I'm currently planning how to change all our domestic lighting to 12v.
I've got most of the battery and useage side sorted out:
Four lighting circuits (upstairs bedrooms, downstairs bedroom and two living rooms, downstairs kitchen and dining room, downstairs lobbies and bathroom).
These would be wired into a six-way panel with rocker switches, LED warning lamps and six fuses holders (probably 15A fuses). With four lighting circuits, I'd have two spare slots on the panel for future lighting or appliances (I'm looking at 12v central heating pumps for example).
This would be wired into a three-way battery change-over switch (I'd have two battery banks so there's no single point of failure, so the switch would be Both Banks, Bank 1, Bank 2 and off).
There would be two battery banks (gel batteries, either 12V or - if a source comes through - lots of 2V 20-year life expectancy batteries wired to give 12V).
I also have the energy sources sorted - a combination of PV, 48v wind turbine (due to the distance from the hilltop to the battery bank in insualted loft), WVO-fuelled diesel generator (with possibility of methane from pig and chicken manure in future) that has both 240V AC and 12V DC output, and grid.
Ideally, the battery banks would be kept charged by wind and PV, with the grid cutting in when the charge was down but both wind and PV weren't providing power. If the grid was also down, then an a visible and audible alert would sound so I could start the generator. I'd have a monitoring and control panel downstairs, probably in the kitchen.
One thing I don't want is a single point of failure.
Where I'm stuck at the moment is the right combination of battery charging, inverter (so that in the event of a power failure I can still run a couiple of 240v appliances), regulation, power sharing and monitoring. I've been in touch with a few companies, but can't get much in agreement!
I've had a combined inverter-charger with in-built solar regulator suggested (as used on some yachts and narrow boats), but this does seem to put all your eggs in one basket. Of course, I could always have one spare but...
Any thoughts would be appreciated. (Oh, and don't worry about exact numbers at this point as I'm still working out the exact lighting combination, plus an allowance for appliances in the future.)
12v domestic electrical systems
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Martin
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the first thing that springs to mind is "why 12v for the lighting?" - it means you've got to use some pretty hefty cabling for it as the current is high - many people nowadays use their ordinary mains circuitry, and run an inverter for the lights - 240v bulbs are also a heck of a lot cheaper than their 12v equivalents.
If you want true "belt and braces", I guess you'd go for the battery banks as "reservoirs", and feed all the power into them until fully charged, then either export any excess to the grid through a grid-tie inverter, or have a suitable immersion heater - that way you've got a fully charged battery bank if the mains fails. There are fairly simple split-charge devices that will allow the charging of two banks of batteries
If you went the grid-tie route, it may pay you to look at something like a 48 volt battery bank - you're talking a heck of a lot of current to feed household items like washing machines at 12v, so a higher voltage can make things loads cheaper and easier to wire (but you're dependant on your inverter)
There are so many variables that there are umpteen different configurations that could work - it's just doing all the sums, and trying to design it around your wants and needs! - I'll mull it over, and see if I can think up!
What would help is a rough idea of what you'd need to run at 240v in the event of a prolonged power cut, a rough estimate of your lighting use,
and if possible what your present electricity useage is!
If you want true "belt and braces", I guess you'd go for the battery banks as "reservoirs", and feed all the power into them until fully charged, then either export any excess to the grid through a grid-tie inverter, or have a suitable immersion heater - that way you've got a fully charged battery bank if the mains fails. There are fairly simple split-charge devices that will allow the charging of two banks of batteries
If you went the grid-tie route, it may pay you to look at something like a 48 volt battery bank - you're talking a heck of a lot of current to feed household items like washing machines at 12v, so a higher voltage can make things loads cheaper and easier to wire (but you're dependant on your inverter)
There are so many variables that there are umpteen different configurations that could work - it's just doing all the sums, and trying to design it around your wants and needs! - I'll mull it over, and see if I can think up!
What would help is a rough idea of what you'd need to run at 240v in the event of a prolonged power cut, a rough estimate of your lighting use,
and if possible what your present electricity useage is!
http://solarwind.org.uk - a small company in Sussex sourcing, supplying, and fitting alternative energy products.
