What’s The Best Inverter For High Power Solar Panels?
High power solar panels only perform as well as the inverter they’re connected to. Choosing the best inverter for high-efficiency solar panels is the most important decision you’ll make when going solar, yet solar shoppers often overlook it.
While SolarEdge inverters have more flexibility in sizing the output to match the solar panels, the central inverter unit is a single point of failure. This makes Enphase microinverters the best inverter overall for solar panels. But what about solar panels with high power output like 400 watts?
For high-power solar panels, opt for the Enphase IQ7A series or the SunPower SPWR-A4. These are the highest capacity microinverters made for high-wattage solar panels. Both the IQ7A and the SPWR-A4 have a continuous output power of 349 VA, and the maximum is 366 VA.
How Much Solar Power Does The Inverter Allow?
When reviewing solar proposals, consider the DC power produced by the solar panels and how much AC power the inverter can output. These amounts are rarely equal, but clipping and power loss will occur if the panels produce much more power than the inverter can output.
What Is Clipping And Why Does It Happen?
When an inverter can’t convert and output all of the power that a solar panel produces at peak hours, then power is lost. Visually on solar monitoring, it flattens the top of the bell curve and is known as clipping since power can’t flow through the inverter.
This will happen when you use Enphase IQ7 or Enphase IQ7+ with solar panels higher than 350 watts. The IQ7 allows for 240 VA and the IQ7+ allows for 290 VA maximum. Using these microinverters with solar panels in the 400-watt range is not good design practice.
How To Properly Size Your Inverter To Your Solar Panels
Understanding the three different sizes of a solar system makes it easy to know if your inverter is properly sized to your system. You’ll avoid lost or clipped power, and also reduce unnecessary costs of buying high power solar panels that are too powerful for your inverter.
Solar PV Systems Have 3 Ratings or Sizes
When I send the Net Metering Agreement to my solar customers, many of them think I made a mistake in filling out the application. “I have a 7.2 kW system, why does the application say it’s 6.5?” And “Why is the system nameplate rating only 5.8?” It’s because solar systems have 3 ratings or sizes: DC rating, AC rating, and the Nameplate rating.
Why is my PV module rating larger than my inverter rating?
Solar panels capture and output power in DC, just like AA batteries do. The DC rating is what your salesman presents to you. Your home, however, uses AC power, as does the utility company. Inverters convert DC to AC power, and there’s approximately 10% loss in the conversion. So a 5.55 kW DC system is approximately 5.0 kW AC.
DC Power, AC Power, & Inverter Nameplate Rating
Since utilities operate in AC power, that’s what you see in your NEM application. You may also see the “Nameplate Rating” or inverter maximum capacity. This is the max amount of power your inverter can output. If it’s significantly less than the DC or AC size of your solar, then you will have clipping. It’s as easy as that, knowing your inverter nameplate rating and comparing it to your DC & AC rating. Your salesman should be able to provide you with all three.
Do Micro Inverters Clip More Than String Inverters?
Both micro inverters and string inverters can clip if they are undersized compared to the solar panels connected to them. The difference is that with a string inverter, we measure by the array size connected to it, and with micros we measure by the panel since each has its own inverter.
The capacity of a micro inverter determines how much power can flow through it from a high power panel. Microinverters come in limited sizes, so clipping is much more common with them.
Micro Inverter Clipping
Simply put, if you have a 360 watt panel, and the Enphase micro inverter’s max capacity is 290, you will see clipping when the panels produce their maximum power, typically mid-day.
String Inverter Clipping
If you have an 9.5 kW DC solar system, and the string inverter is a SolarEdge 7600 capacity model, you will see clipping if all the panels hit max capacity at the same time. If half of the panels point east and the other half west, clipping may not occur. String inverters have greater power capacity, but an installer can still undersize them to the solar array. This is called overclocking.
Why would a solar installer use inverters rated at 70% of the panels’ output?
This is an important question for your installer if they’ve overclocked your inverters. Installers will argue that panels rarely output their maximum power and degrade over time. Cost may also be a consideration. If they undersized it, ask them what justifications they used. If your goal is to maximize system output, then picking the inverter that best pairs with your choice of panel is important. Let them know it matters to you.
Clipping rarely results in more power no matter how many charts or simulations they show you, and almost always results in less overall generation. That means clipping costs you money over time, and any cost savings gained by using cheaper inverters is nullified.
Using a lower capacity inverter can be justified when the electrical service panel isn’t suited for higher capacity inverters. If that’s the case, also consider reducing panel wattage so power isn’t lost to clipping.
What Is The Optimal Inverter For My Solar System?
In my post about the best solar inverter, I outlined why Enphase is the best inverter, in spite of clipping. Clipping can be avoided if you’re aware of what causes it.
Why Enphase Microinverters are generally the best solar inverters:
- Manufacturer’s 25-year warranty
- Easily expand your solar system if needed
- Highest shade tolerance
- Design flexibility
- No single point of failure
- Aesthetically pleasing
- Robust Monitoring Platform
Are Enphase Micro Inverters Worth It If They Clip?
Enphase Micro Inverters create a highly reliable solar system. There is no single point of failure, like there is with a string inverter. However, using a microinverter with a high power solar panel can cause clipping, but there are ways to avoid this.
Are High Power Solar Panels Worth The Extra Money?
Not if they clip! If you want 400 watt modules, you will get more production with an inverter that doesn’t clip, like a SolarEdge string inverter. If you want the reliability of microinverters, then get lower watt modules. Don’t be disappointed if you buy more expensive, higher output panels and not get the full potential out of them.
When paired with the right model of inverter, premium panels are worth it because they produce more power. Combined with Enphase micro inverters, they’re more reliable. It’s important to understand the limits associated with each.
