In solar energy, the function of an inverter is to effectively manage the way your solar system works. This includes maintaining the balance between the two types of energy involved in powering your appliances.
First, there’s direct current power, which is also referred to as DC. This is the type of power that you find in batteries, and it’s the same power that solar panels generate. However, DC energy on its own cannot be used to power your appliances, which is why you need an inverter.
Because all the electrically powered appliances in your home use an alternating current (AC), you need an inverter to convert the DC energy stored in the solar panels into AC power that you can use.
Off-Grid vs. Grid-Tied Inverter
How does a grid-tied inverter work? Well, it basically converts DC power that’s stored in the solar panels into AC, after which it sends it to the grid in order to obtain credit. Now, there are literally only two parts involved in wiring a grid-tied inverter, the inverter itself and your solar panels, which is why they’re so simple and easy to install and use. There are some grid-tied units that come with batteries nowadays but they’re still a rare find.
What about off-grid inverters, you ask? Off-grid inverters require a third component in order to function and that is a battery.
First, the solar panels transfer energy that’s still in DC form to the batteries, which the inverter inverts into AC power that you can use for all your household appliances. In a way, this system is sort of like a mini power grid, and the best part is that the inverter won’t use up the power in your batteries as the solar panels will constantly charge your battery bank.
Since they contain extra parts like a battery monitor, charge controller and AC/DC circuit breakers, off-grid inverters are significantly more complex than their grid-tied counterparts. Not only that, but you also have to account for the added off-grid equipment that you need to make the system work, including remote controls, surge suppressors, breakers and enclosures etc.
We understand that some of this terminology might be a bit confusing at first, but you need to get used with it so that you can understand the following information. It’s going to help you make an informed purchase when the time comes for you to buy a converter.
How Solar Inverters Work in a PV System
As soon as the sun hits the solar photovoltaic (PV) system, the electrons inside the solar cells shake about to create DC energy. Thanks to the circuits within those cells, enough energy is accumulated to power your home.
Solar panels collect sunlight and convert it into energy, and once that energy has been sent to an inverter, it gets converted from DC energy to AC energy. In this form, solar energy has the capacity and ability to power all kinds of appliances around the house such as the kettle, stoves, hair dryers and other electronics.
How to Choose a Solar Inverter
The following are a few important facts that you need to keep in mind before you purchase a solar inverter:
Check the Size
First off, consider the amount of power that you need to run your household. Determining the appropriate off-grid inverter size that’s right for your home is pretty simple and requires only that you make a list of all the appliances that you’ll be using around the house.
Then, calculate the wattage of all the different appliances and lights put together to figure out how many watts your system will need to generate in order to power everything at once. Of course, you probably won’t have everything running at the same time, but aggregating everything like this is the best way to get the most out of your solar system.
Remember to include the voltage that each appliance requires to run smoothly. The average appliance typically runs on 120Vac, whereas something as complex as a well pump might require up to 240Vac.
Consider Pure Sine Wave Instead of Modified Sine Wave
We won’t go into how pure sine wave inverters work in this article, as that would require a whole other post. However, we can tell you that they provide a cleaner power output than a modified sine wave inverter.
However, some people opt for modified sine wave inverters anyway because they’re a much cheaper option but they end up with low-quality power output as a result.
Pure sine wave inverters, on the other hand, provide excellent quality power output that’s comparable to a power grid (and in some cases even better).
Also, modified sine wave inverters have been known to negatively affect the performance of certain appliances like pumps, compressors and motors that just wear out quicker than they’re supposed to. It can also damage computers to the point of complete breakdown, while TVs and radios often end up with static background noise or develop poor audio and video quality.
That’s why we highly recommend that customers go for pure sine wave inverters to avoid these and other problems. Even if you have to save a little more for them, it’s worth the wait because you know they’ll help extend the lifespan of your appliances.
If you want to know what the difference is between a pure and modified sine wave inverter, simply look at its total harmonic distortion (THD) rating. This is usually written on the inverter’s spec sheet and tells you what the power quality output of the inverter is.
