diy solar

diy solar

Parallel EW panel to enphase microinverters

kiddor3

New Member
Joined
Apr 30, 2021
Messages
4
Given how cheap Solar panels are, and how convenient enphase micro inverters are, I have been trying to figure out if I can half the microinverters, by connecting one microinverter to a panel facing east parallel with a panel facing west to maximize the output. Has anyone done this or has advice on how to verify if it's possible?
E.g. What is I connect 2 Qcells G6+, once facing east and another west, with one enphase IQ7+?
 
Last edited:
Yes, or at least that's the thought. With panels coming about the price or cheaper than the micros, if I could get multiple panels one facing east and one west, I should theoretically be able to use the micro more efficiently and save on half the cost.
 
I remember a while ago I watched a video of a dual panel micro inverter but the person was having issues with the micro inverters, but they had double in/out connection ports for the 2 panels to connect to. Not sure if something like that would be simpler to put together. I would think that since the Enphase inverters only have one in/out ports you would have to rig the cables somehow and splice, the 2 panels into one in/out port. Not sure if they still sell the M215 micro inverters but at one time they were going for a very good price, so it would be economically feasible to go that route. Will bought some panels for 50 bucks each not long ago, all you have to do is add the M215s to each and create as many legs as needed. I have 2 legs on mine with IQ7+ and 315 watts panels fix roof mounted, average daily production is approx. 33-35 kW, one leg with 12 panels and the other one with 6 panels facing the same direction. I'm pretty sure a system with M215s and cheap panels could achieve even better production.
 
That's sweet. I love in pacific Northwest... Not much sun to generate that much here on my rooftop. There are some multi MPPT micros or there (eg APSystems, WMV, etc), but given an enphase works to 15A/60V input. If I can get panels with 50V/10A range facing EW parallel, I should theoretically be able to utilize 1 micro right? I was thinking of just using a parallel Y-connector.

Is there a benefit to m215? Or is that for the cost? With new panels, it doesn't make sense to get lower max outputs.
 
The idea is good, but with inverters being 200 to 300W, and panels 300W to 500W, two panels don't add up to the right wattage. Excessive clipping. It could be done with smaller panels. Two, 200 to 250W panels at 90 degree angle to each other would be a good fit for 300W inverter.

I do this with string inverters. Back when I had 2500W inverters the voltage/current limits from panels didn't add up well, but with 5kW to 10kW inverters I'm able to parallel 2 or more strings of panels.

Multiple angles of panels in parallel means they aren't at quite the optimum MPPT point, but only about 2% off.
 
I see. That's interesting indeed. I was thinking of putting them one each on east and west facing roofs. They are about 38 degrees (not 90). However I do live in the pacific northwest and here I am already losing power due to South, so my panels are not really grenadine to their film efficiency most of the time. What does 2% translate in practice? I feel doubling the inverters isn't going to get me much more, so the extra inverters feel waste.
 
SMA and other string inverter manufacturers used to say all strings in parallel had to be same orientation.
Later they tried multiple orientations and reported power produced was 2% less than if the two strings each had its own MPPT.
So that should be in practice. You waste 2% of PV panel capability, but get more out of the inverter due to higher PV wattage throughout the day.

With 90 degrees, trig or Pythagorean theorem, says diagonal of triangle is 0.71 times sum of two sides. Closer to same orientation, area presented to sun is closer to sum of the two panels. Not taken into consideration is that off-angle more of the light is reflected not absorbed. So it is a first-order calculation.

Figure out presented area for 38 degrees and you'll see how much over-paneled it would be.

These days, Enphase is advertising its inverters based on how big a PV panel you could connect. When available wattage exceeds inverter's output rating, power is clipped. Some amount of over-paneling is useful. If you already have a 300W STC panel (maybe 270W PTC?) on a 215W inverter, in that case I'd suggest more inverters for more panels. Unless panels have no tilt to the South and sun doesn't get that far North, so presented angle already reduces output so no clipping.

I prefer string inverters - more series/parallel configurations to fully load it. But now that RSD per panel is required, not so much savings.
 
Back
Top