Thread: Solar powered workshop?

Thinking about his slightly differently, I figure that my larger machinery doens't run for long periods of time, eg, you turn on the table saw, use it for 5 minutes, then turn it off, do other stuff for an hour of so, turn on another large machine, use it for 5 minutes, turn it off, etc etc and so the cycle goes. So that peak load from larger machinery which exceeds normal house solar set ups is only required for a short periods of time.

Since I'd need a backup generator anyway, it might be cost effective to spec the solar system for the house and workshop load minus the load of the larger machinery, and buy an up spec'd generator to handle the larger machinery loads. There's switches to automatically start up the generator in those situations, or you just set up a remote or switch for the generator that you flick on before hitting the on switch of the table saw.

I don't think the generator would use much fuel, as it'd only run for short periods of time, maybe 2 hours a day at most assuming I spend an entire day in the workshop. Occasionally it'll be more, like when your dressing a lot of rough sawn timber, but that's not every day. Maybe I spend a couple of hundred dollars a year in diesel. Nothing really.

For the sake of a cost example, it might cost 80k to spec up a solar system that can handle a house, workshop lights etc, plus high draw machinery.

The cost of down spec'ing the solar system to normal house requirements and up spec'ing the backup generator so it handles those short periods of high load when using a larger piece of machinery, might cost 40k.

Anyway, I don't have any numbers to confirm that yet. Just a though

Cheers

Greg

Originally Posted by chocwheaton

For the sake of a cost example, it might cost 80k to spec up a solar system that can handle a house, workshop lights etc, plus high draw machinery.

The cost of down spec'ing the solar system to normal house requirements and up spec'ing the backup generator so it handles those short periods of high load when using a larger piece of machinery, might cost 40k.

Anyway, I don't have any numbers to confirm that yet. Just a though

Cheers

Greg

See what power tools you require can be had in petrol or diesel powered forms. You could run a diesel engine/generator driving (for example) a tablesaw. The electricity would go to recharge house batteries (when required), batteries for cordless tools and mains-powered tools.

If your solar ever fails you, the alternative generation will prove handy, and having to run it to use the workshop will ensure it gets tested regularly.

Prior to the late (I think) 60s, mains wasn't available where I grew up. Dad had a diesel to power the milking plant, and it also ran a generator to recharge the batteries for the house. We also ran the generator on wash day.

The diesel would also be good for pumping water.

you may find what you are looking for here

http://www.caravanandmotorhomebooks....ally_works.htm

Collyn Rivers is the fella's name

he has , I believe , a fully sufficient solar home in Darwin

Originally Posted by ratchet

you may find what you are looking for here

http://www.caravanandmotorhomebooks....ally_works.htm

Collyn Rivers is the fella's name

he has , I believe , a fully sufficient solar home in Darwin

interesting, he has a sample chapter up online which contains this...

"If you plan to use occasional power-hungry equipment (e.g., arc welders, big angle grinders, clothes dryers), but only from time to time, consider scaling the system for ‘normal’ loads and supplying the excess via a generator."

Pretty much in line with what I was thinking.

Cheers

Greg

if you are simply looking into reducing your draw on the grid, perhaps an alternative solution would be to run your own cabling for the power mob (ie get spec's; dig your own trenches etc) and get them to inspect and connect - this will reduce your costs remarkably especially if you have your own gear (Tools and hardware components) or can get them cheap. So connect full 3 ph wiring striaght up - feed off the grid and as a mechanism to reduce consumption wire the house for low volt power for lighting etc but 240 / 3 ph for high draw toolware in the shed and for the high drain housing appliances like the teev, stereo, washer, dryer, PC etc.