Look at the Technical Specs
The following is a list of important technical specs to look out for when making your purchase:
- Efficiency – This basically refers to the maximum amount of battery power that the inverter will be able to deliver to your home appliances. Ideally, you want your inverter to have a maximum efficiency rating of 94% to 96%.
- Self-Consumption or No-Load Current Draw – Even when it’s sitting on standby, your inverter will continue to consume power. For the best results, make sure you go for an inverter that has low power requirements.
- Surge Capacity – No matter how efficient your system is, short-term overloads can happen. You need an inverter that has a high surge capacity so that it doesn’t trip when this happens. Also keep in mind that certain appliances like the fridge require up to 3x of their normal energy requirement to even power up.
- Battery Charger Output – A thoughtfully designed off-grid inverter should come with its own battery charger that you can use along with a backup generator to keep the lights on during the cold winter months. The battery charger for a solid quality off-grid inverter will have a rating of about 50-100 amps DC to keep you going.
- Temperature Range – Whatever you do, don’t store your inverter in an area that experiences extreme temperatures because they are very sensitive to extreme heat.
- Warranty – The standard warranty period for an inverter starts at one year, but this can go up to 3, 5 and even 10 years if the manufacturer is willing to provide an extension.
If you want to find out how your inverter measures up based on the above mentioned technical specs, simply look at the product’s spec sheets, or consult with a specialized solar technician to help you choose a good quality inverter.
Depending on the inverter you end up choosing, you may need to purchase a few extras, such as:
- Battery Charger – This will keep your system running even when there’s no sun for your solar panels to draw energy from. These can also double as inverters when needed, and they work by drawing power from a backup AC generator.
- Grid-Tied Capability – If you’re considering a grid-tied setup with backup battery power, then it might be worth it to consider a grid-tied inverter with the ability to send power to a central grid.
- Automatic Generator Start – While this particular function comes as a standard feature of some inverters and charge controllers, yours might require one that comes as an extra attachment.
- Read Up on the Manufacturer – To make sure that the product you’re purchasing is of high quality, do your research on the manufacturer and find out what kind of reputation they have. At the end of the day, inverters are a long-term investment that you should purchase from a reliable manufacturer.
- Check for UL Listings and Certifications
For the purposes of code compliance and safety, off-grid inverters need to be certified according to the law.
For example, home inverters require a UL 1741 listing, while boat and RV owners need to carry a UL 458 for their mobile inverters.
Inverters that are used for emergency purposes require a KKK-A-1822E certification, and you’ll need a UL 1778 in order to enjoy uninterruptible power supply.
If you’re outside of the US in a place like Canada, you’ll need to have a CSA 107.1 standard certification, and for those outside of North America, there’s the IEEE 1547 standard certification which is internationally recognized.
Check the Price
As with anything that you purchase, the price will play a huge role in the type of inverter that you choose, and of course, you get what you pay for. Oftentimes, the pricier a model is the more features it has.
Also consider the price of the components required when installing the entire system, including circuit breakers, mounting plate, remote control etc., and don’t be afraid to shop around to compare prices too!
Solar Inverter Types
A solar inverter is designed similarly to a LEGO toy and it comes with different pieces that need to be put together to make it work. Also, they’re designed so that you can attach them to a certain amount of solar boards, and these solar boards usually cost 90% more than the inverter itself.
Unlike your solar panels, which can last for up to 25 years, inverters are designed according to the principles of planned nascence, which means that they’ll have to be replaced after a predetermined number of years. To get the most out of your solar inverter, be sure to plug it into the right quality and quantity of solar panels.
If you connect it to more or less solar panels than required, it may malfunction or simply fail to perform at its highest capacity. For the best results, make sure that you inverter stays connected to about 95% of the solar panels that it’s supposed to be hooked up on at any single time.
The following is a list of the 3 different types of inverters available on the market:
Standalone Solar Inverter
As the name implies, standalone inverters work regardless of whether or not they’re connected to a solar panel. They’re able to source power in DC form from photovoltaic (PV) batteries, wind turbines, hydro turbines, and engine generators.
