Have been quoted Qcell Peak duo G7.2 400w panels with Enphase IQ7+ Micro Inverters.
I am concerned that the inverter has an input power of 295w on 400w panels, is this an issue due to clipping?
The clipping can be an issue with the 400-watt panels, however it is a very minor issue even in direct unshaded panel placements with perfect sun orientation. We are currently using JA Solar 405 split cell panels with the IQ7+. In most installs your panels will never hit their maximum output (wrong orientation, shading etc.). Our installs have perfect sun conditions and we can achieve perfect orientation (flat roof installs with 0 shading and adjustable racking systems) and most of the time we are still not able to produce above the 295 watt limit on the IQ7+.
In fact, we just did system reviews on the 405-watt installs, and found that on the best days, with clear sunny skies and correct orientation, the panels were only able to surpass the 295 barrier for at most two hours. This was more than compensated by the side load power gains from increased production in both the mornings and afternoons.
I am presuming your install will be a normal rooftop install on a pitched roof. In that case you have no concerns, as the panels will not normally break the 295 barrier and even if they did, it would be for a very short period.
Have a look at the NOCT rating for the panels. This, in my view, is a better determining factor for the normal power levels you can expect from the panels - for example the JA Solar split cell 400-watt panel is rated at 302-watts under the NOCT rating.
The time when the IQ7+ really shines (pun intended) is when matched with a great low light panel. With this combination, you get excellent low light operation (mornings and afternoons, cloudy days and shaded areas). This low light operation allows the panels to flood the IQ to maximum earlier in the day and later into the afternoon (side loading), increasing the overall output of the system substantially.
Hope this helps.
As a follow up: we have been very excited and pleased with the results of our latest installs using the JA Solar 405-watt panels and the IQ7+ micro’s. We have seen daily power production of over 2.58 kilowatts per panel. Our solar day is rated at 4.5 hours, Which would normally mean an average of 1,822.5 watts harvested per panel per day. This means our systems are peaking at more than 42% above the area rating. We will need more days to see what the overall daily average is but, from our experience with smaller panels, it will still be way above the area rating.
Hi there, how long have you been installing the big panels with the IQ7+? no problems at all?
The big 405’s are new for us here in Mexico. We have two systems with them in operation currently and are in the process of three additional systems currently. I was not prepared to install the JA Solar 405 1/2 units until Enphase assured me that there would be no issues with them and so far they have performed beyond my expectations.
They are rated as a low light panel which gives them a great early morning and late afternoon kick. We have long days of full sun, so we are able to do some great comparisons for production. They are slightly better than our 385 panels and substantially better than the 330 - 365. If you have the choice, I would go with a good quality low light panel in the 375 - 385 range for your best cost to production ratio. If your choice is between a smaller panel (below 375-watts) and the 400+ panels I would go with the bigger panel. The extra cost for the extra power produced is well worth it.
This discussion has been super helpful for me, so thought I’d add what I’ve found from Enphase.
I’ve been looking to get a SunPower Max 3 400W/Enphase system installed in Melbourne, Australia, and had conflicting information from installers. One was happy to do the install with an Enphase IQ7X, the other said the best they could do was a 360W SunPower.
Long story short, one of the installers got me in touch with Enphase directly, and they’ve confirmed that for the Australian market, the 400W/IQ7X (not the 7+) is a supported combination, and they will provide warranty. Basically the conditions required for IQ7X to be incompatible (temperature below 3 degrees C and full power generation from the panels) would never happen in any Australian capital city. While there may be edge cases in some of the mountainous regions, it’s considered highly unlikely.
In short, SunPower Max 3 400W/Enphase IQ7X are fully compatible and have warranty in the Australian market with only 2 caveats:
- installed below 1000m altitude (most of Australia)
- not installed on a dynamic PV tracking system
Nice one @SolarSam, thanks for your input.
Very useful content guys. So how do I determine the most compatible PV module for IQ7’s? Live in high country (relatively speaking), more dry cold than wet - Near ACT.
Is there a formula to calculate best fit module with Enphase?
It would be nice if there was a formula. Unfortunately, with the many different panels available, it is impossible to come up with a standard determination based solely on size of panel. What we look for are the following parameters:
- Oversize the panels so that the bell curve is greater than the throughput of the micro-inverter
- Check the “real world” rating for the panel - this is usually 70 to 100 watts less that the panel is listed as - and make sure that this “real world” rating is at or just slightly above what your micro-inverter will max out at.
- Make sure that the panels are designed to maximize production in low light conditions.
- Make sure the panels are designed to produce as much power as possible when they first go into operation each day - such as the technology built into the JA Solar 1/2 panels.
If you check all 4 of these conditions, you should have a system that will produce more power and waste as little power as possible. The question becomes which version of the IQ7 is right for you. The IQ7 is designed for 60 cell panels and can only throughput 250 watts, so you will need more panels compared to the IQ7+ or the IQ7A. However the panels are smaller. The IQ7+ will throughput 295 watts and works best with 72 cell panels, excellent choice for most 72 cell panels in the 365 - 390 watt range. Now the game changer (IMHO) is the IQ7A - this unit will throughput up to 366 watts and is compatible with 72 cell panels and we just received word that they work with some 78 cell panels, such as the JA Solar 400 series split cell panel. The forecast on these is up to a 25% increase in power output compared to the IQ7+. These could be a game changer producing up to 75% more power than the IQ7 with only about 25% more space required on a roof per panel. Higher cost per panel and per inverter but substantially reduced costs for other materials and installation due to fewer panels. I know that based on power output our system costs to the client have been reduced by about 50% in the last five years. This is due to the higher output panels and the higher throughput micro-inverters.
There is the Enphase Compatibility Calculator, do you use that?
This is the result for the Trina 370W you mentioned @BrownBird:
This shows it’s compatible with IQ7+, as well as IQ7, but not IQ7X. You would go with IQ7+ as suggested by the installer, and IQ7 would ‘clip’ (ie restrict) the amount of solar your could produce.
While the formula will tell you if the panel will work with the micro-inverter it does not indicate how well it will work. I have used it to determine if the panel will work but fall back on my determinations as to how well it will work for the client. I only use the compatibility calculator when the panel is not listed in my software from Enphase as a designated panel. As you indicated the Trina 370-watt will work with the IQ7+ (and will work with excellent results), however my information is that the IQ7 is not designed for 72 cell panels and the recommendation is to only use them on 60 cell panels. Now, we accidentally installed a 72 cell system with the IQ7 and it worked, but the modules were not covered under warranty because we were exceeding the system parameters (realized the mistake and quickly replaced all IQ7 with IQ7+). Again you also have the different outputs from the micros the IQ7 will deliver max output of only 250-watts while the IQ7+ will peak at 295 watts. The Trina 370 is in the exact sweet spot to maximize power production and minimize power losses when matched with the IQ7+.