Offset all this by wind and solar and feed back into grid that way. expensive but can be done. batteries will always need replacing eventually regardless of type so a sinking fund for eventual replacement is a must.

additionally you can look at hydrogen reformer modules that reform methanol via chemical processes into Ionised hydrogen to power some of your devices - eg low volt lighting.

it very much depends on what your aims are - either green or reduce $$$ - you'll never be free of the grid, free of $$ spend or fully green unless you can work out a way to power nuclear fusion outside of a star. when you work out that please let me know as we can then solve the world energy crisis.

Originally Posted by Ze[U

d;928439][/U]...when you work out that please let me know as we can then solve the world energy crisis.

Will do. Should be ready next week

Hi Chocwheaton,
If you do consider a generator as a backup or to handle the peak loads for your machinery check out a gas fired model. I have seen smaller versions that would be suitable for domestic use, and these are quite efficient.
Cheers Baz

"efficient" is a relative term. internal combustion engines (whatever fuel method you choose) hover about 40% efficiency (I think - I should check but couldnt be bothered).the most efficient machine men make is a bicycle - energy transfer is up near 90% i believe.

Solar for all its benefits just isnt there yet and setup and ongoing costs are substantial. Its like hydrogen cars and other eco fads they simple are not mature technologies and thus not practical.
For most situations a large diesel generator used to run the heavy machinery is the best way to go.
I know of a bloke in NZ who built a turbine & generator over a thermal vent on his property and supplies himself and 2 neighbours with power and himself via a heat exchanger with hot water and under floor heating but we dont all have our own gieser to tap into.
If the property has permanent flowing creek or river you could also look at a turbine that is fixed into the water flow and produced a couple of Kw. There are a few makers of these.
http://www.green-trust.org/hydro.htm
http://www.thesolarguide.com/micro-hydro/turbines.aspx

If you go the solar/wind generation,route, have a look at what is available for the boaties.We have marine solar panels and a marine wind generator, and a 240 volt inverter which provides ample light and small appliances in a two roomed shack, but for tools, microwaves and other heat generating devices, we use a 5 kva inverter generator with auto start.
We have just spent a month in the shack, and the wind generator did not click into gear once, despite some pretty overcast and rainy days.

Originally Posted by chocwheaton

Thinking about his slightly differently, I figure that my larger machinery doens't run for long periods of time, eg, you turn on the table saw, use it for 5 minutes, then turn it off, do other stuff for an hour of so, turn on another large machine, use it for 5 minutes, turn it off, etc etc and so the cycle goes. So that peak load from larger machinery which exceeds normal house solar set ups is only required for a short periods of time.

Since I'd need a backup generator anyway, it might be cost effective to spec the solar system for the house and workshop load minus the load of the larger machinery, and buy an up spec'd generator to handle the larger machinery loads. There's switches to automatically start up the generator in those situations, or you just set up a remote or switch for the generator that you flick on before hitting the on switch of the table saw.

I don't think the generator would use much fuel, as it'd only run for short periods of time, maybe 2 hours a day at most assuming I spend an entire day in the workshop. Occasionally it'll be more, like when your dressing a lot of rough sawn timber, but that's not every day. Maybe I spend a couple of hundred dollars a year in diesel. Nothing really.

For the sake of a cost example, it might cost 80k to spec up a solar system that can handle a house, workshop lights etc, plus high draw machinery.

The cost of down spec'ing the solar system to normal house requirements and up spec'ing the backup generator so it handles those short periods of high load when using a larger piece of machinery, might cost 40k.

Anyway, I don't have any numbers to confirm that yet. Just a though

Cheers

Greg

Greg

firstly I'm not a sparky

However, in the past I've had the joy of managing a camp powered by diesel generators.

Solar power is possible but as others have said it wont be cheap and for 3 phase the system wont be small — you may find that your total roof area is not large enough to fit all the panels you would need.

