Going Solar: Part 5 – It works

month

Fortunatly for me, the time it took to get all the permits and approvals to install the system gave the utility some extra time to complete their paperwork in the background. This led to the Permission to Operate letter being issued only a couple of days after the final county inspection was completed, rather than the several weeks I had been advised it could take.

With this final bit of adminstrativia having been satisfied, the system went live in late February. Since then, it has been sitting on the roof passively generating electricity whenever the conditions are right. Which, given that it’s located in one of the best areas in the country for solar energy, is most of every day. There are of course some aspects of the installation which make it less than perfect – for example, a very close mountain to the east and south tends to leave the array in shade longer in the morning than would be the case if I was located a few miles further west. Likewise, the pitch and orientation of the roof are good, but not optimal for maximum performance. That said, over the course of several weeks, including some abnormally cloudy days, it turns out that the system is pretty much meeting my usage under the net metering terms.

One of the best features of the system from my perspective is the remote monitoring capability that came with selecting a SolarEdge inverter and the associated power optimizer modules. Instead of having to go to the inverter and click through display menus to get an idea of how the system is working, I can log in to the monitoring portal and see both actual and past performance information at a 15 minute update rate. In addition to overall system performance, the portal also features a map of the panels as they are installed on the roof, which allows easy viewing of how each panel is performing. Although this system does not include a revenue meter from which household consumption can be recorded, the utility provides hourly data based on the installed smartmeter which was part of the netmetering agreement, which provides an hourly net tally.

Samples of this data are presented below, but what is perhaps most important is a comparison of the best and worst production days I’ve had so far. For a given installation, the best production will be long days, cool temperatures, and clear skies. All are important, but clear skies and clean panels are a driving factor. Having run a small experiment, I found that blocking light to about a quarter of a panel at the peak of a sunny afternoon by using a cardboard shield reduced it’s output from around 250 Watts to under 30 Watts. Based on this, I was not surprised to see that on 7. March, a day which started out with heavy clouds and rain I had my worst system performance day even though things generally improved in the afternoon. Likewise, on a cold and clear day following an overnight rain system the power curve was the best observed so far and was a very smooth shape. More typical is the “normal day” which is generally smooth but has occasional bumps of lower performance as clouds pass over.

day_comp

week usage hourlylayout_live layout

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