The Best Enphase Micro Inverter For High Power Solar Panels
The right combination of solar equipment can achieve high production and yield the best return on investment over time. There are two factors that determine what Enphase micro inverter pairs best with high-powered solar panels: Maximum Output Power and Module Compatibility.
MicroInverter Maximum Output Power
Wattage Of High Powered Solar Modules
Solar modules are now available in the 400-watt range. Sunpower has a series of panels over 400 watts. LG, REC, and Solaria have panels that are 360 watts and above. If you’re considering a panel in this high power range, carefully consider the inverter capacity.
Don’t Exceed 400 Watt Solar Panels With Microinverters
The highest capacity output microinverter that Enphase makes is the IQ7A series. This microinverter is also the SunPower branded SPWR-A4. The continuous output power is 349 VA, and the maximum is 366 VA. (VA ratings should be compared to AC rating, about 10% less than the DC rating of the solar panel) Read more about the SunPower SPWR-A4 in our SunPower review.
To avoid clipping, stay at or below 400-watt solar panels when using the IQ7A. Enphase currently doesn’t have an inverter with a higher capacity, so don’t waste money on 440-watt panels unless you choose a SolarEdge inverter.
The Best Inverter For High Power Panasonic Solar Panels
Panasonic has 96-cell architecture in their solar panels, so they only can pair with Enphase IQ7X models which is made for 96-cell panels. This model has continuous output power of 315 watts, and a max of 320. It pairs perfectly with Panasonic 325 – 340 watt solar panels. Clipping is non-existent. Panasonic has a robust warranty for 330 watt AC module systems, the AllGuard Warranty. An AC module is a solar panel with a factory mounted micro inverter.
The Best Inverter For High Power Sunpower Solar Panels
Sunpower has 360 and 370 watt 96-cell panels that pair with a twin of the IQ7X model (Enphase IQ 7XS), but clipping and power loss can occur with this combo. Sunpower’s 400 – 420 watt panels are paired with their branded version of the IQ7A (SPWR-A4). The continuous output power is 349 VA, and maximum is 366 VA. Don’t go over 400 watts per panel unless the panels are cheaper, which occasionally happens with Sunpower special promos.
The Best Inverter For High Power LG, REC, & Solaria Solar Panels
For 340 – 350 watt solar panels, the IQ7PLUS is fine. It outputs 280 VA continuous, so the panels may clip if they’re pointing south and it’s a sunny, clear day. Since it’s the AC rating of the panel that matters (10% loss), a 340 watt panel is approximately 305 watts AC, so any clipping would be minimal. Any panel with 340 or lower wattage panel is an excellent choice for the IQ7PLUS.
For panels 360 watts or higher, opt for the IQ7A, with 349 VA continuous and a max of 366. As I said before, no need to go above 400 watts unless you get a bargain.
Is Overclocking Good?
Many installers believe that losses due to clipping from overclocking inverters are offset by morning and afternoon gains. The chart below shows the theory of how peak clipping losses (red) from an under-sized inverter can be offset by morning and afternoon gains (green). Many installers overclock string inverters because they believe it will produce more power. But doing that limits your ability to expand the solar in the future. Tell your installer you want to oversize your inverter so you can add panels in the future if needed.
In SoCal, I wouldn’t recommend more than a 1.2 DC to AC ratio, but some installers push it to a 1.3 – 1.5 overclocking ratio with both string and micro inverters.
They try their best to rationalize why 280W output from a 400W panel is acceptable. Enphase has a Tech Brief posted to their website to address this common concern: Why Is My PV Module Rating Larger Than My Inverter Rating?
Is Clipping Ever Good?
Many people think that micro inverter manufactures push the idea that clipping is good because they do not have a product that doesn’t clip. If you want the most power, you won’t care about keeping an inverter maxed out in the early morning or late afternoon. It’s been said that Time Of Use peak afternoon rates can counterbalance the losses, but that’s difficult to calculate. However, there are 2 legitimate reasons for lower capacity inverters:
1) Electrical Panel limitations. When choosing between an inverter that will clip and one that will not: your installation may be cheaper with a lower capacity inverter since you won’t need to upgrade your electric panel or add a meter adaptor.
2) Inverter pricing. Enphase IQ7A microinverters are usually more expensive than the other models, about $20 – $50 per micro. Same is true with string inverters: their prices jump for increased capacity or multiple inverters.
Are There Disadvantages to Using Microinverters?
- Enphase Microinverters are usually more expensive
- Micro-inverters have a lower capacity than string inverters
- Micro Inverters have lower efficiency than string inverters: 99% vs 97%
- Clipping can occur with high power solar panels if they aren’t paired properly
- They can be less compatible with Battery Back-up Systems than SolarEdge
- The Envoy Monitoring Unit only has a 5-year warranty
The Best Inverter For High Powered Solar Panels
In conclusion, Enphase is still the best choice overall. With string inverter systems, when the inverter fails, the whole system goes out. With micro inverters, each panel operates independently — so no matter what happens to any one panel, the rest of your system keeps producing. That being said, sizing the solar panel’s production to the microinverter capacity is the most important step when designing your system.
What Are The Best Grid Tie Inverter & Solar Panel Combos?
- Enphase Microinverter IQ7A with LG 375 – 380 watt solar panels
- Enphase Microinverter IQ7X with Panasonic 330 or 340 watt solar panels
- Sunpower SPWR-A4 with Sunpower 440 watt solar panels
Learn more about solar power for your home with our insider’s guides to going solar. If you’re wondering if using an online quoting platform is a good idea, read our EnergySage review before you sign up for online solar quotes.