If you have a grid connected solar system like I do, you won't be protected from grid interruptions. Your system will shut down during a power failure to protect the safety of linesmen who may be working on the power line and not aware your system is feeding power into it. To protect yourself from power failures, you need batteries which are a whole new can of worms.
I agree that you need an MBA to figure out your expected rate of return. It depends on future power rates, interest rates, etc. I figure in the worse case, I have bought myself insurance against electricity prices spiking through the ceiling even if that event doesn't come to pass. I live in southern california. Only the Mojave desert has better sun and I think only the northeast has higher electric rates.
It doesn't take any brains to install a solar system. You make one phone call, write a big check, and a contractor will do everything. And it is maintainence free.
I'm not sure I'd want to mess with 360 volts of electricity if I can't get a licensed electrician out here. I'm an electrical engineer by profession, so I know what a volt, an amp and a watt is, but I don't deal with more than five volts. I'm pretty sure I could walk around with a multimeter and identify where the break in the circuit is. It worth noting that there are no moving parts, the solar panel output is guaranteed for thirty years and the inverter is guaranteed for ten years. Beyond that there are just wires and circuit breakers like any house would have.
You forgot to mention you were an electrical engineer!
In my opinion though, the important societal impacts will come from both the macro/policy scale and the micro/practical scale and hopefully in the twain shall meet.
I figure it all depends on what you wanna do with your electricity. Without batteries to store the energy you are using the grid for that purpose. What can you power with your solar cells directly? Probably not a computer, or microwave or mostly anything.
You can probably power lights (but during the day O.o?) or heating elements.
Of course I'm using the grid to store energy (well the grid doesn't store energy either but there's like a petawatt on the US grid at any one time). I'm grid connected anyways, batteries are a pain in the rear, and they paid me $3.50 a peak watt to do it. I dump all my power to the grid, run my house off the grid as always, and at the end of the year, me and the electric company will settle accounts.
If you are off grid, you will probably have batteries somewhere in your system. Remote traffic lights are powered by solar. There are solar powered cell phone battery chargers for backpacking and gabbing at the same time. Solar powered water pumps. Your energy reserve can be the gravitational potential energy of the pumped water rather than batteries. If you use solar power to heat a working fluid to run a heat engine, then the hot fluid is your energy storage and it can work all night long.
I just installed a 300v 3KW grid tie system on my garage.
I worked on wiring them to the combiner when it was dark outside, no light no power. I suppose if you had some way to cover them it would work also. It does not take much light to get some voltage, over 1 hour after sunset and it was at 14v.
Aren't there PV system controllers that can handle both a grid connection and battery farm? That's the sort of thing I'd want in a solar energy system.
| The problem will solve itself. | But not in a nice way.
Yes there are. You'll spend a couple thousand more for the system controller and then a couple thousand on the batteries. And figure out where to put the batteries. And btw, the batteries only last a couple of years and then they need replacing. Your call, it depends how often your power goes down.
Battery life for expensive (andf heavy & bulky) nickel iron batteries is decades (perhaps a century under ideal circumstances). Chinese firm using German Varta tooling is only manufacturer that I know.
I would buy the PV now and make contingency plans for batteries.
A simple switch could go from grid connected/no batteries to off grid battery power. Use your IQ instead of the controllers IQ. Monitor over charging (I think Ni-Fe are immune).
Not as such Alan. But they did have some old fashioned pull water out your well with a dutch style windmill.
I was trying to buy something called a sling pump to get micro-hydro from my river here, but I cant find any company that still sells them in the states.
Indeed. For those lucky enough to have land with a year round stream with the required flow and drop, MicroHydro is the gold standard for personal electricity generation. Low cost, low tech, and no batteries needed. For downunder:
Right. So here's my plan. Replace that hard to find hill and stream with a very simple stirling pump driven by biomass/solar. The rest of the microhydro is the same, you now have a biomass hill rather than a dirt/rock one. Your biomass/solar hill can be anywhere.
So, now you have it all. Except a really big hole in the ground which you use for hydo energy storage if you care to do a little digging.