Amateurs encouraged - very keen prices and friendly helpful service!
Amateurs encouraged - very keen prices and friendly helpful service!
Running anything through an inverter uses heaps of 12 volt power - we use all 12 volt direct ligthing in the house!
Nev
Nev
Garden shed technology rules! - Muddypause
Our website on living more sustainably in the suburbs! - http://www.underthechokotree.com/
Our website on living more sustainably in the suburbs! - http://www.underthechokotree.com/
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Stonehead
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I have thought this through and to reiterate:
1. Many of the existing 240v light circuits in the house are dodgy and need to be replaced anyway. The quite recent light circuit upstairs is so bad that the lights flicker, go off for periods then come on again, and the wiring hums. In the kitchen, I've found appliance flex was used!
2. I could change the 240v wiring myself, but this is inadviseable given the new regulations and certification should we come to sell (hopefully not, but...). Electricians who will do the job for us are impossible to find and, if we could find them, would cost. With 12v DC I can do it myself and not worry about the regulations.
3. We already have a generator with both 230-250v AC and 24v DC output. We also want solar and wind, which both output DC. To keep things as efficient as possible, I think it makes sense to keep everything DC where possible.
4. We have no intention of using 12v for washing machines and other large appliances. Lights, some hard wired appliances (like a central heating pump for example), and appliances that already use 12v but via a transformer would be the main things. For the short-term to mid-term, the larger appliances and my tools will be run off mains (or directly by the generator in a blackout), but in the longer term we want fewer 240 appliances plus the most efficient inverter we can find for those that we can't replace.
5. Our electricity supply here is already unreliable. We have an old power line that crosses our land, the posts are overdue for replacement and blackouts are frequent. Long blackouts are not unknown. Our main requirements in a blackout are lights, the central heating pump, the freezers and the electric fence.
6. Long-term, we want to move to a position where we can be independent of the grid at the flick of a switch. That means planning our system now and doing it in such a way that we can change parts of the system as we go. We'd like to move to a position where the grid is simply one of the inputs to our power supply and distribution system (wind, solar, grid, generator) with the idea being that we can readily withstand the failure or absence of any two and cope with the failure of absence of any three.
7. While putting the existing central heating pump on a UPS is a good idea, it looks even better to replace the pump (which is old) with a 12v one and wire that into the 12v system.
8. None of the DC cable runs would be longer than twice the length of large narrow boat (120ft) and most would be considerably shorter. We'd go for the thickest cable and keep the number of lights/appliances on each circuit to four or less.
9. The system has to be as efficient as possible so the less power than has to go through an inverter, the better.
10. As for our current power consumption, I can't give stable figures at the moment as we're managing down appliance by appliance and, in any case, I think this is the wrong way around. What I'm doing in working out our new system is working out the amount of light needed in each room, then finding the right lighting combination to achieve that and then the amount of power needed. The same with appliances - work out what we actually need (as opposed to have or inherited with the house), then find the most efficient solution, and then calculate the power. Then add everything up, add 10-20% overcapacity for a bit of give, for losses and for inefficiencies, then configure the battery bank and energy inputs to provide that.
So, as I said I'm not looking for specific solutions at the moment (this will come when I have the power consumption calculated). What I am looking for is some idea as to the right combination of charging, inverting, regulating, sharing and monitoring so when I have the figures I can then look for the specific parts to build the system.
I'm at the concept brief stage, rather than the engineering brief stage.
So, do I run everything through one box (which to me means one very expensive bit of kit and single point of failure), or through a series of boxes (less expensive to replace individually and multiple points of failure but easily diagnosed by me).
So, inputs would be:
Wind - primary source, 48v due to the cable run from the hill, charging the battery banks or dumping load (either to water immersion heater or to the WVO tank heating system).
Solar - secondary source, particularly in summer when the wind is less strong, charging the the battery banks.
Grid - at this point, supplying appliances via existing circuits and charging battery banks if they're low and other sources are not charging.
Generator - at this point, supplying key appliances in blackouts and charging battery banks in blackouts if they're low.
