What are DC power optimizers?

DC power optimizers are electronic devices housed in small plastic boxes under each solar panel in an array. They ensure each solar panel in an array is producing power at its maximum potential.

Power optimizers work in conjunction with a central string inverter, which converts the DC power output of solar panels into AC power that can be used in your home. A string of solar panels in an array without power optimizers can suffer low power output when only one panel is shaded.

If you have partially shaded conditions or need to install with multiple orientations to the sun, power optimizers can be a smart option and may be a better fit for your needs than microinverters. While microinverters solve the same shading and roof orientation problems as power optimizers, they are more expensive to install.

There are several advantages and disadvantages of power optimizers to be aware of as well. We’ll cover them all below.

How power optimizers work

When the sun hits a solar panel, it creates DC electricity. When panels are strung together, all the DC power usually gets sent along to a central string inverter. The inverter converts the power into AC electricity your home appliances use. 

This setup works very well for a majority of solar system setups. However, if you have a roof with partial shading issues or multiple orientations, your power output will suffer. That’s because the production of the string of panels is limited by the performance of the worst performing panel. 

In the challenging solar installation conditions outlined above, the maximum power you can create with each panel varies. That’s because the amount of power each panel generates depends on temperature, amount of sunlight, and special characteristics of the power load. When panels face multiple directions or some are shaded, these factors differ across the array. 

Power optimizers account for this problem by using a technology called maximum power point tracking (MPPT). Smart researchers figured out that if you can track the maximum power of each panel in real time, then smooth and condition the electricity each panel generates before sending it along to the inverter, your inverter can process much more electricity. 

To do this job, power optimizers are affixed to the back of each individual solar panel in your array. They turn individual panels into smart modules by tracking their peak output and regulating their voltage before sending the power along to your central inverter. 

The result is optimized performance for every single panel in your solar system, regardless of orientation to the sun, shade, or even damage to one or more of the panels. 

SolarEdge is a leading manufacturer of power optimizers, we’ll cover some of their system specifications below.

If you have a challenging roof which has multiple orientations to site panels on and have shading issues to contend with, power optimizers are a smart solar installation choice. 

There are several benefits and a few drawbacks to DC power optimizers to be aware of. We cover them below so you can be well-informed on these important considerations and can confidently proceed with your solar system design. 

Advantages of DC optimizers

Power optimizers have several advantages over other grid-tie inverter systems like microinverters. Here are some of them to consider: 

More efficiency in partially shaded conditions

As outlined in the summary above, DC power optimizers allow you to harvest significantly more electricity when your panels are partially shaded or facing multiple angles. In fact, according to SolarEdge, you can expect up to 25% more power with the help of DC power optimizers. 

If you are looking to install solar and know your array will be partially shaded through the day, power optimizers are a good idea. 

Individual-level panel monitoring

Power optimizers are a type of module-level power electronics (MLPE). They are able to collect and feed solar energy production data like output voltage and peak efficiency from each PV module to the cloud, reporting financial and power performance data back to you in a real-time app. 

It’s a smart tool, as you can get notifications for when and if your system isn’t performing as well as it should be, based on the current weather conditions. That way, you can alert your installer to check up on your system to make sure everything is working correctly.

DC-coupled battery options

Since solar panels and batteries both operate in DC electricity, it makes a lot more sense to feed the DC energy output from your solar panels directly to your battery storage. 

This way, your system will be way more efficient, since you don’t need to convert electricity to AC, then back to DC voltage for use in your battery. 

SolarEdge makes a DC-coupled smart charging solution called StorEdge to route electricity from your power-optimized panels directly to your battery. That exchange happens before your inverter converts the power to AC electricity for your home use. 

This ensures you get the most value from the electricity your solar panels produce in your battery backup system.

Smaller inverter size

Since the voltage tracking and cleaning happens at the individual module level, the inverter tied to power-optimized solar modules doesn’t need to be as bulky. This can free up some space around your garage or home exterior wall and be more aesthetically pleasing to you.

If you don’t want any inverter taking up wall space, you might want to explore installing microinverters instead of power optimizers.

System oversizing 

The SolarEdge StorEdge system allows you to connect a much larger-sized solar array to your inverter. The reason you’d want to do this is to take advantage of more power performance in low light conditions like dusk and dawn. 