The market is flooded with standalone inverters, and it’s probably because unlike their tied-up counterparts, they don’t need anti-islanding protection. Also, they work constantly to integrate vital battery charges, which help keep the AC battery charged up.
Grid-tied inverters work together with a utility charged sine wave and are an ideal option if you want to power your home with a utility grid that will let you benefit from net metering.
On the other hand, grid-tied inverters are designed to automatically switch off whenever there’s a power cut, which pretty much makes them useless in times of emergency.
If you’re considering this option, keep in mind that grid-tied inverter systems require anti-islanding protection. A grid-tied inverter is said to experience islanding when it functions as though the utility grid is functioning even when it isn’t. This usually happens when the electrical system has resonating load circuits.
Battery Backup Inverters
A battery backup inverter works by siphoning energy from the batteries using the onboard charger to manage that energy charge, and then delivers the excess energy to your utility grid. You can use these to deliver AC power to specific areas during power outages. Also, they require anti-islanding protection when you install them as well.
Top 5 Best Solar Inverters Of 2018
Solar inverters are an important component for your solar power system and are vital to ensuring that everything runs like a well-oiled machine. Below we’ve listed a few of what we consider to be the best inverters available on the market, as well as the pros and cons of each so that you can make an informed decision.
APS YC500A Micro-Inverter
This efficient micro-inverter from APS boasts features like integrated ground and a highly capable trunk cable. Although small, this unit has the capacity to handle a sequence of 16 solar modules with a 20A breaker.
Plus, it has an impressive power output that can reach up to 500W. All in all, this APS YC500A Micro-Inverter definitely lives up to the phrase “dynamite comes in small packages.”
- Has the ability to function with multiple modules
- Great design
- Nice and compact
- It’s a bit delicate so you have to be careful with how you handle it
GIANDEL Power Inverter 12000WATT
If you’re shopping on a budget but you still want a good quality inverter, this is it. Designed by Australia’s leading inverter manufacturer GIANDEL, this inverter comes with dual AC outlets and a convenient USB charging port.
It’s designed in a way that the input and output spots are isolated, which makes it really safe to install and keep.
You can use this to power up your laptop, a few lights, some power tools etc., at the same time without it tripping.
- Manufactured by a reliable brand
- Backed by a 1-year warranty
- Comes with lots of awesome features
MicroSolar 12V 3000W Heavy Duty Inverter
This well-built MicroSolar 12V 3000W Heavy Duty Inverter effortlessly connects to your panels to provide 92% conversion efficiency.
Sure, it’s large and clunky, but that’s what makes it so tough, and it’s backed by a 1-year warranty and a 6-month free replacement.
- Has 300W power capacity
- Powerful and won’t trip
- 120V AC output
- Built tough to last
- This model doesn’t really come with a lot of features
- The warranty period is rather short
AIMS Power 6000 WATT 24V DC to 120/240V
Now, if you’re on the market for a really sturdy, powerful and capable inverter that will last you for years, look no further than this 600W unit from AIMS.
With a peak power capacity of 18000 watt, it only makes sense that this inverter features an industrial/ marine grade frame. We also love that it’s packed with useful features, like settings to let you choose the battery type, auto gen start, a charge controller and even a built-in smart battery charge.
- It could use some improvements in the looks department
OutBack Power VFX3648 Vented Off Grid Inverter 3600W 48VDC
This particular inverter yields high wattage for when you want to power several appliances and lights in your home at the same time. It’s ideal for hot and humid areas thanks to its bug-proof screen windows, which means that you don’t have to worry about mosquitos messing with your power supply during hot weather conditions.
- Perfect for an off-grid setup
- High wattage yield
- It’s quite pricey
With the right solar inverter, you can enjoy a smooth functioning and powerful solar power system that won’t trip due to overuse, and will come in handy during emergency power outage situations. As mentioned above, you want a solar inverter that comes at a good price point with all the right features and specs.
Of the inverters we reviewed above, we believe that the GIANDEL Power Inverteris the one with the right combination of power, ease of use and installation, as well as a good balance of features. It boasts 12000Watts of power, two AC outlets, a dedicated USB charging port, as well as isolated input and output spots.