Here is a round up of the 2023-24 financial year generation results for our renewable installations.
Hydro
We closed the year with total hydro generation around 124,000kWh. This was higher than last year’s total of 105,000kWh, but still well short of our annual target of 180,000kWh.
We started the financial year with a Spring of relatively high output, following the previous wet winter, running up until mid-June. There were a few brief episodes of generation over the summer, and then we came back on for the Autumn season in September, which was relatively early. However, from November onwards we suffered multiple occurrences of low or no output as a result of very high river flow. As a reminder, when the volumetric flow in the river is very high, the height differential across the turbine drops, causing generation output to drop until there comes appoint where we cannot run at all. The extremely wet autumn and winter has caused this problem to persist longer than in previous years. The chart below, showing generation output, illustrates the stop-start nature of output last winter.
Solar PV
The annual total for the five PV arrays was 173,000, about 12% down on the previous year and well below the average for the previous 7 years of 216,000kWh.
The main reason for this was continued unavailability of the Matthew Arnold Science Block Array. This had been performing poorly since late 2021, and in December 2022 we were advised to switch it off completely owing to issues identified with the panel installation. As the repair required erection of scaffolding, we had to wait until the school summer holidays before we could carry this out. The repairs have now been carried out and the array came back on in August.
We also suffered a period of a few weeks of unavailability of the Aldi array in the autumn. Aldi switched off the array owing to a concern that the array had not self-isolated correctly during a power cut event. It took several weeks for our contractors and Aldi’s contractors to arrange the test which demonstrated that this concern was ill-founded.
Output of the other arrays (TKC1, Matthew Arnold Main Block, Osney Lock) was also down compared to previous years owing to a relatively unsunny summer.