Longer term, and depending on the cost of fuel for the generator versus the cost of electricity, the generator and grid may swap priority in the system.
Have to leave it at that as I have to go and finish building the pig creep before Delilah farrows.
1. Many of the existing 240v light circuits in the house are dodgy and need to be replaced anyway. The quite recent light circuit upstairs is so bad that the lights flicker, go off for periods then come on again, and the wiring hums. In the kitchen, I've found appliance flex was used!
2. I could change the 240v wiring myself, but this is inadviseable given the new regulations and certification should we come to sell (hopefully not, but...). Electricians who will do the job for us are impossible to find and, if we could find them, would cost. With 12v DC I can do it myself and not worry about the regulations.
3. We already have a generator with both 230-250v AC and 24v DC output. We also want solar and wind, which both output DC. To keep things as efficient as possible, I think it makes sense to keep everything DC where possible.
4. We have no intention of using 12v for washing machines and other large appliances. Lights, some hard wired appliances (like a central heating pump for example), and appliances that already use 12v but via a transformer would be the main things. For the short-term to mid-term, the larger appliances and my tools will be run off mains (or directly by the generator in a blackout), but in the longer term we want fewer 240 appliances plus the most efficient inverter we can find for those that we can't replace.
5. Our electricity supply here is already unreliable. We have an old power line that crosses our land, the posts are overdue for replacement and blackouts are frequent. Long blackouts are not unknown. Our main requirements in a blackout are lights, the central heating pump, the freezers and the electric fence.
6. Long-term, we want to move to a position where we can be independent of the grid at the flick of a switch. That means planning our system now and doing it in such a way that we can change parts of the system as we go. We'd like to move to a position where the grid is simply one of the inputs to our power supply and distribution system (wind, solar, grid, generator) with the idea being that we can readily withstand the failure or absence of any two and cope with the failure of absence of any three.
7. While putting the existing central heating pump on a UPS is a good idea, it looks even better to replace the pump (which is old) with a 12v one and wire that into the 12v system.
8. None of the DC cable runs would be longer than twice the length of large narrow boat (120ft) and most would be considerably shorter. We'd go for the thickest cable and keep the number of lights/appliances on each circuit to four or less.
9. The system has to be as efficient as possible so the less power than has to go through an inverter, the better.
10. As for our current power consumption, I can't give stable figures at the moment as we're managing down appliance by appliance and, in any case, I think this is the wrong way around. What I'm doing in working out our new system is working out the amount of light needed in each room, then finding the right lighting combination to achieve that and then the amount of power needed. The same with appliances - work out what we actually need (as opposed to have or inherited with the house), then find the most efficient solution, and then calculate the power. Then add everything up, add 10-20% overcapacity for a bit of give, for losses and for inefficiencies, then configure the battery bank and energy inputs to provide that.
So, as I said I'm not looking for specific solutions at the moment (this will come when I have the power consumption calculated). What I am looking for is some idea as to the right combination of charging, inverting, regulating, sharing and monitoring so when I have the figures I can then look for the specific parts to build the system.
I'm at the concept brief stage, rather than the engineering brief stage.
So, do I run everything through one box (which to me means one very expensive bit of kit and single point of failure), or through a series of boxes (less expensive to replace individually and multiple points of failure but easily diagnosed by me).
So, inputs would be:
Wind - primary source, 48v due to the cable run from the hill, charging the battery banks or dumping load (either to water immersion heater or to the WVO tank heating system).
Solar - secondary source, particularly in summer when the wind is less strong, charging the the battery banks.
Grid - at this point, supplying appliances via existing circuits and charging battery banks if they're low and other sources are not charging.
Generator - at this point, supplying key appliances in blackouts and charging battery banks in blackouts if they're low.
Longer term, and depending on the cost of fuel for the generator versus the cost of electricity, the generator and grid may swap priority in the system.
Have to leave it at that as I have to go and finish building the pig creep before Delilah farrows.
Stonehead, I am convinced that 12v is the way to go. Part of the process is giving up on power hungry items. Pedal the washing machine etc.