BTW, a thermal machine designed to do nothing but pump water can be very very cheap compared to one made to do harder things like generate electricity.
The world is saved. I can now go down to New Orleans and happily eat myself to death as the gods fated me to do from the beginning.
Note the $38 dinner at the bottom, drink, tax and tip included in these. And the "Top Sixty" Ethnic restaurants (in a city of 250,000) This is the website of our "Talk Radio" food guy. #1 talk show in New Orleans, 2 to 5 PM weekdays,
Hey Eric. By now I would have thought that everybody knows that I MAKE stirling engines. I don't buy them. The ones I want ain't for sale. Have to whittle 'em out with a pocket knife on the back porch.
This one looks like and actually is a piece of pipe. Inside are the usual parts. They rattle around when the thing is heated. You use the rattling pipe to pump water.
A very old idea. Very simple. Very cheap.
And why aren't they being made and sold? Damned if I know. Especially when really crappy and really expensive stirlings are being funded by VC's, apparently the ones with way more bucks than brains.
Hey Eric. By now I would have thought that everybody knows that I MAKE stirling engines.
And many of us lack access to machine tools or even the knowledge of how a cutting tool can work harden metal, how toi hand sharpen a cutting tool, how to work a cutting path, et la.
And why aren't they being made and sold? Damned if I know.
The nitrogen charged, made from pressed sheet metal, 1 hp unit was claimed to exist by http://www.omachron.com back in the last century.
Well a friend told me that would be exactly what I could use on my property here but each time I google 'sling pump' I get advertisements for ladies shoes..
Wind mill driven air lift pump http://www.airliftech.com/
My take is that there needs to be a below the water line tube that extends quite far below the air injection point, so the air will rise up the pipe and not bubble out of the bottom. This has to do with "lift" created pressure. Your sling pump would compensate for this lenght of tube via the internal coil.
You might try a ram pump- google has lots of hits. (and they are noisy)
I was looking to buy a fish farm in Wisconsin 10-12 yrs ago, near Richland Center, and the place for sale worked with 2 hydraulic rams. Low head spring, perhaps 7 ft drop on land. At spring, water went by ram to house and barn, rest of flow and spring to fish raceways. Botttom of raceways had another lg ram for filling stock/gravity watering pond.
Nice place, no electric at all-Amish I believe. Not quite right for fish (raceways dumped into each other, compounding any disease problem). Wonder what happened to it.
I must disagree with the use of this site, it is very uninformative. It gives an energy density in terms of Watts/kg which is inane. Energy density is measured in Joules/Kg, the specific power of the device is watts/kg.
Being in engineering you should know this. Just like I do.
Feel free to disagree with the site. I just posted the link as a primer.
In the real world, 99% of solar houses use lead acid batteries. The rest, nickel-cadmium. Nickel-iron is a hundred year old technology, well known to people who make their living putting up solar houses, and have been found wanting.
Personally, I think all batteries suck. And I don't own a lead mine somewhere.
Looks like you are thinking of carbon fiber flywheels. The energy density of hydrogen ought to include the weight of the tank needed to hold it, but it isn't my chart.
In a home solar situation, you don't care about mass. You buy literally a ton of batteries, stick them in a room somewhere, and they don't go anywhere.
You gotta wish that EEStor was for real: 54 kWh, 400 pounds, $4K. Density's around 0.3, and no worry about the number of times you recharge or the depth of discharge. Typical suburban household today is about 30 kWh per day, so one unit is almost two days worth, three days easily in an energy-efficient household. Don't even have to worry about volumetric efficiency -- for a residential application, it can be as big as a bathtub and it's not a problem.
Imagine the joy of being the house in the neighborhood where the lights are still on, the heat still works, and people are eating hot meals, 24 hours into the blizzard-caused power outage :^)
The specific energy is 55 watt hours per kilogram. Not watts per kilogram. Thanks for pointing that out.
If you overcharge iron nickel batteries, you will electrolyze water into oxygen and hydrogen. The same thing will happen if you overcharge lead acid batteries but nobody is suggesting overcharging lead acid batteries.