When the sun is low on the horizon, your extra solar panels can still harvest near peak electricity. That means you’re potentially sacrificing some solar electricity during the middle of the day because your inverter can’t efficiently convert all of the available solar energy at that time.  

However, if your utility is on a time-of-use billing structure, evening electricity is most valuable. If you can generate more power at this time of day, you can reap more financial rewards.   

Your PV system needs to be carefully designed to best take advantage of this scenario. Inverters are meant to convert AC power at a level which can’t be exceeded. So, if you’re generating a whole bunch of DC power with your panels, your inverter will limit the production of your panels to the amount of AC it can actually convert.  

Too much electricity routed to your inverter can also shorten its lifespan. Make sure to work with a reputable solar installer who can ensure you’re getting the most out of your solar equipment, without putting it at risk.

Disadvantages of DC optimizers

Here are several drawbacks to power optimizers to take into account when selecting your inverter system setup. 

Limited inverter selection

Power optimizers are relatively new to the market. Since SolarEdge is the only real manufacturer at the moment, you cannot use other brands of inverters to pair with their power optimizers. 

This means that power optimizers and SolarEdge inverters are meant to work in tandem with each other. 

If you don’t have any shading issues to account for, you may be better off selecting a much more affordable string inverter like the SMA Sunny Boy and avoiding use of power optimizers altogether. 

Cost

Since power optimizer equipment is installed on every single solar panel, your installation costs are going to be slightly higher than a traditional string inverter solar panel system. 

The average estimated price increase on a 6kW system over traditional equipment will be $300. When compared with more expensive microinverters, this cost increase is pretty minimal, but still worth mentioning here.

Differing warranty lengths for equipment needed

Power optimizers are relatively new technology, and SolarEdge is confident that they will last at least as long as your solar panels will. Standard warranties are 25 years, the same as most solar panel manufacturers. However, the inverter your power optimizers are tied to have warranties that last only between 8 to 12 years. 

This can be frustrating, as you may have to plan to replace your inverter before your panels. SolarEdge does offer an extended 20-year warranty on their inverters, which we recommend looking into for added peace of mind.

DC optimizers vs. microinverters

	DC power optimizers	Microinverters
Cost	Moderate	High
Ease of system expansion	Challenging	Very easy
Lightning risk	Low	Moderate
Panel-level monitoring	Yes	Yes
Performance with multiple roof angles	Excellent	Excellent
Performance in shade	Excellent	Excellent

Power optimizers solve the same basic challenges as microinverters. 

When installing solar panels in partially shaded areas, or when there are differing roof pitch angles to contend with, both solutions allow you to reap the maximum benefits of each individual solar panel’s contributions. 

They both allow you to monitor the performance of individual solar panels, as well.

Unlike string inverter setups, with a power optimizer or microinverter, your power output will not rely on the performance of the weakest producing panel. 

So, if a battalion of birds decides to relieve themselves on one of your panels, any panels which didn’t get bombarded with poop will still be able to pass 100% of their electricity output along to your home appliances or energy storage bank. 

Microinverters allow you to more easily expand the size of your solar panel array down the road. That’s because they do not rely on the size of a central inverter to convert electrical energy from DC to AC. 

Instead, that transformation happens behind every single panel. Therefore, you can easily plop down as many more panels onto your array as you like at a later date and enjoy enhanced electrical production. You can also free up some wall space, since there’s no need for a central inverter when you use microinverters.

However, microinverters are more expensive to install than power optimizers. They are also bulkier, with more complex circuitry than power optimizers. The added amount of technology up on your roof can mean more potential for your structure to be hit by lightning strikes. 

Final thoughts

DC optimizers inverters are a great option for solar systems with challenging installation considerations like shade or multiple roof angles. They allow you to harvest significantly more electricity under these conditions at a price competitive with traditional string inverter setups. 

DC optimizers have an advantage over microinverters, in that they cost less, perform a similar function, and route power to a central inverter instead of relying on multiple units which may fail or be difficult to monitor and repair.  

For more thoughts on deciding which type of solar inverter system is right for you, visit our guide to choosing the best solar inverter for your home. 

As always, if you are confused or are looking for more clarification, we recommend connecting with our network of solar installers to offer guidance and provide you custom savings estimates.