Solar Power Shed Project
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JimParker
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3RRL said:
You might want to check that warranty... Most battery warranties are pro-rated, so that at 9 1/2 years, you would pay 95% of the replacement cost...
sodamo
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Thanks Rob for a very interesting thread.
We also live completely off grid. Very briefly considered getting commercial power but due to the easements, costs, etc, decided to go solar. We actually have 2 solar PV systems. The first powers the shed we live in, I built base on a Home Power diagram - only 748 watts of PV, 12 golf cart batteries and a Honda 3000si generator. We have lived with it for more than a year. Tommorrow I'm installing a 400 watt AirX wind generator as our part of Hawaii is not all sun-all the time
Our 2nd system is for the main house and so far at $50K is only half your system. Trackers seem to have a poor record here - a real maintenance headache. We installed 36, 125 watt panels (4.5WK) on the tractor/utility shed. Have 12 of the Rolls Surette 4ks25, 1350 ah batteries and Outback controllers and inverters. Our solar contractor feels we can get away not having a big backup generator. We'll have to see. If the wind generator performs as expected for my small system, then that would be my first choice to add to the big system. I really want to avoid the fuel charges
It was really great to stop using the generator to run power tools and just run a big extension cord for the power tools to build the house. Not using much capacity right now, just the tools and a dorm sized fridge to keep drinks cold. The electrician did start rough-in today, so just maybe we'll have some lights in coming months.
Great documentation of your project - thanks
If anyone want to see pics: My Projects
David
We also live completely off grid. Very briefly considered getting commercial power but due to the easements, costs, etc, decided to go solar. We actually have 2 solar PV systems. The first powers the shed we live in, I built base on a Home Power diagram - only 748 watts of PV, 12 golf cart batteries and a Honda 3000si generator. We have lived with it for more than a year. Tommorrow I'm installing a 400 watt AirX wind generator as our part of Hawaii is not all sun-all the time
Our 2nd system is for the main house and so far at $50K is only half your system. Trackers seem to have a poor record here - a real maintenance headache. We installed 36, 125 watt panels (4.5WK) on the tractor/utility shed. Have 12 of the Rolls Surette 4ks25, 1350 ah batteries and Outback controllers and inverters. Our solar contractor feels we can get away not having a big backup generator. We'll have to see. If the wind generator performs as expected for my small system, then that would be my first choice to add to the big system. I really want to avoid the fuel charges
It was really great to stop using the generator to run power tools and just run a big extension cord for the power tools to build the house. Not using much capacity right now, just the tools and a dorm sized fridge to keep drinks cold. The electrician did start rough-in today, so just maybe we'll have some lights in coming months.
Great documentation of your project - thanks
If anyone want to see pics: My Projects
David
patrick_g
Elite Member
Rob, I hope your solar guy is careful what he tells the inspector types as they will probably mindlessly apply it like it came down from Mount Ararat on stone tablets. Not all but many inspectors disengage reason and just go by the book because they often haven't a clue what really matters or WHY something is in the code.
Don't quote me but I think where codes apply there may be prohibitions against running certain combinations of things in a common ditch. Certain separations may apply.
Although the only permit in my whole new house project was registering a leach field I tried to do everything to code or better which was not hard as all the subs were used to working in civilization and new the drill.
You must be as anxious as a kid on Christmas eve waiting to get the system to brew you a cup of coffee and on and on. Every system I ever designed, built, installed or just helped on was the same way for me (all smaller systems.) You'd think my physics background and decades of experience including electronics would have made me pretty immune to getting excited over something like this time and again but NOT SO. Shucks, I'm getting excited over your system and am vicariouusly experiencing the anticipation of seeing the "miracle" of light to electricity yet again.
Pat
Don't quote me but I think where codes apply there may be prohibitions against running certain combinations of things in a common ditch. Certain separations may apply.
Although the only permit in my whole new house project was registering a leach field I tried to do everything to code or better which was not hard as all the subs were used to working in civilization and new the drill.
You must be as anxious as a kid on Christmas eve waiting to get the system to brew you a cup of coffee and on and on. Every system I ever designed, built, installed or just helped on was the same way for me (all smaller systems.) You'd think my physics background and decades of experience including electronics would have made me pretty immune to getting excited over something like this time and again but NOT SO. Shucks, I'm getting excited over your system and am vicariouusly experiencing the anticipation of seeing the "miracle" of light to electricity yet again.
Pat
flusher
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3RRL said:
OP
3RRL
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Jim,
LOL...yeah you're right about that. Hope fully by then they'll have even better batteries to chose from.
Sodamo,
I looked at all your pictures and you've got a great spot on the big Island. You should have posted your project for us. We are also trying to keep the generator run time down to a minimum. That was a key factor in sizing the system. What happened in picture #19 (I think) where your fingers were all bandaged up? Hope you didn't cut them off?
