Solar energy vs Mains argument
Mar 14th 2007, 11:20 am
#1
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Joined: Mar 2006
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Solar energy vs Mains argument
Appologies in advance for the length of this posting, but there are so many different issues with living off-grid.
For anyone that is interested in the Solar energy vs Mains argument - I can't speak for anyone else, I can only explain how my house works and what it costs.
You can buy solar panels for around 3.40Euros per Watt. Lets say you're on a budget and decide to invest in 600W of panels. Immediately you're 2 grand out of pocket.
600 Watts I hear you shout, that won't even run my hairdryer!
Most panels are either 12V or 24V. You don't have to buy 20 12V panels or 10 24V panels to get your 220/240V appliances to work. You can buy just one or two at a time to suit your budget and extend your solar capacity over time as and when the need arises. That's the beauty of small solar systems - you only buy what you need and can afford. The thing to remember is that your house is effectively running off batteries and the solar panels are simply a battery charger. You can include other types of battery charger in your off-grid setup, such as a wind turbine or a petrol/diesel generator.
You can have as few or as many batteries as you like. Obviously the more batteries you have then the more power you can store. But even with one basic car battery you can run a standard tv/dvd, electric lights, anything really. If the battery is fully charged then you should get several hours of watching tv before the power runs out.
Ah but, I hear you cry, a car battery only produces 12V and my tv requires 220/240V, so you're obviously talking rubbish!
Not so, says I. Your car battery is simply connected to a power inverter whch turns 12V into 220/240V. A power inverter can cost as much as you want it to. You can buy a 600W modified sine wave inverter for under £70 from Maplins in England. This will easily run your tv/dvd and lighting.
Batteries are a science unto themselves and car batteries, while being cheap to buy and ok for a few months of use, will not last long and are really a false economy. There are many different types of batteries but the ones designed for solar systems are much better and should last five to ten years at least. We paid about 250Euros for a reasonable 220AH solar battery.
So lets say you buy four solar batteries. That's another grand gone, but you now have about 880 AmpHours worth of storage capacity.
Power inverters are another expense. Yes, that cheap 600W inverter from Maplins will actually go a long way, but what about that 1KW hairdryer you so desperately want to use? Well there are two types of inverter - true sine wave and modified sine wave. True sine wave inverters are better, more efficient and much more expensive. However, search around and you can pick up a new 1500W true sine wave inverter that includes battery charge controller and 50W battery charger from some of the ebay shops for around 750Euros delivered.
So what have we spent so far?
Solar Panels - 2000E
Batteries - 1000E
Inverter - 750E
Total 3750E
But what can I run with this setup?
Well, lets work it out being very simplistic with the figures.
600W of panels for 6 hours direct sunlight produces around 3600W of power per day. That's 3.6KW of power per day going into your batteries.
Lets say you watch about 4 hours tv every night. A modern tv might use around 100W of power, dvd players only use about 15W, so thats about 460W per day.
Buy the energy efficient light bulbs and you use 11W instead of 60W per bulb. Say you run about 4 bulbs at any one time for about 4 hours per night (and that's a heck of a lot more than my family of four use on an evening). That works out at about 180W per day.
So we've used up about 640W out of 3600W so far.
Lets switch that hairdryer on and let the whole family enjoy it for a full hour. Now we're up to 1640W out of 3600W.
What else uses electricity? The iron - big power user, but only when it's in its heating phase. Maybe 1.3KW. Even if you do the ironing for an hour it doesn't actually use that 1.3KW all the time.
The fridge -
The electric fridge is a fairly big consumer of electricity. A typical class A rated fridge/freezer uses about 1kw per day. You could run an electric fridge off this system as well, but it is a big chunk of your available power. But gas fridge/freezers are extremely efficient and almost totally silent. A modern gas fridge looks virtually identical to any electric one. It costs us about 10 Euros per month in gas to run our fridge/freezer.
Looking at these figures it would seem that we've got so much power to spare. However, the observant of you might have realised we only have a 1500W inverter. Plug that iron in while little billy is blow-drying his hair and that inverter is going to squeal. And where does all the ironing come from? We haven't run the washing machine yet!
Washing machines are big power users. No problem if you do a cold wash - only a few hundred watts of power. Try a hot wash and your 1500W inverter may not like it. The solution? get a bigger inverter or switch the backup generator on when you run the washing machine. What backup generator, we hear you ask? The one you bought with the spare 1250Euros from your initial 5000E. Of course, when you run the generator, the batteries also get a very good top-up from the 50W battery charger built into your inverter.
Unfortunately, a good generator is essential because there will always be those times when you get several days in a row of cloud and rain and by the third day your batteries are getting a bit low. Or you have a party and every light in the house is blazing, outside lights are on, stereo blasting out 500W, and you're trying like hell to get your hair blow-dryed in time for the first guests.
The thing about being off-grid is that you become very aware of how much power you are actually consuming. And that's a good thing. You automatically switch off lights when you leave the room. You don't leave the tv/stereo/computer switched on or on standby when you aren't using it. On the negative side, you can't do the ironing when Billy is using the hairdryer. You have to think a little. But at least you don't have to pay a standing charge and then a monthly/quarterly bill on top of that, nor be at the mercy of the electric companies when they decide to upgrade the transformer at the end of the road and cut you off without warning for three days.
