated by sine wave technology, which promises long-lasting power and efficiency. If you’re looking for a standard generator that outperforms with full output of power, this is the ideal choice for you. (4)
However, sine wave inverters are more expensive than other generators on the market.
Square Wave Inverter
Only few square wave inverters come with an expensive price tag. They are the cheapest and most reliable inverters to look forward to. Because of its cheap price, a square inverter can power universal motors only, and nothing less. They offer basic features and performance for a cost-effective price. This makes it one of the most best-selling inverters in typical households.
Modified Wave Inverter
A modified wave inverter supports appliances like motors, lights, pumps, and fans. They have a waveform like a square, but a bit more slightly modified. These type of inverters offer speed efficiency and power, but for appliances that are not as demanding.
Such inverters are generally noisy than sine wave inverters. They produce a slight humming noise or buzz when powering multiple appliances. In any case, using a modified wave inverter for low powered appliances seems like a good fit. You also get variable speed control, which is a major advantage. (5)
5. Checking The Power Ratings
What’s the power ratings for your inverter? Traditional and modern inverters are available in all size ratings, arising from 50 to 50,000 watts. If you have a larger family, using an 11,000 watts inverter is the ideal choice. The same applies to PV systems.
What is the maximum surge? Surge is a term coined for all inverters that measured the total power usage in a number of seconds. All standard inverters, including high-end ones, come with continuous rating and a surge rating. The maximum surge of any inverter dictates how much of an overload that particular inverter can handle for a short period of time.
Based on the brand, build, and type of inverter, the maximum surge rating of an inverter differs. Once you start hunting down different surge ratings, you will find inverters that offer 20% up to 300% surge.
According to research, the standard surge rating for an inverter is from 3 to 15 seconds. This should work for most electrical appliances.
Inverters with low surge rating offer high-speed electronic coverage. Which makes them the most common type of inverter on the market. And also the cheapest. Such inverters usually offer around 25% to 50% of maximum overload. All brands offering inverters from 50 to 50,000 watts come within this surge range.
More importantly, the kind of inverters that can pump up to 300% surge overload, but for a short period of time, are lighter units with a slower peak capacity. These are generally much more portable and compact in design.
6. Don’t Forget The Warranty
It shouldn’t come as a surprise to you that choosing maximum warranty for your inverter is necessary. Without it, your inverter is most likely to fail after a short span of use. Higher and better warranties indicate a long-lasting battery life, energy efficiency, and accuracy. It also means that your inverter is made up of superior and durable materials.
Most inverter brands offer warranties that allow you to send back a model for service repair and maintenance, on a regular basis. This is important because it increases battery life and backup support. Back in the days, inverters were manufactured without batteries, which meant that different brands manufactured batteries while different brands manufactured the inverters. But due to the advanced in technology, most reputable brands offer an inverter-battery combo with higher warranties.
This means that your inverter is well-suited to work with the battery that powers it. This reduces the risk of complete power drop or inefficiency in performance during a power cut.
What’s also important is the inverter’s ability to withstand unexpected power failures at a relatively low battery charge. Even though regular maintenance is needed for inverters, buying an efficient inverter with higher warranties guarantees support and service.
Some inverters come with warranties and guarantees. For example, an inverter has a performance guarantee of 3 years and a warranty of 2 years. This is a guarantee and warranty of the performance of the inverter’s battery. What this dictates is that in case of replacement, it is under the manufacturer’s expense for 3 years. And in case of repair, it is under the manufacturer’s expense for 2 years.
This also illustrates the clear difference between an inverter’s guarantee and warranty policies. Almost all modern inverter brands offer such support, which is a good thing for new customers. On the other hand, you will find certain manufacturers offering only warranty and a disclosed replacement period under the expense of the brand. For this you have read all the manufacturer’s policies regarding repair and replacement.
7. Do You Need Inverter Protection?
Overload protection is also known as lightning protection from overvoltage strikes during bad weather. Opting for extra lightning protection for your inverter is important if you live in areas where storms and bad weather is expected. Inverter protection is important because it also reduces overheating, overvoltage, and overload shutdown during emergency situations. (8)
What this kind of protection does is it creates a durable layer between the metal installations and wiring of the inverter. This prevents water from entering inside the inverter’s components and avoids any risk of a lightning strike.
Some of you may have read about “surge protection devices” which are designed to keep such generators safe and efficient, even during a storm. The whole point of buying surge protection for your inverter is for maximum security and power backup during a power cut. Such devices offer just that, and much more. (9)
Broad protection (SPD Type I)
This type of protection offers the highest value and feedback for current resistance. They can handle direct lightning strikes. The costs of using such type of surge protection is low, however you can easily find models of higher value based on the type of inverter you buy.