Pat,
I share your anxiousness as you explained. I hear you about those inspectors using common sense too. Hopefully, they'll apply themselves and get a little knowledge on their own.
flusher,
Yes, our home will be kinda large with 2 H/A units. Approx 2,500 sf above, and 900 sf below. Then there's the barn and shop. Our solar contractor sized the system for us after we told him what our usage would be, and that's what he came up with. He sat down with us and made a list of everything electrical we will use and how much per year. We feel very good about his services so far.
Thanks for looking,
LOL...yeah you're right about that. Hope fully by then they'll have even better batteries to chose from.
Sodamo,
I looked at all your pictures and you've got a great spot on the big Island. You should have posted your project for us. We are also trying to keep the generator run time down to a minimum. That was a key factor in sizing the system. What happened in picture #19 (I think) where your fingers were all bandaged up? Hope you didn't cut them off?
Pat,
I share your anxiousness as you explained. I hear you about those inspectors using common sense too. Hopefully, they'll apply themselves and get a little knowledge on their own.
flusher,
Yes, our home will be kinda large with 2 H/A units. Approx 2,500 sf above, and 900 sf below. Then there's the barn and shop. Our solar contractor sized the system for us after we told him what our usage would be, and that's what he came up with. He sat down with us and made a list of everything electrical we will use and how much per year. We feel very good about his services so far.
Thanks for looking,
patrick_g
Elite Member
Although the top dude at "Home Power" is counter culture, retread hippy, left wing way past Marx he is still a smart guy and has built quite a magazine with impressive credentials. He may have had a legal and or liability issue that could have bordered on conspiracy depending on how he interfaced with the illegal perpetrators.
I liked that section too and felt it depicted what was, at worst, a victimless crime. Still, if he were jeopardizing the magazine, dropping that section was prudent. I'm not sure all the utilities are so enlightened as to use net metering.
Many still buy from you at wholesale and sell to you at retail. Some don't want to be involved and place many restrictive barriers in your path.
Pat
I liked that section too and felt it depicted what was, at worst, a victimless crime. Still, if he were jeopardizing the magazine, dropping that section was prudent. I'm not sure all the utilities are so enlightened as to use net metering.
Many still buy from you at wholesale and sell to you at retail. Some don't want to be involved and place many restrictive barriers in your path.
Pat
patrick_g
Elite Member
3RRL said:
Read and reread parts... I wish I were close enough to be of actual physical help. I'm still like a kid with an errector set and science hobby 10 in 1 kit when it comes to playing with solar installations and such.
Are you going propane with solar preheat or what for DHW? (I have slept since the earliest part of this thread)
The glass vacuum bottle collectors are worth looking into for hot water.
Pat
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3RRL
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Pat,
Are you going propane with solar preheat or what for DHW?
Propane for sure but we are not sure exactly how to do the solar preheat? My wife will be in charge of this part.
The glass vacuum bottle collectors are worth looking into for hot water.
Pat, we are not familiar with this concept but any information would be great. How would this work? Is it part of the solar preheat you mention above? We are having radiant heat in our lower floor and maybe that would be a good application for a closed system? Again, we are NOT up on how those systems work but when the benefits were explained, we liked the idea and decided that's what we wanted.
Thanks,
Are you going propane with solar preheat or what for DHW?
Propane for sure but we are not sure exactly how to do the solar preheat? My wife will be in charge of this part.
The glass vacuum bottle collectors are worth looking into for hot water.
Pat, we are not familiar with this concept but any information would be great. How would this work? Is it part of the solar preheat you mention above? We are having radiant heat in our lower floor and maybe that would be a good application for a closed system? Again, we are NOT up on how those systems work but when the benefits were explained, we liked the idea and decided that's what we wanted.
Thanks,
patrick_g
Elite Member
3RRL, DHW from solar collectors are fairly well understood but unfortunatley there are a lot more people and outfits doing the work than realy understanding it. In most solar DHW applications there is at least some back up heat like a standard tank type water heater. There are two main system types: 1. potable water goes through the collector (might need softening to prevent mineralization) and 2. (more popular where freezing is a hazard) an anti-freeze solution circulates through the collection system and a heat exchanger or else a water heater with desuperheater coil.
You can even lay out a thermosyphon system if you have the vertical elevation to support it. In this latter system you don't need a pump to circulate the fluid in the collection system. This has extra appeal for some solar only folks because it saves the electrical load of the pump. In this system the collectors are located well below the elevation of the storage tank (usually a pretty standard DHW heater tank.) The solar heated water is expanded and less dense than the coldest water in the water heater (or desuper heater coil or....) So the cold dense water subsides and displaces the hot water forcing it up to the water heater tank. The cold water falls down to the collectors where it is heated and the cycle continues as long as the water in the solar collector is hotter than the coldest water in the water heater (collects at the bottom.)
You have to have a back flow preventer (check valve) to prevent the system from being a water cooler when there is insufficient water heating capability in the collector, like at night and other not so super solar periods.