5000Euros might seem like a big investment, but solar panels are typically guaranteed for twenty years - they don't go wrong. Batteries have to be replaced maybe every ten years or so. You have to buy petrol or diesel for the genny, but you will probably find that one twenty litre jerry can of diesel lasts for months throughout the summer.
I have neighbours who are desperately waiting for mains electricity to come to our area. They have a generator and nothing else. They spend a fortune on fuel and as soon as the sun goes down they either go to bed or have to switch the genny on. But mention solar to them and they cover their ears and refuse to even think about it. It makes me smile though when at dusk I hear in the distance their generators firing up, and as I switch the lights on and watch a bit of tv powered by my free, clean electricity supply I think about how much I don't have to spend buying more fuel.
For anyone that is interested in the Solar energy vs Mains argument - I can't speak for anyone else, I can only explain how my house works and what it costs.
You can buy solar panels for around 3.40Euros per Watt. Lets say you're on a budget and decide to invest in 600W of panels. Immediately you're 2 grand out of pocket.
600 Watts I hear you shout, that won't even run my hairdryer!
Most panels are either 12V or 24V. You don't have to buy 20 12V panels or 10 24V panels to get your 220/240V appliances to work. You can buy just one or two at a time to suit your budget and extend your solar capacity over time as and when the need arises. That's the beauty of small solar systems - you only buy what you need and can afford. The thing to remember is that your house is effectively running off batteries and the solar panels are simply a battery charger. You can include other types of battery charger in your off-grid setup, such as a wind turbine or a petrol/diesel generator.
You can have as few or as many batteries as you like. Obviously the more batteries you have then the more power you can store. But even with one basic car battery you can run a standard tv/dvd, electric lights, anything really. If the battery is fully charged then you should get several hours of watching tv before the power runs out.
Ah but, I hear you cry, a car battery only produces 12V and my tv requires 220/240V, so you're obviously talking rubbish!
Not so, says I. Your car battery is simply connected to a power inverter whch turns 12V into 220/240V. A power inverter can cost as much as you want it to. You can buy a 600W modified sine wave inverter for under £70 from Maplins in England. This will easily run your tv/dvd and lighting.
Batteries are a science unto themselves and car batteries, while being cheap to buy and ok for a few months of use, will not last long and are really a false economy. There are many different types of batteries but the ones designed for solar systems are much better and should last five to ten years at least. We paid about 250Euros for a reasonable 220AH solar battery.
So lets say you buy four solar batteries. That's another grand gone, but you now have about 880 AmpHours worth of storage capacity.
Power inverters are another expense. Yes, that cheap 600W inverter from Maplins will actually go a long way, but what about that 1KW hairdryer you so desperately want to use? Well there are two types of inverter - true sine wave and modified sine wave. True sine wave inverters are better, more efficient and much more expensive. However, search around and you can pick up a new 1500W true sine wave inverter that includes battery charge controller and 50W battery charger from some of the ebay shops for around 750Euros delivered.
So what have we spent so far?
Solar Panels - 2000E
Batteries - 1000E
Inverter - 750E
Total 3750E
But what can I run with this setup?
Well, lets work it out being very simplistic with the figures.
600W of panels for 6 hours direct sunlight produces around 3600W of power per day. That's 3.6KW of power per day going into your batteries.
Lets say you watch about 4 hours tv every night. A modern tv might use around 100W of power, dvd players only use about 15W, so thats about 460W per day.
Buy the energy efficient light bulbs and you use 11W instead of 60W per bulb. Say you run about 4 bulbs at any one time for about 4 hours per night (and that's a heck of a lot more than my family of four use on an evening). That works out at about 180W per day.
So we've used up about 640W out of 3600W so far.
Lets switch that hairdryer on and let the whole family enjoy it for a full hour. Now we're up to 1640W out of 3600W.
What else uses electricity? The iron - big power user, but only when it's in its heating phase. Maybe 1.3KW. Even if you do the ironing for an hour it doesn't actually use that 1.3KW all the time.
The fridge -
The electric fridge is a fairly big consumer of electricity. A typical class A rated fridge/freezer uses about 1kw per day. You could run an electric fridge off this system as well, but it is a big chunk of your available power. But gas fridge/freezers are extremely efficient and almost totally silent. A modern gas fridge looks virtually identical to any electric one. It costs us about 10 Euros per month in gas to run our fridge/freezer.
Looking at these figures it would seem that we've got so much power to spare. However, the observant of you might have realised we only have a 1500W inverter. Plug that iron in while little billy is blow-drying his hair and that inverter is going to squeal. And where does all the ironing come from? We haven't run the washing machine yet!
Washing machines are big power users. No problem if you do a cold wash - only a few hundred watts of power. Try a hot wash and your 1500W inverter may not like it. The solution? get a bigger inverter or switch the backup generator on when you run the washing machine. What backup generator, we hear you ask? The one you bought with the spare 1250Euros from your initial 5000E. Of course, when you run the generator, the batteries also get a very good top-up from the 50W battery charger built into your inverter.
Unfortunately, a good generator is essential because there will always be those times when you get several days in a row of cloud and rain and by the third day your batteries are getting a bit low. Or you have a party and every light in the house is blazing, outside lights are on, stereo blasting out 500W, and you're trying like hell to get your hair blow-dryed in time for the first guests.
