The array
We don’t actually own our solar array, it was installed by the previous owner of the property through a 25 year ‘rent-a-roof’ scheme in 2010. From what I’ve been able to determine the array consists of 15x 240W panels on a single string, totalling 3.6kWp (kilowatt peak). This is running a GoodWe GW3600S inverter.
Our roof is more or less due South facing with a pitch angle of around 38 degrees.
Gathering the data
Until getting our Zappi 2 EV charger installed, the only monitoring we had for the solar array was through the online portal for the GoodWe inverter, which was unreliable to say the least. Most months it would loose connection for at least 10 days, if not more. So prior to February 2024, a lot of the data I’ve gathered is approximations, based averaging out the data that was recovered across the whole month, or in some cases I was able to compare SolCast data against our measurments and figure out a correction factor for days when the inverter didn’t record. Again this wasn’t ideal, but better than just averaging.
Since having the Zappi installed with the extra Solar monitoring CT clamp, I’m able to reasonable accurately record solar generation more reliably. Comparing it against the inverter data when available, it tends to be accurate to within ~100Wh.
2024 is by far the most accurate year of data collection so far, but I think the previous years are reasonably accurate by comparison; certainly not wildly out once you take in to account varience in weather year-on-year.