Alan
how ya' doing...:-)
you said,
"I would buy the PV now and make contingency plans for batteries."
Or we could find some way to run a PTO (power take off) from our 240D to drive a gen set! :-)
(Don't laugh, I knew a guy who had it set up on a 3/4 ton Ford Diesel once, he had no PV solar, but he had a backup generator when the truck was in the garage!)
Another thought...a small backup generator with a propane (LPG) engine and a propane bottle. Clean, relatively quiet, and LPG will store forever (well, a long time...:-) A couple of power outages, go down and swap the bottle, pretty much like you do on your gas grill....
In fact, I am beginning to think that the ultimate home system, if a person can afford it, might be PV solar, grid tied, an LPG tank (as large as you can afford) buried in the yard, and backup heat and generator running LPG,
Add in the ultimate, a plug hybrid car that runs LPG as the fossil fuel...
hmmmm.....this could be interesting....:-)
Roger Conner Jr.
Remember, we are only one cubic mile from freedom
One issue to consider is the controller. Simple controllers will shut down the system when there is no power coming in. More complex controllers will let the system switch to local power only in the case of a mains failure.
Second, you have to consider batteries. If you only need to worry about a short outage every few years perhaps you could get away with just a very small battery. It might be enough to run the freezer and fridge in the daytime while the solar cells are providing power and have a small battery for some limited lighting or running a radio at night. On the other hand, if you expect the power to be frequently unreliable for days at a time then you'll need to think about sufficient batteries to keep your life going during that time.
I also realised that if a bushfire takes out the mains power the 'smart box' won't let you use the roof current to power a water pump. Hopefully I've solved this problem by rigging up a quick connect pumping system driven by a petrol engine.
In my hacky kind of thinking, I have been wondering if you can fool a grid tied inverter into operation in a power cut by supplying "grid" mains from a 12V battery-powered inverter. You'd have to disconnect from the real grid mains to prevent pushing power back on to the grid and putting maintenance operators at risk.
Beats the crap out of me. Sounds like it will work. Around here your solar system requires a permit, is done to electrical code, and is inspected by the city and the utility before you get permission to turn it on. Nobody doubts that you can get a battery backup to work. We are just arguing about how much trouble it takes.
As a general philosophy, I take a dim view of people who jury rig around safety devices. Some day you'll have the manual switch in the wrong position.
Hi.
If you have a grid connected solar system like I do, you won't be protected from grid interruptions. Your system will shut down during a power failure to protect the safety of linesmen who may be working on the power line and not aware your system is feeding power into it. To protect yourself from power failures, you need batteries which are a whole new can of worms.
I agree that you need an MBA to figure out your expected rate of return. It depends on future power rates, interest rates, etc. I figure in the worse case, I have bought myself insurance against electricity prices spiking through the ceiling even if that event doesn't come to pass. I live in southern california. Only the Mojave desert has better sun and I think only the northeast has higher electric rates.
It doesn't take any brains to install a solar system. You make one phone call, write a big check, and a contractor will do everything. And it is maintainence free.
Could you trouble-shoot it yourself if you couldnt get the maintenance person out?
I'm not sure I'd want to mess with 360 volts of electricity if I can't get a licensed electrician out here. I'm an electrical engineer by profession, so I know what a volt, an amp and a watt is, but I don't deal with more than five volts. I'm pretty sure I could walk around with a multimeter and identify where the break in the circuit is. It worth noting that there are no moving parts, the solar panel output is guaranteed for thirty years and the inverter is guaranteed for ten years. Beyond that there are just wires and circuit breakers like any house would have.
You forgot to mention you were an electrical engineer!
In my opinion though, the important societal impacts will come from both the macro/policy scale and the micro/practical scale and hopefully in the twain shall meet.
I figure it all depends on what you wanna do with your electricity. Without batteries to store the energy you are using the grid for that purpose. What can you power with your solar cells directly? Probably not a computer, or microwave or mostly anything.
You can probably power lights (but during the day O.o?) or heating elements.