The thing about being off-grid is that you become very aware of how much power you are actually consuming. And that's a good thing. You automatically switch off lights when you leave the room. You don't leave the tv/stereo/computer switched on or on standby when you aren't using it. On the negative side, you can't do the ironing when Billy is using the hairdryer. You have to think a little. But at least you don't have to pay a standing charge and then a monthly/quarterly bill on top of that, nor be at the mercy of the electric companies when they decide to upgrade the transformer at the end of the road and cut you off without warning for three days.
5000Euros might seem like a big investment, but solar panels are typically guaranteed for twenty years - they don't go wrong. Batteries have to be replaced maybe every ten years or so. You have to buy petrol or diesel for the genny, but you will probably find that one twenty litre jerry can of diesel lasts for months throughout the summer.
I have neighbours who are desperately waiting for mains electricity to come to our area. They have a generator and nothing else. They spend a fortune on fuel and as soon as the sun goes down they either go to bed or have to switch the genny on. But mention solar to them and they cover their ears and refuse to even think about it. It makes me smile though when at dusk I hear in the distance their generators firing up, and as I switch the lights on and watch a bit of tv powered by my free, clean electricity supply I think about how much I don't have to spend buying more fuel.
Mar 14th 2007, 11:31 am
#2
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Joined: Feb 2005
Posts: 300
Re: Solar energy vs Mains argument
Great post. Do you know if your supplier also does solar power systems for motorhomes? 3.40€ per watt, is a very appealing price.
Mar 14th 2007, 11:37 am
#3
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Joined: Apr 2006
Location: Jerez de la Frontera
Posts: 1,656
Re: Solar energy vs Mains argument
Excellent post billgates - nicely explained for the idiots like me who have no idea how these things work!
One question though - what about air-conditioning? Is that a big consumer of power - I guess it must be?
One question though - what about air-conditioning? Is that a big consumer of power - I guess it must be?
Mar 14th 2007, 12:01 pm
#4
In Estepona
Joined: Feb 2007
Location: Estepona, Spain
Posts: 633
Re: Solar energy vs Mains argument
I guess we can only hope for solar power equipment to come down in price so more and more people would use it. Espeically in spain with all the sun that they get youd think itd be almost standard.
Very good read though and although theres an inital investment it does sound like that youre saving money in the long term and the environment.
Very good read though and although theres an inital investment it does sound like that youre saving money in the long term and the environment.
Mar 14th 2007, 12:27 pm
#5
Not Junior but not Senior
Joined: Oct 2005
Posts: 1,052
Re: Solar energy vs Mains argument
Excellent post Bill. What about the possibility of using 24V ? Is there an advantage?? In places like Chiclana which have bouts of very strong winds, would not factoring a wind genny into the equation help?? They are even selling simple wind gennys in B & Q. I know they can be noisy on a boat, and the vibration can be a nuisance, but given a large enough plot they could be situated away from the house.
Mar 14th 2007, 12:37 pm
#6
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Joined: Mar 2006
Posts: 827
Re: Solar energy vs Mains argument
I don't know anything about motorhomes, but a solar panel is the same whether it's mounted on a house roof or a vehicle roof - you just buy the size and wattage you require.
To be honest, I've found ebay to be the best source for solar panels - the wholesaler that quoted me 3.40€ has an ebay site (can't find the web address at the moment).
I managed to buy a new 120W panel on ebay for 3.20€ per watt from a company called Solartes but they don't seem to have anything on ebay at the moment.
Mar 14th 2007, 12:51 pm
#7
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Thread Starter
Joined: Mar 2006
Posts: 827
Re: Solar energy vs Mains argument
Excellent post Bill. What about the possibility of using 24V ? Is there an advantage?? In places like Chiclana which have bouts of very strong winds, would not factoring a wind genny into the equation help?? They are even selling simple wind gennys in B & Q. I know they can be noisy on a boat, and the vibration can be a nuisance, but given a large enough plot they could be situated away from the house.
Some of the better true sine wave inverters are switchable 12/24V, some automatically detect the input voltage.
My system is a 12V system at present, but then it's still very small. With more panels added the amount of current (amps) being fed into the 12V batteries would be more than the charge controller can handle. Upgrading to 24V would get around this problem.
Of course, using higher voltages means you don't lose as much in the cables by way of resistance.
As for wind generators - the following is from a posting I made on an older thread....
Basically, if the wind is a nuisance where you are then it could be cost effective, otherwise I'd think carefully before parting with hard-earned cash.
If you get a decent sized machine with a 2m diameter blade swing, then say at about 20mph wind speed, which is a pretty stiff breeze, you might just get about 350W of power.
Of course, the efficiency of the machine has a lot to do with the amount of power you get, but there is a pretty simple formula to calculate how much a wind generator can produce -
Power(W) = 0.5 x air density x blade sweep area(m2) x wind velocity(m/s) cubed
where -
air density is about 1.22kg/m3 at sea level
blade sweep area is simply area of a circle (pi x radius squared)
And thanks to Betz Law, this gives you an impossible value that you have to apply an efficiency cooefficient to get a more realistic result - from my research about 25% would be a pretty good system.
But that 350W is only attainable at a constant 20mph wind speed, and the machine efficiency will vary up or down either side of it's most efficent velocity.
Also, a lot of wind generators will only start to produce electricity if the wind speed is over a certain amount (maybe 5-6 mph) regardless of whether the blades are actually turning.
Smaller machines are just as inefficient. If you halve the blade diameter you decrease the power output by a factor of four, halve the wind speed and decrease the power by a factor of eight.
