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Author Topic: Hydro / Combined system - Am I on the right track?  (Read 3417 times)
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« on: February 03, 2019, 03:21:39 PM »

Hi Folks,

First post so be gentle with me  Smiley

My question is, given the Hydro / PV / Wind / Wood-burning options open to me - Am I on the correct track in in prioritising Hydro as my main energy source? - I think so, but would very much appreciate comments from you folks who have been there and done it.


 18 months ago we purchased a derelict water mill here on the Isle of Man, basically 4 walls and part of a roof, 2.5 acres of disused (silted up) mill ponds surrounded by lots of trees many of which need to come down.
 I've been very busy on the build and therefore energy system design has only been at the back of my mind - but we are now rebuilt, windows, roof and extension on - total about 550M2.

Lots of insulation ranging from about 75mm Kingspan in the existing mill up to 150mm Kingspan in the extension. About 200M2 of flattish (low angle) south facing roofing available for solar.

My thinking;
1. Insulate (Done)
2. Under floor heating on top of rigid insulation, 40mm Gyvlon screed, 20mm porcelain tiles throughout - all to be laid this month.
3. Water has about 10 meter head from back of furthest mill pond to where the mill wheel was - water flow 365 days per year but ranges low in summer (obviously) to just about 100% filling the 1meter Dia Culvert through the dam in winter. Stays pretty clear of debris.
4. Thinking Ground source (i.e. water source) heat pump in ground floor of mill piped through 600mm stone walls direct into stream (there is a big 'trough where the wheel used to be).
5. Thinking low head turbine with direct connect DC alternator to battery bank / inverter system basically driving background pumps etc. with water heating elements for either DHW or UFH top - up.
6. Electric here on the Island is +/- 16p per unit but drops to 7p / unit IF your main heating source is electric (i.e. Heat pump) (8 hours at night plus 2 hours per day).
7. Mains electric (off peak) as emergency Hot water back up.
8. Log burner with felled trees as heating back-up.
9. Possibly add Solar P.V. when time permits.

What think you learned Gentlemen?



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« Reply #1 on: February 03, 2019, 04:00:43 PM »

Hi there Drumbeat and welcome.  Sounds like you should be able to put a nice system together with Hydro and PV.

For the best advice on Hydro, apart from the resident experts here, I suggest you get in touch with Hugh at Apart from being the "wind guru" he has been doing hydro for years.  He is very free with time and advice. Suggest you ask him specific questions and give him detailed info.  There is a tab on his web page marked Powerspout Hydro, take a look see.

We like to see RE porn so pictures please.

Best wishes.



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G69, Glasgow

« Reply #2 on: February 03, 2019, 04:56:05 PM »

hello and welcome,

First and most important. For turbines, not waterwheels, you determine the usable head which is probably from the surface of the mill pond you extract the water from (whichever one you use) to the point where the water impacts the turbine. If you plan a traditional waterwheel it is for an overshot wheel the wheel diameter and for an undershot wheel the height from the point where it enters the wheel to the bottom of the wheel. (Sorry if this is obvious)

Next you need a reasonable estimate of flow (in litres per sec),
to just about 100% filling the 1meter Dia Culvert through the dam in winter
sounds like you have got lots!  Grin

Power output (in Watts) will be flow in litres per sec (actually mass in kg per sec)* 9.8(gravitational acceleration) * head in metres. Allowing for system efficiencies actual output will be about 50% of this for turbines/overshot wheel and perhaps 20% for undershot wheel.

e.g. With a 5metre head and 100 litres per sec you would have a theoretical 5*9.8*100 or 4900Watts or probably about 2.5kW in practice.

In summer 4-6kW of PV (24-36m2) would be sufficient, depending on  how far you want to take it a small battery bank could see you approach an off grid status, with the hydro providing a backup function

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« Reply #3 on: February 03, 2019, 11:03:10 PM »

but we are now rebuilt, windows, roof and extension on - total about 550M2.

Hi Steve

 What number of kWh electricity and heat do you expect per year ?

beside that, i first would concentrate on what  the water  can deliver    in relation to power ( that can be transformed to heat as well) , if its not enough in summer , than surely  PV is the partner !

