A Modest But Well-Assembled Home Hydropower Setup


Pelton Wheel
Pelton Wheel




It’s good to see such a well-assembled small hydro setup. The last one we featured was a little more basic, being made entirely from trash, but before that we showed you one made from a former washing machine.

21 thoughts on “A Modest But Well-Assembled Home Hydropower Setup

  1. Pelton wheels are interesting in the fact that they operate “ballistically”. Each scoop gets a squirt of water that is essentially freefalling, so you can think of the whole thing like stopping a flying table tennis ball with the racket – you’re moving it along with the ball trying to speed it just right so the ball neither bounces nor continues forwards but drops dead down. That’s when you’ve extracted all the kinetic energy and the wheel is operating at maximum efficiency.

      1. The scoops are specifically designed so they turn the flying slug of water back towards the jet, and the act of smoothly turning it around causes a centripetal force that pushes on the scoop and consumes the kinetic energy into the motion of the wheel.

        It would work with just flat plates like the ping-pong racket example, but the impact would be very brief and most of the kinetic energy in the slug of water would be carried off with the resulting backsplash.

        1. Whoops, should mention that’s absolute pressure shown above, where 1 bar is normal atmosphere, so 1 bar at surface, when he says 55psi, that’s relative to atmosphere, so looks like a bar and change less than that chart.

      1. ” or at the bottom of a really tall 4″ pipe.”

        Static pressure. Flow pressure is different due to the resistance of the pipe.

        Trick question: what is the pressure at the open end of a 4″ pipe connected to the bottom of a 38 meter tall reservoir full of water?

    1. I didn’t read his setup, but when my sister-in-law lived on the West coast of Vancouver Island, they had a year round stream coming down from the mountain behind them into the ocean bay in front of them. 300′ up the mountain a small dam was built, and a ~6-8″ pipe in the dam fed the water into the generating house near the shore. That 300′ head gave them 10kW of power 24 hours a day. (There was also a 1″ tap that fed water to all the houses in the community – fresh ice cold mountain stream water on tap! – no pressure pump needed!)

      It was a fascinating system. Rather than vary the water input and therefore electrical output, the wheel needed a 10kW load all the time (+/- some factor – maybe as much as 20%?), or bad things would happen. There were essentially 3 circuits – general use, hot water tanks in community kitchen and 10kW of baseboard heaters in my sister-in-law’s house.

      The general use circuit always had power. It fed lights, outlets, etc.
      If there wasn’t enough real demand, then the hot water tanks were fed. Once they were hot and their thermostats cut out, the rest was dumped into the baseboards in the house.

      Fortunately my sister-in-law is notoriously cold blooded :-) as the house would often be 25C inside, with windows open (and while we were there, it was 0-10C outside).

      Only real problem with the system was all the clocks on the stoves, microwaves, etc were always wrong as the frequency of the system varied wildly as the load would change.

      1. It was likely an induction generator, where both the voltage and the frequency depend on the running speed, and they made it maintenance-free by leaving out all valves and mechanical feedback, so the only way to keep the voltage in control is by applying a more or less constant load.

      2. How many clocks are still line frequency dependent these days?
        The fresh mountain spring water on tap is nice. Luckily this is the case in Vienna (capital of Austria). They even installed a turbine in line of of one of the main water pipes to reduce the pressure. So our drinking water/tap water generates power before we get it into the apartments.

  2. Take a measure of how much you consume in a period of time (24h or longer) and see how many amps average it is.

    With a decent sized battery bank (or a grid tie system) and some conservation you wouldn’t need to many amps I guess.

      1. The key phrase here is “consume in a period of time”. You want watt-hours (or amp-hours if you factor in the system voltage). Take a look at your electricity bill – it *should* tell you your average daily consumption. My off-grid system has a battery bank providing a nominal 24VDC (plus a sine-wave inverter for 240VAC), and the 12VDC PV panels are wired series-parallel to provide a suitable feed.

        If you want to go off-grid, the first thing you need to do is an energy audit. Fire up a spreadsheet with *every* device’s description – from phone chargers to pumps, lights, computers, stereo, washing machine, etc) – its rated power level, and the amount of time its on every day. You can do some creative work with formulas to average out things you don’t use every day. That gives you daily average consumption. You’ll want batteries suitable to give you 2-5 days independence, i.e. 2-5 days of cloudy weather before you crank up the generator, then enough PV to recharge your daily consumption, based on x hours per day at peak PV output in sunny weather during spring and autumn (generally 4 -5 hours per day), multiply by 1.1 to mitigate battery inefficiency (you have to put back 110% of what you take out), then 1.1 again to mitigate inverter efficiency, and you’ll have a good starting point for the overall “size” of the system you’ll need – plus a backup generator, of course.

        1. Oooor… you could just look at your power meter and take the number down every day to get actual measurements. Otherwise you end up spreadsheeting your stereo’s “PMPO” wattage and other completely imaginary numbers that are thrown in at best guess or worst case estimate and you end up none the wiser.

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