The conclusion I came to was that where we live, a wind generator would not justify its initial outlay and that I would be better to get another solar panel. We have very strong gusts of wind occasionally, but these are few and far between.
Cheers,
bill
Mar 14th 2007, 3:40 pm
#8
Forum Regular
Joined: Feb 2005
Posts: 140
Re: Solar energy vs Mains argument
Using 24V would be preferable and more efficient than 12V. 24V Panels cost about the same, but you could always wire a couple of 12V panels in series. Same goes for batteries - whether 12 or 24V, just wire them up accordingly.
Some of the better true sine wave inverters are switchable 12/24V, some automatically detect the input voltage.
My system is a 12V system at present, but then it's still very small. With more panels added the amount of current (amps) being fed into the 12V batteries would be more than the charge controller can handle. Upgrading to 24V would get around this problem.
Of course, using higher voltages means you don't lose as much in the cables by way of resistance.
As for wind generators - the following is from a posting I made on an older thread....
Basically, if the wind is a nuisance where you are then it could be cost effective, otherwise I'd think carefully before parting with hard-earned cash.
If you get a decent sized machine with a 2m diameter blade swing, then say at about 20mph wind speed, which is a pretty stiff breeze, you might just get about 350W of power.
Of course, the efficiency of the machine has a lot to do with the amount of power you get, but there is a pretty simple formula to calculate how much a wind generator can produce -
Power(W) = 0.5 x air density x blade sweep area(m2) x wind velocity(m/s) cubed
where -
air density is about 1.22kg/m3 at sea level
blade sweep area is simply area of a circle (pi x radius squared)
And thanks to Betz Law, this gives you an impossible value that you have to apply an efficiency cooefficient to get a more realistic result - from my research about 25% would be a pretty good system.
But that 350W is only attainable at a constant 20mph wind speed, and the machine efficiency will vary up or down either side of it's most efficent velocity.
Also, a lot of wind generators will only start to produce electricity if the wind speed is over a certain amount (maybe 5-6 mph) regardless of whether the blades are actually turning.
Smaller machines are just as inefficient. If you halve the blade diameter you decrease the power output by a factor of four, halve the wind speed and decrease the power by a factor of eight.
The conclusion I came to was that where we live, a wind generator would not justify its initial outlay and that I would be better to get another solar panel. We have very strong gusts of wind occasionally, but these are few and far between.
Cheers,
bill
Some of the better true sine wave inverters are switchable 12/24V, some automatically detect the input voltage.
My system is a 12V system at present, but then it's still very small. With more panels added the amount of current (amps) being fed into the 12V batteries would be more than the charge controller can handle. Upgrading to 24V would get around this problem.
Of course, using higher voltages means you don't lose as much in the cables by way of resistance.
As for wind generators - the following is from a posting I made on an older thread....
Basically, if the wind is a nuisance where you are then it could be cost effective, otherwise I'd think carefully before parting with hard-earned cash.
If you get a decent sized machine with a 2m diameter blade swing, then say at about 20mph wind speed, which is a pretty stiff breeze, you might just get about 350W of power.
Of course, the efficiency of the machine has a lot to do with the amount of power you get, but there is a pretty simple formula to calculate how much a wind generator can produce -
Power(W) = 0.5 x air density x blade sweep area(m2) x wind velocity(m/s) cubed
where -
air density is about 1.22kg/m3 at sea level
blade sweep area is simply area of a circle (pi x radius squared)
And thanks to Betz Law, this gives you an impossible value that you have to apply an efficiency cooefficient to get a more realistic result - from my research about 25% would be a pretty good system.
But that 350W is only attainable at a constant 20mph wind speed, and the machine efficiency will vary up or down either side of it's most efficent velocity.
Also, a lot of wind generators will only start to produce electricity if the wind speed is over a certain amount (maybe 5-6 mph) regardless of whether the blades are actually turning.
Smaller machines are just as inefficient. If you halve the blade diameter you decrease the power output by a factor of four, halve the wind speed and decrease the power by a factor of eight.
The conclusion I came to was that where we live, a wind generator would not justify its initial outlay and that I would be better to get another solar panel. We have very strong gusts of wind occasionally, but these are few and far between.
Cheers,
bill
Mar 14th 2007, 7:40 pm
#9
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Joined: Apr 2003
Location: Extremadura
Posts: 1,742
Re: Solar energy vs Mains argument
What an excellent post!
I love the way you've written it, too.
Even a technical twit like me could understand most of it!
O/H will be able to decipher the rest when he gets back from sunning himself in Florida! (Strange that they don't seem to make much use of solar power there??)
We are about to embark on having a house built, and I am keen to make use of solar power.
Your post has given us lots of very useful information to ponder on, so thank you.
Karma to you for "enlightening" a "dim" one!
Regards,
Sam.
I love the way you've written it, too.
Even a technical twit like me could understand most of it!
O/H will be able to decipher the rest when he gets back from sunning himself in Florida! (Strange that they don't seem to make much use of solar power there??)
We are about to embark on having a house built, and I am keen to make use of solar power.
Your post has given us lots of very useful information to ponder on, so thank you.
Karma to you for "enlightening" a "dim" one!
Regards,
Sam.
Mar 14th 2007, 7:43 pm
#10
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Joined: Apr 2003
Location: Extremadura
Posts: 1,742
Re: Solar energy vs Mains argument
PS. Do you use your computer much?
O/H needs his for work, so how is that likely to affect consumption?
