I’m exploring microinverter options and came across
What’s your experience with this model? Does it provide a noticeable boost in efficiency or performance compared to other microinverters? Also, how does it handle partial shading or lower sunlight conditions?
Would love to hear your thoughts or experiences before making a decision!
“Your mileage may vary” is the usual disclaimer about the fuel-efficiency of an automobile… and it’s also true for domestic-scale PV installations.
It’d cost thousands of dollars to engage someone to make anything more than a rough estimation of the yield of your proposed PV system, and they’d have to know many many details about the panels, their orientation, any nearby trees or hard shadows, and (surprisingly!) even the colour of the paint on a neighbour’s wall can make a significant difference.
tl;dr
I’d say that, when we rely on a professional to design our PV system, we have to trust them to make good decisions on our behalf.
The most careful (and expensive!) consultants would collect a lot of data on our proposed system’s location, and then they’d spend many hours running detailed simulations of some promising-looking designs… then they’d estimate costs and advise us on whether they think the highest-performing system (according to their simulation!) would give us any significant net advantage over the lowest-cost system. In some locations, for some people (especially if they can’t afford a battery energy storage system… but then how could they afford to hire this consultant?), it really matters whether the array is producing any energy in the first hours after sunrise and the last hours before sunset. Other folks will be aiming at getting enough solar energy to keep their electric hot water cylinder hot, even in winter; and they’ll have very few other uses for solar power in their household. Some folks want to have a big enough array to keep their house warm (using heatpumps) in winter. Horses for courses! The efficiency of your inverter (or your microinverters) is a second-order concern, after all, if you have plenty of space on your roof for one more (relatively inexpensive) PV panel rather than spending many hundreds of dollars on a more efficient inverter. The life-expectancy of an inverter is also a significant factor in any “total cost of ownership” calculation – and I think the 25-year warranty on the IQ8 line is a substantial inducement (although I personally would run a due-diligence investigation on any corporation before relying heavily on it staying afloat long enough to honour a long-term warranty!).
So… if someone competent to give such advice has advised you that a 245VA Enphase inverter is appropriate for a PV system at your house, I’m sure you’ll be fine. You’ll never know whether you could have done a bit better (or about as well, but at less expense) with another brand of microinverters; or for that matter with a string inverter (using more than one of its MPPT inputs, if enough of your panels are similarly shaded, or are in a sufficiently-different orientation, that a 2-string or 3-string wiring would give you most of the benefits of the per-panel MPPT optimisation of a string inverter).
I was intrigued by the claims Enphase makes, in their marketing materials, about the low-light efficiency of their IQ8 series – due to their patented Burst Mode technology. However: I see nothing to support these claims on the spec sheet for this series, nor do I see any whitepaper on their website which evaluates the effectiveness of Burst Mode at improving efficiency.
At https://enphase.com/en-gb/download/performance-simulation-between-enphase-microinverters-and-string-inverters-tech-brief, I found an intriguing performance-evaluation. This was a comparison of eight of their 384W IQ8 string inverters with “a popular string inverter solution, whose name remains confidential for legal reasons” with 3000W maximum output power. On an 8-panel PV array (3680Wp) with negligible partial shading, the eight IQ8 microinverters significantly outperformed the brand-X inverter – by roughly 8% on an annual-production basis. They have actual performance for the system using microinverters in Valencia; and they ran a detailed simulation (using PVsyst and a year of meteo data) for this array in four European cities, using both the (simulated) brand-X inverter and the (simulated) microinverters. It’s unclear what advantage the patented Burst Mode technology is providing, as the PVsyst model of an inverter doesn’t include this feature – and I’m definitely “down in the noise” of seasonal and hourly variation when trying to compare actual to simulated performance at the hours of low insolation in Valencia. Possibly the only major difference is that the brand-X inverter has a rather high minimum voltage for its MPPT, and if they had compared with a brand-Y inverter both systems would be producing a small dribble of power during the hour after sunrise and the hour before sunset each day? Then again, maybe Burst Mode does provide a significant advantage in very low-insolation conditions?
I’m intrigued by the possibility that Burst Mode would offer a major advantage over a modern string inverter in the highly-variable cloudiness in my particular location (Auckland NZ). Eventually my 2013-vintage inexpensive string inverter will fail, and I’ll be replacing it with more modern gear. See MPPT is problematic for my domestic rooftop PV in Auckland – cthombor if you really want to read the details of my simulation.
Well I did warn you! tl;dr