Some manufacturers offer SPD protection along with an inverter, at a relatively higher price.
Medium protection (SPD Type II)
This type of protection offers a moderate level of current resistance from lightning strike. But the difference is that it is only to protect against indirect lightning strike, unlike broad protection. Inverters protected with SPD Type II are often safe from high overvoltage strikes. They’re comparatively cheaper in price, but are as long-lasting and efficient to use.
Fine protection (SPD Type III)
This type of protection offers the least possible current resistance against lightning strikes. These protect inverters against lightning strikes that occurs a distance away from your home. While they protect highly-sensitive electrical devices, they protect against residual overvoltage even during bad weather.
Looking After Your Inverter
It’s important that you understand the various safety features of an inverter before using it to backup other appliances. While most inverters come with surge protection and overvoltage protection, knowing how safe and efficient inverters are, based on these features, can reduce risk of shutdown or any damage. (10)
Low battery voltage alarm
To ensure your inverter doesn’t unexpectedly run out of battery, it’s good to opt for a low battery voltage alarm. Such an alarm system will help you keep track of your battery capacity before it discharges completely. Certain alarm systems come with programmable reminders that let you know how long before the battery dies completely.
Low battery voltage shutdown
As opposed to a low battery voltage alarm, a shutdown is when an inverter automatically stops working when it reaches a certain voltage. For example, if the inverter discharges down to 15V, it automatically shuts down. And you can only use the battery again when you connect it to another battery with a higher than 15V current.
Just like any other powerful battery, inverters produce heat when in use. For this reason, protecting the inverter from heat build-up is very important. The first thing to do to protect against overheating is to place the inverter in a spacious area. Keeping the inverter cramped will increase heat production which can lead to many kinds of damages.
The second thing to look for is overheating protection that is built in an inverter, as a reliable feature. Many brands offer overheating protection features that turn the inverter off as soon as there’s an increase in heat capacity or temperature.
As mentioned in the previous factor, overvoltage protection is important for all kinds of inverters. This is during unexpected weather conditions, especially during storms or lightning. Another kind of overvoltage protection is when the inverter shuts down automatically when the battery life exceeds a certain voltage in order to protect the electrical appliances that are supported by it.
AC output overload protection
A short circuit is a common phenomenon which can potentially harm your inverter and other appliances. The AC output overload feature shuts down an inverter as soon as it produces too much AC electricity. It first stops backing the electrical appliances and later it shuts down the inverter to prevent a short circuit.
Moving forward, here are some ways to increase battery life of an inverter.
- Some inverters come with distilled water support which needs to be replenished once every 3 months. You can set a reminder on your phone or on your kitchen calendar to check the inverter once every 3 months.
- The surge connections on an inverter keep the battery and other wiring from rust or debris build-up. The best way to maintain the connectors on the inverter is to coat them with grease. In case there is corrosion on the socket of the connectors, combine warm water with baking soda and brush out the difficult rust spots.
- For short-lived inverters, re-charging the battery once a month to maintain its inner electrolyte condition is also important.
- Overloading your inverter with high-powered appliances is a complete no-no; even if you have a maximum surge inverter. Staying energy efficient during a power failure can positively impact the battery life of an inverter.
This is what you need to know when choosing an inverter. It’s not a simple buy, I know it and now you do too. Newer models of inverters come with better warranties, terminal protection, and materials. They even offer higher power ratings to support appliances like a refrigerator, computers, and dishwasher for a long period of time.
You can even buy an inverter based on the number of hours you want to use it for. All this is possible only after considering significant factors of an inverter. For example, the power requirements of multiple appliances dictate the power voltage use of an inverter. This is true when you need an inverter for your home or commercial setting.
The power consumed by 5-6 appliances can easily be backed up using a single battery inverter. But if you’re looking for anything more than 2,000 VA, opting for a double battery inverter is essential. All things considered, you can only make the right decision based on the right features.
Jen Miller is a former electrical engineer and product specialist with more than 20 years of product design and testing experience. She has designed more than 200 products for Fortune 500 companies, in fields ranging from home appliances to sports gear and outdoor equipment. She founded Jen Reviews to share her knowledge and critical eye for what makes consumers tick, and adopts a strict no-BS approach to help the reader filter through the maze of products and marketing hype out there. She writes regularly and has been featured on Forbes, Fast Company, The Muse, The Huffington Post, Tiny Buddha and MindBodyGreen.