He uses the PC a lot (and we've got two of them)!
Thanks.
O/H needs his for work, so how is that likely to affect consumption?
He uses the PC a lot (and we've got two of them)!
Thanks.
Mar 14th 2007, 7:46 pm
#11
Banned
Joined: Feb 2007
Location: Hoping to get away from UK to Spain
Posts: 1,826
Re: Solar energy vs Mains argument
Appologies in advance for the length of this posting, but there are so many different issues with living off-grid.
For anyone that is interested in the Solar energy vs Mains argument - I can't speak for anyone else, I can only explain how my house works and what it costs.
You can buy solar panels for around 3.40Euros per Watt. Lets say you're on a budget and decide to invest in 600W of panels. Immediately you're 2 grand out of pocket.
600 Watts I hear you shout, that won't even run my hairdryer!
Most panels are either 12V or 24V. You don't have to buy 20 12V panels or 10 24V panels to get your 220/240V appliances to work. You can buy just one or two at a time to suit your budget and extend your solar capacity over time as and when the need arises. That's the beauty of small solar systems - you only buy what you need and can afford. The thing to remember is that your house is effectively running off batteries and the solar panels are simply a battery charger. You can include other types of battery charger in your off-grid setup, such as a wind turbine or a petrol/diesel generator.
You can have as few or as many batteries as you like. Obviously the more batteries you have then the more power you can store. But even with one basic car battery you can run a standard tv/dvd, electric lights, anything really. If the battery is fully charged then you should get several hours of watching tv before the power runs out.
Ah but, I hear you cry, a car battery only produces 12V and my tv requires 220/240V, so you're obviously talking rubbish!
Not so, says I. Your car battery is simply connected to a power inverter whch turns 12V into 220/240V. A power inverter can cost as much as you want it to. You can buy a 600W modified sine wave inverter for under £70 from Maplins in England. This will easily run your tv/dvd and lighting.
Batteries are a science unto themselves and car batteries, while being cheap to buy and ok for a few months of use, will not last long and are really a false economy. There are many different types of batteries but the ones designed for solar systems are much better and should last five to ten years at least. We paid about 250Euros for a reasonable 220AH solar battery.
So lets say you buy four solar batteries. That's another grand gone, but you now have about 880 AmpHours worth of storage capacity.
Power inverters are another expense. Yes, that cheap 600W inverter from Maplins will actually go a long way, but what about that 1KW hairdryer you so desperately want to use? Well there are two types of inverter - true sine wave and modified sine wave. True sine wave inverters are better, more efficient and much more expensive. However, search around and you can pick up a new 1500W true sine wave inverter that includes battery charge controller and 50W battery charger from some of the ebay shops for around 750Euros delivered.
So what have we spent so far?
Solar Panels - 2000E
Batteries - 1000E
Inverter - 750E
Total 3750E
But what can I run with this setup?
Well, lets work it out being very simplistic with the figures.
600W of panels for 6 hours direct sunlight produces around 3600W of power per day. That's 3.6KW of power per day going into your batteries.
Lets say you watch about 4 hours tv every night. A modern tv might use around 100W of power, dvd players only use about 15W, so thats about 460W per day.
Buy the energy efficient light bulbs and you use 11W instead of 60W per bulb. Say you run about 4 bulbs at any one time for about 4 hours per night (and that's a heck of a lot more than my family of four use on an evening). That works out at about 180W per day.
So we've used up about 640W out of 3600W so far.
Lets switch that hairdryer on and let the whole family enjoy it for a full hour. Now we're up to 1640W out of 3600W.
What else uses electricity? The iron - big power user, but only when it's in its heating phase. Maybe 1.3KW. Even if you do the ironing for an hour it doesn't actually use that 1.3KW all the time.
The fridge -
The electric fridge is a fairly big consumer of electricity. A typical class A rated fridge/freezer uses about 1kw per day. You could run an electric fridge off this system as well, but it is a big chunk of your available power. But gas fridge/freezers are extremely efficient and almost totally silent. A modern gas fridge looks virtually identical to any electric one. It costs us about 10 Euros per month in gas to run our fridge/freezer.
Looking at these figures it would seem that we've got so much power to spare. However, the observant of you might have realised we only have a 1500W inverter. Plug that iron in while little billy is blow-drying his hair and that inverter is going to squeal. And where does all the ironing come from? We haven't run the washing machine yet!
Washing machines are big power users. No problem if you do a cold wash - only a few hundred watts of power. Try a hot wash and your 1500W inverter may not like it. The solution? get a bigger inverter or switch the backup generator on when you run the washing machine. What backup generator, we hear you ask? The one you bought with the spare 1250Euros from your initial 5000E. Of course, when you run the generator, the batteries also get a very good top-up from the 50W battery charger built into your inverter.
Unfortunately, a good generator is essential because there will always be those times when you get several days in a row of cloud and rain and by the third day your batteries are getting a bit low. Or you have a party and every light in the house is blazing, outside lights are on, stereo blasting out 500W, and you're trying like hell to get your hair blow-dryed in time for the first guests.
The thing about being off-grid is that you become very aware of how much power you are actually consuming. And that's a good thing. You automatically switch off lights when you leave the room. You don't leave the tv/stereo/computer switched on or on standby when you aren't using it. On the negative side, you can't do the ironing when Billy is using the hairdryer. You have to think a little. But at least you don't have to pay a standing charge and then a monthly/quarterly bill on top of that, nor be at the mercy of the electric companies when they decide to upgrade the transformer at the end of the road and cut you off without warning for three days.
