Panels sizing wattage for Enphase IQ7+

Is this a good offer:
6.6kW - *20 x Trina ‘PERC Split Cell’ 330 watt panels +20 x Enphase IQ7+ Micro Inverters - **$8,290
** (Includes GST and is after Government Rebate - STC’s)

It’s not a bad price for top quality inverter, and decent panels. Does the solar company get good reviews?

TRUSTPILOT SITE gives them a 4.8 338reviews

I don’t really know anything about Sydney prices but I know Trina are good value panels and Enphase are good inverters. It might be worth considering SolarEdge optimised inverters, which as far as I know work in a similar way to Enphase but are probably cheaper. They also don’t have the problem of needing to get up on the roof is there is a problem with an inverter and come with a 12 P&L warranty on the inverters and 25 P&L on the optimisers.

Hi JediKnight

I install only Enphase products and would say it will be an OK system for you. The panels are the issue. At 330 watts they are underpowered for the IQ7+ inverters. The sweet spot for the IQ7+ is between 360 and 380 watts. We are currently installing 405 watt panels with great results. You will get a massive power harvest with the 330 panels but could benefit even more with panels between 360 and 380 watts.

The 1/2 cell panels we have been using are excellent (JA Solar - 405). We were worried about the panels being too oversized, however the power harvest from these, with the IQ7+, has been unbelievable. Back to your 330 panels. We compare our systems for panel output and with Enphase we can do so for any day of the year. I just ran a comparison between 340 watt panels and 375 watt panels. Same area and same conditions (both using Enphase IQ7+ micro’s) The 375 watt panels are consistently out performing the 340 watt panels by 25%. That is the advantage of oversizing.

Here is the issue - while the panels are rated for 330 watts they almost never reach that output, or come even close, most of the time. I would check the NOCT rating for the panels. In my view, that is a far more accurate rating for real world conditions and power out put from the panels. The way the Enphase micro’s work best is with oversized panels so that they can be flooded with power to their max for as long as possible. In the case of the 330’s you will normally see a max production of about 10% (or more) less than the panel rating. This puts the max output from the panels at 297 watts and the IQ7+ actually max’s at 296. This would mean that for a very short period of the day the micro’s would be performing at max output. Plus, figure in less than perfect panel angle, clouds, shading, dirt etc. and that panel rating starts to rapidly drop off. So by increasing the size of the panel you ensure the micro’s perform at their peak for as long as possible each day.

Don’t get me wrong - stack your 330 watt Enphase system up against any string inverter system - including Solar edge (with their optimizer system) and your power harvest will be greater (In many cases MUCH greater). It is just that it could be even more.


Basic difference between the IQ7 and the 7+ - IQ7 max power through put 250 watts. IQ7+ max power through put 295 watts. Next difference - IQ7 is for 60 cell panels only and IQ7+ is for 60 or 72 cell panels. Now as to rule of thumb for panel sizing or oversizing. Bigger is better to a point. 300 and 310 - watt panels are best suited for the IQ7 since it has a maximum power out put of 250 watts; however you are going to need a substantial number of additional panels to make up the power difference of the IQ7+ that will out put at a maximum 295 - watts and when correctly matched with 360 - watt or higher panels produce huge power gains. Our field tests have shown as much as a 25% increase in power out put when increasing the panel size from 330 - watts to 375 - watts. So for the best bang for your buck look to the IQ7+ and match with a good quality LOW LIGHT panel around the 360 through 410 - watt range. As well, our latest field tests on the 1/2 cell panels are producing excellent results with maximum power gains of about 7 - 10% above what our 385 - watt panels are producing. That is about a 5% increase in panel wattage for up to a 10% gain in power out put.

Hope this helps.

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This what i have been looking for, real life content.

How do the IQ7X stack up?

Hi @BrownBird

IQ7X is the same generation inverter as the other IQ7s, it’s just for a larger wattage panel.


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