Remember because you are "remote" you'll probably only go to the shops once or twice a month.
This implies a largish fridge, freezer and possibly a cool room to store up to a month's worth of food.
Also, will the missus want air con in the house?

then to the workshop ...
assume that you have
an air cleaner running for at least an hour after you turn any machinery off and possibly for an hour after you shut the door
a 5hp plumbed dust extractor that runs for say 5 mins after you turn the saw / shaper / jointer / thicknesser off
5 hp motors on the big tools
up to 2.5 hp at a time with the smaller tools

on this basis it would not be unreasonable to assume a steady state current draw approaching 40 amps (dusty, thicknesser, air cleaner, lights) with starting currents a lot higher add to this the frdge or freezer kicking-in
a battery backed solar system would have to be sized to accomodate all this even if the peak current draw is only for a few minutes – otherwise you'll spend your entire day resetting breakers or replacing blown fuses


oh, and how hot will it be in the shed? will you want/need cooling or heating


now to something I know a bit about – running that lot off a diesel generator

what is critical is matching the generator to the load – ideally you want the generator running long term at 80–90% capacity
if you're load is too low, there is significant risk of the glazing the cylinders in the generator – $$ to fix and no power till it is
For 3 phase power I'd recommend a 3 phase generator, but if you also connect it to the house you could have a devil of a job balancing the load around the phases
which might imply 2 or even 3 generators (1, 3 phase for the big tools, the others single phase for the house and smaller stuff in the shed)

My recollection of the "joys" of attempting to run a camp off 2 x 60 kVA 3 phase generators was that it was this "easier" to get the equivalent power output from a number of single phase 10 kVA generator, turning them off as the load dropped overnight.


Thinking about the high cost of running power in the recent past, this will have been driven somewhat by the high price of copper and aluminium. With the economic downturn, metal prices have collapsed somewhat, potentially making long cable runs (I recommend HV overhead wire to a transformer in the yard) much cheaper




ian

These dudes here live off grid in the Rockies and power there houses from wind turbines they design and build them selves but there is lots of general info about off grid living and plenty of interesting reading.

http://www.otherpower.com/otherpower_solar.html

Originally Posted by Zed

"efficient" is a relative term. internal combustion engines (whatever fuel method you choose) hover about 40% efficiency (I think - I should check but couldnt be bothered).the most efficient machine men make is a bicycle - energy transfer is up near 90% i believe.

There's a pretty big loss whenever energy gets converted from one form to another. I don't have any numbers, I tried to update my memory (I left school in '65, haven't updated them since), but here's a list of likely conversions. In mains power; you should add in transmission losses.

Fuel to heat water (stored to heat)
Steam to drive turbine (heat to another kinetic)
Turbine/generation plant to generate electricity (kinetic to electricity)
Transformer (Electricity to electricity)
Electric motor (electricity to kinetic)

If you're using solar, you lose a fair bit when
converting sun rays to electricity
Storing energy (charging batteries)
Taking energy from storage (discharging batteries)
Converting DC to AC. Probably more if generating 3-phase.
Changing voltage (transformer).

As I said, I don't recall the numbers, but I think any conversion lost 40% or more. Even at 10% loss, there's a lot of ten percents.

Fuel cells do pretty well, all things considered: it's pretty similar to using precharged batteries, and while recent news has been based on their using hydrogen as their fuel, they can use other fuels including hydrocarbons.

I remember reading in the 60s that some farmer got quite a deal of fuel from his piggery - all that manure which he used to generate methane, and there are fuel cells can use methane. The residue is pretty good on the garden

You are absolutely correct, John, but the true believers do not like looking at the numbers.

Commercially available photovoltaic units only have an efficiency of about 15% under ideal conditions, but in reality rarely operate above 10%. They require bright sunshine, no shadows, perfect alignment with a moving sun, and they lose efficiency if their surface temperature exceeds 25*C. Yes, they work off sunlight but do not like heat. And once you run that electricity through a battery you lose at least 20%.

Solar power is very expensive electricity.

As to fuel cells, where can you buy one? They may be the product of the future but the technology is not yet out of the laboratory.

Cheers

Graeme