5000Euros might seem like a big investment, but solar panels are typically guaranteed for twenty years - they don't go wrong. Batteries have to be replaced maybe every ten years or so. You have to buy petrol or diesel for the genny, but you will probably find that one twenty litre jerry can of diesel lasts for months throughout the summer.
I have neighbours who are desperately waiting for mains electricity to come to our area. They have a generator and nothing else. They spend a fortune on fuel and as soon as the sun goes down they either go to bed or have to switch the genny on. But mention solar to them and they cover their ears and refuse to even think about it. It makes me smile though when at dusk I hear in the distance their generators firing up, and as I switch the lights on and watch a bit of tv powered by my free, clean electricity supply I think about how much I don't have to spend buying more fuel.
For anyone that is interested in the Solar energy vs Mains argument - I can't speak for anyone else, I can only explain how my house works and what it costs.
You can buy solar panels for around 3.40Euros per Watt. Lets say you're on a budget and decide to invest in 600W of panels. Immediately you're 2 grand out of pocket.
600 Watts I hear you shout, that won't even run my hairdryer!
Most panels are either 12V or 24V. You don't have to buy 20 12V panels or 10 24V panels to get your 220/240V appliances to work. You can buy just one or two at a time to suit your budget and extend your solar capacity over time as and when the need arises. That's the beauty of small solar systems - you only buy what you need and can afford. The thing to remember is that your house is effectively running off batteries and the solar panels are simply a battery charger. You can include other types of battery charger in your off-grid setup, such as a wind turbine or a petrol/diesel generator.
You can have as few or as many batteries as you like. Obviously the more batteries you have then the more power you can store. But even with one basic car battery you can run a standard tv/dvd, electric lights, anything really. If the battery is fully charged then you should get several hours of watching tv before the power runs out.
Ah but, I hear you cry, a car battery only produces 12V and my tv requires 220/240V, so you're obviously talking rubbish!
Not so, says I. Your car battery is simply connected to a power inverter whch turns 12V into 220/240V. A power inverter can cost as much as you want it to. You can buy a 600W modified sine wave inverter for under £70 from Maplins in England. This will easily run your tv/dvd and lighting.
Batteries are a science unto themselves and car batteries, while being cheap to buy and ok for a few months of use, will not last long and are really a false economy. There are many different types of batteries but the ones designed for solar systems are much better and should last five to ten years at least. We paid about 250Euros for a reasonable 220AH solar battery.
So lets say you buy four solar batteries. That's another grand gone, but you now have about 880 AmpHours worth of storage capacity.
Power inverters are another expense. Yes, that cheap 600W inverter from Maplins will actually go a long way, but what about that 1KW hairdryer you so desperately want to use? Well there are two types of inverter - true sine wave and modified sine wave. True sine wave inverters are better, more efficient and much more expensive. However, search around and you can pick up a new 1500W true sine wave inverter that includes battery charge controller and 50W battery charger from some of the ebay shops for around 750Euros delivered.
So what have we spent so far?
Solar Panels - 2000E
Batteries - 1000E
Inverter - 750E
Total 3750E
But what can I run with this setup?
Well, lets work it out being very simplistic with the figures.
600W of panels for 6 hours direct sunlight produces around 3600W of power per day. That's 3.6KW of power per day going into your batteries.
Lets say you watch about 4 hours tv every night. A modern tv might use around 100W of power, dvd players only use about 15W, so thats about 460W per day.
Buy the energy efficient light bulbs and you use 11W instead of 60W per bulb. Say you run about 4 bulbs at any one time for about 4 hours per night (and that's a heck of a lot more than my family of four use on an evening). That works out at about 180W per day.
So we've used up about 640W out of 3600W so far.
Lets switch that hairdryer on and let the whole family enjoy it for a full hour. Now we're up to 1640W out of 3600W.
What else uses electricity? The iron - big power user, but only when it's in its heating phase. Maybe 1.3KW. Even if you do the ironing for an hour it doesn't actually use that 1.3KW all the time.
The fridge -
The electric fridge is a fairly big consumer of electricity. A typical class A rated fridge/freezer uses about 1kw per day. You could run an electric fridge off this system as well, but it is a big chunk of your available power. But gas fridge/freezers are extremely efficient and almost totally silent. A modern gas fridge looks virtually identical to any electric one. It costs us about 10 Euros per month in gas to run our fridge/freezer.
Looking at these figures it would seem that we've got so much power to spare. However, the observant of you might have realised we only have a 1500W inverter. Plug that iron in while little billy is blow-drying his hair and that inverter is going to squeal. And where does all the ironing come from? We haven't run the washing machine yet!
Washing machines are big power users. No problem if you do a cold wash - only a few hundred watts of power. Try a hot wash and your 1500W inverter may not like it. The solution? get a bigger inverter or switch the backup generator on when you run the washing machine. What backup generator, we hear you ask? The one you bought with the spare 1250Euros from your initial 5000E. Of course, when you run the generator, the batteries also get a very good top-up from the 50W battery charger built into your inverter.
Unfortunately, a good generator is essential because there will always be those times when you get several days in a row of cloud and rain and by the third day your batteries are getting a bit low. Or you have a party and every light in the house is blazing, outside lights are on, stereo blasting out 500W, and you're trying like hell to get your hair blow-dryed in time for the first guests.