The thermosyphon system has to engineered carefully to ensure low enough restriction to flow since you don't have a pump. They can be made to perform well but not every installer or even designer is a prime candidate for success. Lots of installers would just let you USE A PUMP instead of them using their head.
If you have a freeze danger (air temp doesn't have to go to or below freezing to get freezing conditions.) Good absorbtion of solar energy usually goes with good radiative properties as well (reciprocity.) if you expect temps to get in the 35-38F region for a fair period during clear skies then you should consider the anti-freeze in the collector version.
The thermos bottle type collectors I mentioned...
Thermos bottles are also called vacuum bottles. The vacuum layer elliminates convective losses as there is no medium for convection. In solar collectors the sun shines through the clear glass of the evacuated bottle and is absorbed by the contained absorber (high efficiency, absorbs most of the energy) through which passes the water to be heated. There is little conduction as the design of the bottle minimizes the path for heat flow from the inner layer to the outer layer (remember the thermos bottle, inner glass layer and outer glass layer touching only at the top where the cork went. Some of these have aluminized inner layers on one side so that light that misses the collector is reflected back to the collector.
These solar thermos bottles cost more by the pound than lower tech approaches but can outperform many alternatives and don't need to cover as much area since they are more efficient. I suppose a minor factor is less total roof load for equivalent performance.
If the glass blower did a good job there is no particular limit to the life of one of these collectors. I suppose a kid with a BB gun could give you a bad day or a violent thunderstorm with big hail stones. This is a danger to most solar collectors used for DHW. I have heard of protective mesh being used to exclude large hail (works for Sola tube type products too.) By the way Sola tube type illuminators should be a consideration to reduce interioir lighting loads during the day.
I did a GOOGLE on "thermos bottle solar collector." There apparently is a lot more info available now than when I studied these about 10 years ago. There were oodles of hits.
Just curious but did you put a pencil to the tradeoff between the tracking mounts and buying more panels? Times were when a single axis tracker that you manually adjust the other axis (super simple job a few times a year) was a $ saver.
Pat
You can even lay out a thermosyphon system if you have the vertical elevation to support it. In this latter system you don't need a pump to circulate the fluid in the collection system. This has extra appeal for some solar only folks because it saves the electrical load of the pump. In this system the collectors are located well below the elevation of the storage tank (usually a pretty standard DHW heater tank.) The solar heated water is expanded and less dense than the coldest water in the water heater (or desuper heater coil or....) So the cold dense water subsides and displaces the hot water forcing it up to the water heater tank. The cold water falls down to the collectors where it is heated and the cycle continues as long as the water in the solar collector is hotter than the coldest water in the water heater (collects at the bottom.)
You have to have a back flow preventer (check valve) to prevent the system from being a water cooler when there is insufficient water heating capability in the collector, like at night and other not so super solar periods.
The thermosyphon system has to engineered carefully to ensure low enough restriction to flow since you don't have a pump. They can be made to perform well but not every installer or even designer is a prime candidate for success. Lots of installers would just let you USE A PUMP instead of them using their head.
If you have a freeze danger (air temp doesn't have to go to or below freezing to get freezing conditions.) Good absorbtion of solar energy usually goes with good radiative properties as well (reciprocity.) if you expect temps to get in the 35-38F region for a fair period during clear skies then you should consider the anti-freeze in the collector version.
The thermos bottle type collectors I mentioned...
Thermos bottles are also called vacuum bottles. The vacuum layer elliminates convective losses as there is no medium for convection. In solar collectors the sun shines through the clear glass of the evacuated bottle and is absorbed by the contained absorber (high efficiency, absorbs most of the energy) through which passes the water to be heated. There is little conduction as the design of the bottle minimizes the path for heat flow from the inner layer to the outer layer (remember the thermos bottle, inner glass layer and outer glass layer touching only at the top where the cork went. Some of these have aluminized inner layers on one side so that light that misses the collector is reflected back to the collector.
These solar thermos bottles cost more by the pound than lower tech approaches but can outperform many alternatives and don't need to cover as much area since they are more efficient. I suppose a minor factor is less total roof load for equivalent performance.
If the glass blower did a good job there is no particular limit to the life of one of these collectors. I suppose a kid with a BB gun could give you a bad day or a violent thunderstorm with big hail stones. This is a danger to most solar collectors used for DHW. I have heard of protective mesh being used to exclude large hail (works for Sola tube type products too.) By the way Sola tube type illuminators should be a consideration to reduce interioir lighting loads during the day.
I did a GOOGLE on "thermos bottle solar collector." There apparently is a lot more info available now than when I studied these about 10 years ago. There were oodles of hits.
Just curious but did you put a pencil to the tradeoff between the tracking mounts and buying more panels? Times were when a single axis tracker that you manually adjust the other axis (super simple job a few times a year) was a $ saver.
Pat