2 days ago I had a consumer unit failure, a burn out. I decided that the consumer replacement was a bit beyond my capability also going to sell up some time. I spent a day and a night off the grid. I have a small generator that powered up a small kettle and a string of low energy light bulbs. A gas fire, and two lights run from batteries. A 12v draper under bonnet strip light was very efficient giving lots of light from its 8w flluorescent tube. (has a reflecting surface added to the light) I thought these tubes if readily available are very good and appeared better than some low energy 240v lights.
Are leisure or deep cycle batteries needed? Example, I have two 100ah elecsols very pricy at £85 each. About twice the cost of standard batteries. An auto electrician selling batteries and battery chargers say's there is a lot of hype with leisure/deep cycle batteries, in most cases standard vehicle batteries make more sense. If you don't run the batteries to low, perhaps, are they practical, do you think?
John
2 days ago I had a consumer unit failure, a burn out. I decided that the consumer replacement was a bit beyond my capability also going to sell up some time. I spent a day and a night off the grid. I have a small generator that powered up a small kettle and a string of low energy light bulbs. A gas fire, and two lights run from batteries. A 12v draper under bonnet strip light was very efficient giving lots of light from its 8w flluorescent tube. (has a reflecting surface added to the light) I thought these tubes if readily available are very good and appeared better than some low energy 240v lights.
Are leisure or deep cycle batteries needed? Example, I have two 100ah elecsols very pricy at £85 each. About twice the cost of standard batteries. An auto electrician selling batteries and battery chargers say's there is a lot of hype with leisure/deep cycle batteries, in most cases standard vehicle batteries make more sense. If you don't run the batteries to low, perhaps, are they practical, do you think?
John
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titch7069
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have you checked out www.ankurscientific.com ? we have a small gasifier, as a back up to the solar, admittedly we have slightly more sun than you but we do have 2 rainy seasons! for the lodge we intend to get a GAS-11 which will power the whole thing, fantastic insert wood it converts to clean gas which powers a genset, and its cheap.
Have sold up in the UK, now living on Mafia Island, in the middle of an old coconut plantation. We catch our fish, have chickens, grow fruit and veg. We are powered by solar and an ankur gasifier - no mains elec here!!
My blog is at www.travelblog.org/Bloggers/titch
My blog is at www.travelblog.org/Bloggers/titch
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Martin
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on batteries! - car batteries are a TOTAL nono! - they really aren't designed for deep cycling, and have a ridiculously short life if used for these sorts of exercise. There are several schools of thought on batteries, many say buy the cheapest genuine flooded lead-acid deep cycle batteries you can find, others swear by gel batteries - you have to be particularly careful not to overcharge gels, but they are to my mind the preferable option - they will take a genuinely deep discharge now and again without any great harm, and if not regularly deeply discharged should last around ten years. The best price I've found is Advanced Glass Mat deep cycle batteries at 65 quid for 110 amps
http://solarwind.org.uk - a small company in Sussex sourcing, supplying, and fitting alternative energy products.
Amateurs encouraged - very keen prices and friendly helpful service!
Amateurs encouraged - very keen prices and friendly helpful service!
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Muddypause
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I've heard of people using ex-submarine batteries with success. Not sure if they're 12 volt, though, or where you would source them from.
I guess they would be very well suited to this purpose, though, since thay are intended to supply all the sub's needs when it is underwater. I suspect you would get a lot of battery for your money, this way.
I guess they would be very well suited to this purpose, though, since thay are intended to supply all the sub's needs when it is underwater. I suspect you would get a lot of battery for your money, this way.
Stew
Ignorance is essential
Ignorance is essential
Martin the glass matt type batteries at £65 sound like a good deal and perhaps similar to the elecsols that have some sort of carbon mat technology. I thought your £45 batteries looked good value, not suitable for hooking up to wind/solar? tempting at that price.
Titch You have taken a very brave step, from Ramsgate. I will have a good read, looks good enough to go into a book. thanks.
John
Titch You have taken a very brave step, from Ramsgate. I will have a good read, looks good enough to go into a book. thanks.