The thing about being off-grid is that you become very aware of how much power you are actually consuming. And that's a good thing. You automatically switch off lights when you leave the room. You don't leave the tv/stereo/computer switched on or on standby when you aren't using it. On the negative side, you can't do the ironing when Billy is using the hairdryer. You have to think a little. But at least you don't have to pay a standing charge and then a monthly/quarterly bill on top of that, nor be at the mercy of the electric companies when they decide to upgrade the transformer at the end of the road and cut you off without warning for three days.
5000Euros might seem like a big investment, but solar panels are typically guaranteed for twenty years - they don't go wrong. Batteries have to be replaced maybe every ten years or so. You have to buy petrol or diesel for the genny, but you will probably find that one twenty litre jerry can of diesel lasts for months throughout the summer.
I have neighbours who are desperately waiting for mains electricity to come to our area. They have a generator and nothing else. They spend a fortune on fuel and as soon as the sun goes down they either go to bed or have to switch the genny on. But mention solar to them and they cover their ears and refuse to even think about it. It makes me smile though when at dusk I hear in the distance their generators firing up, and as I switch the lights on and watch a bit of tv powered by my free, clean electricity supply I think about how much I don't have to spend buying more fuel.
However i notice a few things on this and will point them out so you can clarify that perhaps i have it wrong ?
You put and i qoute "1500W true sine wave inverter that includes battery charge controller and 50W battery charger from some of the ebay shops for around 750Euros delivered" So there the costings you then posted are really only to give output of 1500Watt ??
Now let me explain my household , Normal lighting consists of flashy modern spot lamps ! Which to date i dont think low consumption ones are available ?
The kitchen set of lights alone use some 300 watts .
The hallway set of lights and stairway alone use 300 watts
The kettle uses some 1800 watts
Electric Shower uses 1500 watts
Emersion Heater 2000 watts
Swimming pool pumps pull 2 hp and estimate about 300 watts ?
then i like security outside lights and patio lights est 200 watts
Now i always have the telly on with sattelite system and motorized dish !
Add fridge freezer and washing machine In Hot Summer Air Conditioning .
and on and on it goes !!!!!
1500 watts is pathetic ! May as well just run the house from your car alternator ..
Your 1500 watt which you no doubt sit there and smile at the mrs and say" Look petal that bulbs lit and its free !!" Ahh but is it free and is it such a good move ? When you have established that infact , you have paid minimum 3750 Euros ! And thats without the fitting i presume and the unsightly look of the panels .. Add to that ! all the dodging ie "Hey Petal you cant have a shower today as i am doing the washing and use the candle or you will trip the circuit ! As i am making a cuppa " you get the picture ?
So in my opinion 3750 Euros is a waste of money for solar . If you want power you got to buy a super silent decent proper Diesel generator with a minimum 4000 watts .. You only have 1 lead to connect no battery replacements no working out if you can shower or do the washing etc..
Have proper mains power first choice .. A Diesel generator as back up only .. And dont spend your life living like a caveman in survival mode , if it needs to get to that watch the penny situation . ? well get back to UK and just claim social
Its once again back to what should be a new thread ! Asking why do people buy a villa or house whatever without electricity ? are they mad ? or do they crave the return to the pre war days
ps; Where do you store all them 12v batteries ?
Last edited by Big Pete; Mar 14th 2007 at 7:52 pm. Reason: ps added
Mar 14th 2007, 11:30 pm
#12
Forum Regular
Joined: Feb 2005
Posts: 140
Re: Solar energy vs Mains argument
Hi Pete
Sure, from your stated electricity usage, environmentally friendly alternatives would not suffice, but from my interpretation of Bills post - he wasn't suggesting that everyone should rip out their mains connection and rely on solar?
As for him or anyone else being "mad" to do what they believe in, well I for one disagree, if anyone wants to live in a property without mains electricity, its down to them and just because their lifestyles do not mirror yours does not make them wrong.
I would agree that the cost seems expensive, however as demand increases - the price will fall.
Cheers
Sure, from your stated electricity usage, environmentally friendly alternatives would not suffice, but from my interpretation of Bills post - he wasn't suggesting that everyone should rip out their mains connection and rely on solar?
As for him or anyone else being "mad" to do what they believe in, well I for one disagree, if anyone wants to live in a property without mains electricity, its down to them and just because their lifestyles do not mirror yours does not make them wrong.
I would agree that the cost seems expensive, however as demand increases - the price will fall.
Cheers
Mar 15th 2007, 8:41 am
#13
BE Enthusiast
Thread Starter
Joined: Mar 2006
Posts: 827
Re: Solar energy vs Mains argument
Big Pete,
As always you do throw an amusing angle onto everything. To address some of your points -
"The kitchen set of lights alone use some 300 watts ."
300 watts isn't a lot for a kitchen if you use several 50W halogen bulbs. However, there are direct replacement bulbs available for these fittings that use LEDs instead of halogen bulbs. Instead of 50W they might use 5W.
"The hallway set of lights and stairway alone use 300 watts"
Do you have a dark house? Maybe open the curtains now and again.
"The kettle uses some 1800 watts"
An electric kettle is a ridiculous proposition for an off-grid house. Get a whistling kettle that sits on top of the gas hob.
"Electric Shower uses 1500 watts"
I've never seen an electric shower in Spain and seeing as most houses have a mains connection that provides them with about 4KW of electric then a typical 8-10KW electric shower doesn't stand a chance. Even your "super silent decent proper Diesel generator with a minimum 4000 watts" will run a mile at the thought of an electric shower.