Of course I'm using the grid to store energy (well the grid doesn't store energy either but there's like a petawatt on the US grid at any one time). I'm grid connected anyways, batteries are a pain in the rear, and they paid me $3.50 a peak watt to do it. I dump all my power to the grid, run my house off the grid as always, and at the end of the year, me and the electric company will settle accounts.
If you are off grid, you will probably have batteries somewhere in your system. Remote traffic lights are powered by solar. There are solar powered cell phone battery chargers for backpacking and gabbing at the same time. Solar powered water pumps. Your energy reserve can be the gravitational potential energy of the pumped water rather than batteries. If you use solar power to heat a working fluid to run a heat engine, then the hot fluid is your energy storage and it can work all night long.
I just installed a 300v 3KW grid tie system on my garage.
I worked on wiring them to the combiner when it was dark outside, no light no power. I suppose if you had some way to cover them it would work also. It does not take much light to get some voltage, over 1 hour after sunset and it was at 14v.
Aren't there PV system controllers that can handle both a grid connection and battery farm? That's the sort of thing I'd want in a solar energy system.
| The problem will solve itself.
| But not in a nice way.
Yes there are. You'll spend a couple thousand more for the system controller and then a couple thousand on the batteries. And figure out where to put the batteries. And btw, the batteries only last a couple of years and then they need replacing. Your call, it depends how often your power goes down.
Battery life for expensive (andf heavy & bulky) nickel iron batteries is decades (perhaps a century under ideal circumstances). Chinese firm using German Varta tooling is only manufacturer that I know.
I would buy the PV now and make contingency plans for batteries.
A simple switch could go from grid connected/no batteries to off grid battery power. Use your IQ instead of the controllers IQ. Monitor over charging (I think Ni-Fe are immune).
Best Hopes for Renewable Power,
Alan
BTW, were there any microhydro booths ?
Not as such Alan. But they did have some old fashioned pull water out your well with a dutch style windmill.
I was trying to buy something called a sling pump to get micro-hydro from my river here, but I cant find any company that still sells them in the states.
Ever heard of a sling pump?
http://www.riferam.com/
= hydraulic ram ?
I used to live in the same district as this guy and I know the pumps works good
http://www.bamford.com.au/rampump/
The best microhydro designs in the world (IMO) are at
http://www.mhylab.ch
If you would like help in figuring out what to do, let me know.
Best Hopes for more MicroHydro,
Alan
Indeed. For those lucky enough to have land with a year round stream with the required flow and drop, MicroHydro is the gold standard for personal electricity generation. Low cost, low tech, and no batteries needed. For downunder:
http://www.platypuspower.com.au/
Right. So here's my plan. Replace that hard to find hill and stream with a very simple stirling pump driven by biomass/solar. The rest of the microhydro is the same, you now have a biomass hill rather than a dirt/rock one. Your biomass/solar hill can be anywhere.
So, now you have it all. Except a really big hole in the ground which you use for hydo energy storage if you care to do a little digging.
BTW, a thermal machine designed to do nothing but pump water can be very very cheap compared to one made to do harder things like generate electricity.
The world is saved. I can now go down to New Orleans and happily eat myself to death as the gods fated me to do from the beginning.
http://www.arnaudsrestaurant.com/menu.html
http://www.nomenu.com/
Note the $38 dinner at the bottom, drink, tax and tip included in these. And the "Top Sixty" Ethnic restaurants (in a city of 250,000) This is the website of our "Talk Radio" food guy. #1 talk show in New Orleans, 2 to 5 PM weekdays,
http://www.neworleans.com/New_Orleans_Restaurants/
Best Hopes for Fine Dining in New Orleans,
Alan
This reminds me ....
with a very simple stirling pump driven by biomass/solar.
And where are you buying this stirling engine?
Hey Eric. By now I would have thought that everybody knows that I MAKE stirling engines. I don't buy them. The ones I want ain't for sale. Have to whittle 'em out with a pocket knife on the back porch.
This one looks like and actually is a piece of pipe. Inside are the usual parts. They rattle around when the thing is heated. You use the rattling pipe to pump water.
A very old idea. Very simple. Very cheap.
