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Thank you so much! You've really taken pains to explain things in a way that I can understand. I have a better framework now for thinking about this. Thanks again.

But that's in the wrong direction. The car is reporting receiving more energy than the three meters say is being pulled out of the outlet.

I'm considering a grid-tied system that would also be off grid during our frequent power failures. I would anticipate putting a row of panels in portrait mode just below the peak of my roof (that faces 187°) and another row below them across the upper part of the front-porch roof - about 30...

I don't yet have solar but my issue is of concern to anyone interested in measuring electric-energy use. I'm charging my PHEV from a 120V wall socket using the car-manufacturer's charger. I started monitoring the energy required with a Poniie PN2500 meter, and I've since supplemented that with...

I sounds from the Solar Ray video that with string inverters there's not even a need for optimizers. My shading situation seems quite different from the shading in his testing though. And it's extremely different from what was tested in the NRG video, in which only a tiny fraction of the total...

Thanks for these comments, which seem to support those of chrisski and Ceberha above, which I also very much appreciate. I'd like more output during the winter months but I can live with this kind of output reduction. Regarding other roof faces - The house is L-shaped and there is a shorter...

Thanks for that very clear discussion.

The PN2000 and PN2500 meters claim Class 1 accuracy, which is "1% at full rated current", which is 15 and 25 amps respectively for the meters. (I charge at 9A.) The P4400's accuracy spec is "+/- 0.2%". The PN2000 and P4400 display KWh to two decimal places, the PN2500 to three. My charging...

I'm planning to mount 16 panels in portrait orientation in a long single row under the ridge of my roof. In the morning because of trees to the east, the panels will be exposed to sun progressively from west to east. In the afternoon trees to the west will shade the panels one-by-one from west...

Yes, I didn't mention those other details because I've assumed those aspects would be under control and only wanted to ask about the wiring-configuration issue. I'd probably be going to a Sol-Ark 12K, which has an MPPT range of 150-425V. They'd be 400W+ panels, probably 66 or 72 cells unless...

The bypass panels are my hope too. See my reply just above. I don't exactly understand what you meant in your last sentence. Would you mind expanding on that a little?

I guess this is a reply to several of your posts, fafrd. I'm finally getting back to deciding what to do. Although I posted on this DIY forum there are too many things I don't have a good grasp of, and in the end I will be working with an installer. But I still want to try to understand the best...

Secret panels. Good one! I don't have any panels in my possession or on order. I'm just thinking about plans and wanted to explore this configuration issue. Apparently my original post wasn't very clear. I'll have 16 panels and two MPPT's and will connect eight panels to each MPPT. The question...

I agree. It's too bad that neither my nor BMW's measurements can confirm that 2.3. I'm guessing that BMW is reporting miles/kWh based on the amount of energy the electric motor is consuming. Unfortunately the amount of energy the driver has to put back into the car includes the amount required...

Now I've had the opportunity to look at this. Over a full charge cycle the power factor hovered at about 98.9% - far too high to explain the meters reading 10-15% lower than what the car reports. Incidentally, the discrepancy between the meters and the car is pretty linear with all-electric...

I'm struggling with what happens when shading starts with a 4S2P array. When two of the four panels in one parallel substring become shaded and the bypass diodes have kicked in the voltage produced by that side of the parallel layout will be halved. The other four-panel substring in the parallel...

Yes, those numbers make sense - they're both *lower* than what your lottawatt says the garage board is delivering. My problem is the opposite - the car is consistently reporting *higher* numbers than what my three meters say is coming out of the wall.

Thanks for your reply. Unfortunately, I didn't note the PF in any of my charging sessions. I'll be charging it again on 8/7 and will check this out.

Sorry, wattmatters. I missed that you were the one who had made that comment. The car is a BMW X5 50e. I think your suggestion that the car isn't accurately reporting the kWh required to recharge the battery is correct. Unless there's some systematic error in these three $30-60 plug-in meters...

Thanks for these responses. I take the points that MisterSandals and time2roll have made about using 4S2P arrays. As I understand it, in that configuration one shaded panel in a four-panel substring would essentially kill the output from that substring and the array output would be cut in half...