"Emersion Heater 2000 watts "
Emersion heaters are so inefficient I can't imagine anyone using them these days. Even in England most houses have gas fired central heating that heats the water. In Spain you use a gas water heater like everyone else does. Or alternatively use the sun.
"Swimming pool pumps pull 2 hp and estimate about 300 watts ?"
If I could afford a luxury like a swimming pool I would also be able to afford a solar pump for it.
"then i like security outside lights and patio lights est 200 watts
Now i always have the telly on with sattelite system and motorized dish !
Add fridge freezer and washing machine In Hot Summer Air Conditioning .
and on and on it goes !!!!!
1500 watts is pathetic ! May as well just run the house from your car alternator "
Well, maybe you need your own personal power station right next door to your house.
Like I said, when living off-grid you are aware of how much power you consume. I could go on about climate change, global warming, and the rest but that's not the point of this thread. I'll admit that being on mains electric provides you with the convenience of never running out of power (theoretically) but in Spain you still only get about 3.5-4KW per connection. Then you're at the mercy of the electric companies. No doubt every time they put the price up you just accept it and let your monthly direct-debit deduct even more from your bank account.
As for 3750 being expensive, well if it costs 5000€ to get a connection that is just the start. You can easilly spend another 1000€ per year, every year on your electric bill. Add that up over a ten year period and you've spent 15000€. I've spent 3750€ up front, and in ten years time it's still only 3750€.
And as for watching the pennies, I'm still the right side of forty (just) and no way can I afford to retire. I have a full-time job and support my family so I have to watch the pennies.
Maybe you have a nice fat pension to live off? you're lucky you don't have to watch the pennies.
As always you do throw an amusing angle onto everything. To address some of your points -
"The kitchen set of lights alone use some 300 watts ."
300 watts isn't a lot for a kitchen if you use several 50W halogen bulbs. However, there are direct replacement bulbs available for these fittings that use LEDs instead of halogen bulbs. Instead of 50W they might use 5W.
"The hallway set of lights and stairway alone use 300 watts"
Do you have a dark house? Maybe open the curtains now and again.
"The kettle uses some 1800 watts"
An electric kettle is a ridiculous proposition for an off-grid house. Get a whistling kettle that sits on top of the gas hob.
"Electric Shower uses 1500 watts"
I've never seen an electric shower in Spain and seeing as most houses have a mains connection that provides them with about 4KW of electric then a typical 8-10KW electric shower doesn't stand a chance. Even your "super silent decent proper Diesel generator with a minimum 4000 watts" will run a mile at the thought of an electric shower.
"Emersion Heater 2000 watts "
Emersion heaters are so inefficient I can't imagine anyone using them these days. Even in England most houses have gas fired central heating that heats the water. In Spain you use a gas water heater like everyone else does. Or alternatively use the sun.
"Swimming pool pumps pull 2 hp and estimate about 300 watts ?"
If I could afford a luxury like a swimming pool I would also be able to afford a solar pump for it.
"then i like security outside lights and patio lights est 200 watts
Now i always have the telly on with sattelite system and motorized dish !
Add fridge freezer and washing machine In Hot Summer Air Conditioning .
and on and on it goes !!!!!
1500 watts is pathetic ! May as well just run the house from your car alternator "
Well, maybe you need your own personal power station right next door to your house.
Like I said, when living off-grid you are aware of how much power you consume. I could go on about climate change, global warming, and the rest but that's not the point of this thread. I'll admit that being on mains electric provides you with the convenience of never running out of power (theoretically) but in Spain you still only get about 3.5-4KW per connection. Then you're at the mercy of the electric companies. No doubt every time they put the price up you just accept it and let your monthly direct-debit deduct even more from your bank account.
As for 3750 being expensive, well if it costs 5000€ to get a connection that is just the start. You can easilly spend another 1000€ per year, every year on your electric bill. Add that up over a ten year period and you've spent 15000€. I've spent 3750€ up front, and in ten years time it's still only 3750€.
And as for watching the pennies, I'm still the right side of forty (just) and no way can I afford to retire. I have a full-time job and support my family so I have to watch the pennies.
Maybe you have a nice fat pension to live off? you're lucky you don't have to watch the pennies.
Mar 15th 2007, 8:46 am
#14
BE Enthusiast
Thread Starter
Joined: Mar 2006
Posts: 827
Re: Solar energy vs Mains argument
To answer your question...
Yes, I do use the computer a lot - everyday, all day long. My job demands it.
Consumption-wise, I use a laptop. My wife also uses a laptop.
They typically use about 50-60W of power. Compare that with a normal desktop computer which uses 250-300W of power. My Internet connection uses a further 15-20W.
We find that laptops are so efficient that they use an almost insignificant amount of power.
Mar 15th 2007, 8:54 am
#15
Structural Surveyor
Joined: Mar 2006
Location: Sevilla/Cordoba border
Posts: 1,048
Re: Solar energy vs Mains argument
Billgates, a couple of q's - do you have a phone system that uses electricity too? I imagine that being off grid you are also without landline? If so, how much power do you find this consumes?
Do you have satellite TV? If so, does it cope OK being regularly disconnected from the power supply? Thanks!
Do you have satellite TV? If so, does it cope OK being regularly disconnected from the power supply? Thanks!