And why aren't they being made and sold? Damned if I know. Especially when really crappy and really expensive stirlings are being funded by VC's, apparently the ones with way more bucks than brains.
Hey Eric. By now I would have thought that everybody knows that I MAKE stirling engines.
And many of us lack access to machine tools or even the knowledge of how a cutting tool can work harden metal, how toi hand sharpen a cutting tool, how to work a cutting path, et la.
And why aren't they being made and sold? Damned if I know.
The nitrogen charged, made from pressed sheet metal, 1 hp unit was claimed to exist by http://www.omachron.com back in the last century.
Nate your sling pump appears to operate the same as an airlift pump. (Air bubble pump).
Looks like it has some advantages. Thanks
D
Well a friend told me that would be exactly what I could use on my property here but each time I google 'sling pump' I get advertisements for ladies shoes..
Helps to click on links
http://www.riferam.com/sling/index.htm
We got our sling pump from Lehman's. They also have
ram pumps,etc.
Nate, air lift pump explained(somewhat)
http://www.maintenanceresources.com/ReferenceLibrary/Pumps/air_lift.htm
Wind mill driven air lift pump
http://www.airliftech.com/
My take is that there needs to be a below the water line tube that extends quite far below the air injection point, so the air will rise up the pipe and not bubble out of the bottom. This has to do with "lift" created pressure. Your sling pump would compensate for this lenght of tube via the internal coil.
You might try a ram pump- google has lots of hits. (and they are noisy)
Nate,
I was looking to buy a fish farm in Wisconsin 10-12 yrs ago, near Richland Center, and the place for sale worked with 2 hydraulic rams. Low head spring, perhaps 7 ft drop on land. At spring, water went by ram to house and barn, rest of flow and spring to fish raceways. Botttom of raceways had another lg ram for filling stock/gravity watering pond.
Nice place, no electric at all-Amish I believe. Not quite right for fish (raceways dumped into each other, compounding any disease problem). Wonder what happened to it.
Nickel costs over $40,000/tonne - gyrated between $43,000 and $51,000 last week. It was only $9,000/tonne in 2000.
I guess that is not a realistic option for the masses.
By the way, the price of Nickel has a strong relationship to war or to expectations of war.
I don't really need a ton of it, just a few pounds in my NiMH or NiFe batteries.
And unlike petroleum, the metal is not irrevocably consumed by the system. It should continue to function for decades at least.
http://www.windsun.com/Batteries/Battery_types.htm
Lot's of battery chemistries each with advantages and disadvantages. My recommendation is not to use batteries unless you are off grid.
A simple switch could go from grid connected/no batteries to off grid battery power.
How do you power your AC appliances from DC batteries? If your inverter down not sense grid power, it will shut down.
I must disagree with the use of this site, it is very uninformative. It gives an energy density in terms of Watts/kg which is inane. Energy density is measured in Joules/Kg, the specific power of the device is watts/kg.
Being in engineering you should know this. Just like I do.
Feel free to disagree with the site. I just posted the link as a primer.
In the real world, 99% of solar houses use lead acid batteries. The rest, nickel-cadmium. Nickel-iron is a hundred year old technology, well known to people who make their living putting up solar houses, and have been found wanting.
Personally, I think all batteries suck. And I don't own a lead mine somewhere.
The cool thing about lead acid batteries is that they give off hydrogen. Collect it and combust! (its not a great deal but every little bit counts)
the uncool thing about lead acid batteries is how much they suck in terms of specific power and energy density.
only flywheels can get close to the energy density of hydrocarbons, and by gross energy flywheels are still a factor of 30 too low.
http://zebu.uoregon.edu/2001/ph162/l8.html
Energy Density of Some Materials (KHW/kg)
* Gasoline ------------------------ 14
* Lead Acid Batteries -------------- 0.04
* Hydrostorage --------------------- 0.3 (per cubic meter)
* Flywheel, Steel ------------------ 0.05
* Flywheel, Carbon Fiber ----------- 0.2
* Flywheel, Fused Silica ----------- 0.9
* Hydrogen ------------------------- 38
* Compress Air --------------------- 2 (per cubic meter)
Looks like you are thinking of carbon fiber flywheels. The energy density of hydrogen ought to include the weight of the tank needed to hold it, but it isn't my chart.