John
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camillitech
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hi stoney, nothing wrong with 12v i lived with it as my primary power source for 20years. running a lister twice a week to do the washing and top up the batteries when my rutland 910 was struggling. nowadays you can get 12v everything as i'm sure you know. things have moved on for me now the rutland finaly died after several sets of bearings,blades,etc and we now have a proven 2.5kw turbine which gives us more power than we know what to do with! we even have an electric oven and tumble dryer now. i spent months researching inverter/chargers and there is only one as far as i'm concerned and thats a 'TRACE' (mines a 48v4.5kw) and it will do everything you want and more. others may appear to do the same for half the price but trust me they don't . i nearly bought a 'STUDER' as it seemed well made an it's swiss (well they make good watches don't they) my freind bought one 2 years ago and he still can't get it to autostart his genny, now he's scared of touching it as everytime he does he loses all his settings and has to reprogram it (and he,s not alone) the trace is idiot proof (well it's american). i'm sure a 2.5kw trace would be just what you need, it even has inputs for both grid and genny.
cheers paul
cheers paul
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Stonehead
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Paul,camillitech wrote:hi stoney, nothing wrong with 12v i lived with it as my primary power source for 20years. running a lister twice a week to do the washing and top up the batteries when my rutland 910 was struggling. nowadays you can get 12v everything as i'm sure you know. things have moved on for me now the rutland finaly died after several sets of bearings,blades,etc and we now have a proven 2.5kw turbine which gives us more power than we know what to do with! we even have an electric oven and tumble dryer now. i spent months researching inverter/chargers and there is only one as far as i'm concerned and thats a 'TRACE' (mines a 48v4.5kw) and it will do everything you want and more. others may appear to do the same for half the price but trust me they don't . i nearly bought a 'STUDER' as it seemed well made an it's swiss (well they make good watches don't they) my freind bought one 2 years ago and he still can't get it to autostart his genny, now he's scared of touching it as everytime he does he loses all his settings and has to reprogram it (and he,s not alone) the trace is idiot proof (well it's american). i'm sure a 2.5kw trace would be just what you need, it even has inputs for both grid and genny.
cheers paul
Thanks, that's the sort of practical information I was after. Very helpful.
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camillitech
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morning stoney
just a few of my thoughts/experiences with batteries here. if you're going to use an inverter/charger steer clear of gel/carbon/spiral/sealed batteries as they don't like the high charge rates. you need deep cycle lead/acid traction batteries (as in forklift truck, golf cart, and probably submarine) and whilst ni cads may last forever their slightly lower voltage makes them hopeless for lighting(well flourescents at least) the fancy batteries are fine if you want to turn them upside down, eat off them, cram them into a small place or submerge them but for a domestic system you culd get twice as many amphours per £ out of a traction battery.
paul
just a few of my thoughts/experiences with batteries here. if you're going to use an inverter/charger steer clear of gel/carbon/spiral/sealed batteries as they don't like the high charge rates. you need deep cycle lead/acid traction batteries (as in forklift truck, golf cart, and probably submarine) and whilst ni cads may last forever their slightly lower voltage makes them hopeless for lighting(well flourescents at least) the fancy batteries are fine if you want to turn them upside down, eat off them, cram them into a small place or submerge them but for a domestic system you culd get twice as many amphours per £ out of a traction battery.
paul
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Stonehead
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What about deep cycle gel marine batteries as used in submarines and for bow thrusters on tugs etc? Maintenance free, leak free and designed for long, sustained power discharge. I'm thinking of the ones from Sonnenschein or Energy Gel.camillitech wrote:morning stoney
just a few of my thoughts/experiences with batteries here. if you're going to use an inverter/charger steer clear of gel/carbon/spiral/sealed batteries as they don't like the high charge rates. you need deep cycle lead/acid traction batteries (as in forklift truck, golf cart, and probably submarine) and whilst ni cads may last forever their slightly lower voltage makes them hopeless for lighting(well flourescents at least) the fancy batteries are fine if you want to turn them upside down, eat off them, cram them into a small place or submerge them but for a domestic system you culd get twice as many amphours per £ out of a traction battery.
paul
I can get deep cycle marine batteries through a contact in the oil industry at very good prices.