Solar panels produce DC power.
Your home appliances, on the other hand, run on AC.
That's why—besides the panels themselves—your solar system also needs devices called "inverters" to convert the DC power generated by your panels into usable AC electricity.
Recently, however, some manufacturers have also started producing related devices called "solar power optimizers."
Unfortunately, because they're so new to the market, there's still a lot of confusion about what power optimizers actually do—confusion which we'll be clearing up today
Power optimizers are NOT a third type of inverter
The first thing we need to get straight on is that—regardless of what you may have heard—power optimizers are not a type of inverter.
Inverters come in only two types:
Sometimes an entire array of solar panels is connected to a single high-capacity string inverter
Alternatively, each panel can instead be paired with its own small-capacity microinverter.
Though many online sources present power optimizers as a third option that eliminates the need for either string or micro inverters entirely, that isn't so.
A power optimizer does absolutely nothing in terms of converting DC power to AC and, hence, regardless of whether your solar system employs them or not, you're still going to need an inverter.
Microinverters don't just convert AC to DC
Power optimizers are similar to
microinverters in one respect: when they're deployed, each solar panel gets connected to its own individual one.
Moreover, though a power optimizer won't convert DC power to AC, that's not the only job that microinverters have either.
Microinverters also help to solve a problem that occurs when solar panels are placed on a roof that's partially shaded. Likewise when you've got panels on roof surfaces that face different directions.
In either case—if something isn't done—your solar system is going to be producing a lot less electrical current than it could.
Volts vs amps
A single solar panel won't produce much voltage.
That's why they're always wired together in series as opposed to parallel. Connecting solar panels in series makes the overall voltage of the system cumulative.
But, alas, there's more to an electrical current than its voltage. There's also its amperage.
Amperage measures the amount of electrical current passing a given point at any time. If we think of electrical current analogously to water current, amperage is like the volume of water flowing past a certain point.
Voltage, on the other hand, measures the amount of force pushing that electrical currentSo, along. It's analogous to the force propelling a current of water.
Shady roofs
Here's the problem:
While connecting solar panels in series does indeed increase the overall voltage by making it cumulative, it also limits the overall amperage to that of the lowest-performing panel.
That means major problems if some of your panels are getting shaded. Likewise, if your panels are divided between two or more roof surfaces getting different amounts of direct sunlight.
In either case, some panels will be getting significantly less sun than others for all or part of the day.
When that does occur, they'll also be producing less electrical current—aka, fewer amps—than their better-placed brethren.
And, once that starts happening—because they're all wired together in a series---the overall amperage produced by the entire system will be stuck at that level.
In other words: a single solar panel that's getting less sunlight than the rest will cause all the others to produce less current as well.
Microinverters are designed to solve that problem. Besides converting the DC output of solar panels to usable AC, they also regulate the output of each individual panel so that it's always performing at maximum capacity, regardless of shading or orientation.
Power optimizers
That's where power optimizers come in.
Before they emerged, microinverters were the only option if one or more of your solar panels gets substantially less sunlight than the rest.
Like microinverters, power optimizers regulate power output to ensure that underperforming panels don't limit the amperage of the whole system.
But that's all they do. So even if all your solar panels are outfitted with power optimizers, you're still going to need a string inverter to convert their DC power output to AC.
The possible advantage is that using power optimizers and a single string inverter can sometimes turn out to be cheaper than outfitting each panel with its own individual microinverter.
But either way, at least one inverter is going to be an essential part of your clean-and-renewable-energy-generating picture.