In a home solar situation, you don't care about mass. You buy literally a ton of batteries, stick them in a room somewhere, and they don't go anywhere.
You gotta wish that EEStor was for real: 54 kWh, 400 pounds, $4K. Density's around 0.3, and no worry about the number of times you recharge or the depth of discharge. Typical suburban household today is about 30 kWh per day, so one unit is almost two days worth, three days easily in an energy-efficient household. Don't even have to worry about volumetric efficiency -- for a residential application, it can be as big as a bathtub and it's not a problem.
Imagine the joy of being the house in the neighborhood where the lights are still on, the heat still works, and people are eating hot meals, 24 hours into the blizzard-caused power outage :^)
All that takes is a domestic cogenerator and a battery buffer (assuming you heat with something other than electricity).
Three strange things about that table:
The specific energy is 55 watt hours per kilogram. Not watts per kilogram. Thanks for pointing that out.
If you overcharge iron nickel batteries, you will electrolyze water into oxygen and hydrogen. The same thing will happen if you overcharge lead acid batteries but nobody is suggesting overcharging lead acid batteries.
Alan
how ya' doing...:-)
you said,
"I would buy the PV now and make contingency plans for batteries."
Or we could find some way to run a PTO (power take off) from our 240D to drive a gen set! :-)
(Don't laugh, I knew a guy who had it set up on a 3/4 ton Ford Diesel once, he had no PV solar, but he had a backup generator when the truck was in the garage!)
Another thought...a small backup generator with a propane (LPG) engine and a propane bottle. Clean, relatively quiet, and LPG will store forever (well, a long time...:-) A couple of power outages, go down and swap the bottle, pretty much like you do on your gas grill....
In fact, I am beginning to think that the ultimate home system, if a person can afford it, might be PV solar, grid tied, an LPG tank (as large as you can afford) buried in the yard, and backup heat and generator running LPG,
Add in the ultimate, a plug hybrid car that runs LPG as the fossil fuel...
hmmmm.....this could be interesting....:-)
Roger Conner Jr.
Remember, we are only one cubic mile from freedom
You forgot solar water/space heating (could piggyback off the solar PV) and the ground-source heat pump.
Given what I personally have in the pipeline, we are almost there with that plug-in hybrid being the biggest obstacle at the moment.
For co-gen propane, check out www.marathonengine.com, for co-gen solar, see www.solarwall.com, and for the battery pack, see www.bannerbackup.com. I'm still awaiting the propane co-gen. The other two are on my wish list.
One issue to consider is the controller. Simple controllers will shut down the system when there is no power coming in. More complex controllers will let the system switch to local power only in the case of a mains failure.
Second, you have to consider batteries. If you only need to worry about a short outage every few years perhaps you could get away with just a very small battery. It might be enough to run the freezer and fridge in the daytime while the solar cells are providing power and have a small battery for some limited lighting or running a radio at night. On the other hand, if you expect the power to be frequently unreliable for days at a time then you'll need to think about sufficient batteries to keep your life going during that time.
I also realised that if a bushfire takes out the mains power the 'smart box' won't let you use the roof current to power a water pump. Hopefully I've solved this problem by rigging up a quick connect pumping system driven by a petrol engine.
Hi Robert
In my hacky kind of thinking, I have been wondering if you can fool a grid tied inverter into operation in a power cut by supplying "grid" mains from a 12V battery-powered inverter. You'd have to disconnect from the real grid mains to prevent pushing power back on to the grid and putting maintenance operators at risk.
Carbon Coventry - UK
Hi Carbon,
Beats the crap out of me. Sounds like it will work. Around here your solar system requires a permit, is done to electrical code, and is inspected by the city and the utility before you get permission to turn it on. Nobody doubts that you can get a battery backup to work. We are just arguing about how much trouble it takes.
As a general philosophy, I take a dim view of people who jury rig around safety devices. Some day you'll have the manual switch in the wrong position.
Robert