If the watersupply /flow is sufficient  for the needs , the  installation or the system design  is a no brainier   (depending on local regulations )  and



1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
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« Reply #4 on: February 04, 2019, 07:25:42 AM »

10m head is not a lot if the flow is poor in summer -does the flow drop away after the old wheel position and could you place the turbine further down stream to take advantage of additional head and bring power back.

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« Reply #5 on: February 04, 2019, 09:42:05 AM »

There is a turbine Cragside in Northumberland which operates on very little flow and head but gives a very good output. A similar design would not be cheap but if you have the mill pond it would work

Also another mill that's been on the telly, is Gayle Mill at Hawes in Wensleydale.
Its only 35miles from me and I have seen it operating as a saw mill the output is amazing.
When it was first renovated it was on a BBC program with Griffith Rhys Jones.
The second was channel 4 with Guy Martin
I cant remember which program gave a very detailed explanation of how the turbine worked, but the water outlet was as important as the input.

16 X 240W Panasonic panels with a 3.6 ABB ( PowerOne ) inverter
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« Reply #6 on: February 04, 2019, 12:23:52 PM »

There is a turbine Cragside in Northumberland which operates on very little flow and head but gives a very good output. A similar design would not be cheap but if you have the mill pond it would work

That's a lot of turbine for a rated power of 12 kW. Good as a long term investment though.

When youíre thirsty, itís too late to dig a well. - Unknown
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Forest of Dean -Gloucestershire

« Reply #7 on: February 04, 2019, 08:12:48 PM »

Don't look for 12 kw -be happy with 500w or 50w . 
Even 50w x 24 hrs is 1.2 units daily.
I second the earlier poster -go to the powerspout website and  play with the  figures .
Measure  your flow - how  long to fill a 25 litre bucket - convert to litres /minute .
And yes we need pictures .................
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« Reply #8 on: February 04, 2019, 10:42:43 PM »

Difficult to say if you're on the right track until you have some hard figures for your hydro-resource - filling a 1m dia culvert sounds impressive, but if it only does that during a winter storm it isn't much use (my own stream would have filled a 1m culvert during storm callum last october, but 3 hrs after the rain stopped it was back to its usual level - much more useful is the fact that it still provides a useable amount of water 2 months after the rain has stopped).

you really need to get some accurate figures for what it does a few days after the rain has stopped, a week, 2 weeks, a month, etc; these figures will tell you what size turbine/generator/penstock you should be getting.

the fact that you have the leat pond(s) is an advantage - if you can partially use the top pond without sacrificing too much of your 10m head then you can capture some of those winter storm waters and make good use of them - something I can't do with my system alas.
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« Reply #9 on: February 05, 2019, 07:29:09 AM »

Good Morning All,

We have a very small burn runs down one edge of our property and I idly wondered a while back after we moved in whether it was in the least bit viable.

I did actually dam the burn and inserted a sheet of plywood with a measured slot and used to take readings. I guess there are more sophisticated ways but it did give me some baseline figures.

The whole idea might be viable for a small turbine in my case but I'd need to buy the piece of land the opposite side of the burn to the bit we currently own first.



1.28kW on a Lorentz ETATRACK1000 + 1.44kW/ SB3000TL-21 (FIT), 1.28kW/ SB1700 (ROO/FIT). CTC GSi12 heat pump/Ecosol/Flowbox 8010e/Gledhill ASL0085 EHS/3off Navitron 4720AL Solar ET & Immersun T1060/T1070/T1090. 3.375kW/ SMA SB3600TL-21 and a Sunny Island 4.4M-12 c/w 15.2kWh battery and a Renault Zoe.
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« Reply #10 on: February 05, 2019, 08:43:04 AM »

I think if I were in your shoes I would have prioritised solar PV while I was doing the roof and had the scaffolding up. I'd look at roof integrated solar to save on roof tiles and to take some weight off the roof, especially if you have stone slates.

5.18 kWp PV systems (3.68 E/W & 1.5 E).
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