Hydro Update

The first Hydro proposal suggested that we take as much as possible from the stream, and so generate the maximum amount of power.

But this meant that we’d have a large intake, a large pipe, a large turbine, and a large cable to connect the turbine to the grid. And they would all get used to their maximum for only a few weeks each year.

So TGV Hydro came back with plan B:

Plan A Plan B
Peak flow 35 l/sec 14 l/sec
Peak power 13.7 kW 7.2 kW
Average power over a year 5.8 kW 4 kW
Total cost £115k* £62k
Payback time 9 years 7 years

*Plan A needed lots more electrical infrastructure before it could be fed into the grid. Which we ended up buying anyway, as the combination of PV and Hydro needed a bigger transformer.

They key number here is the payback time, which is a proxy for return-on-investment – they key measurement for the viability of the scheme.

So, we decided on the smaller scheme, with the higher ROI.

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