at home energy conservation

“Wood stoves rock. When I get solar heat installed that will rock even more - and my back will thank me.”

“tech, any eperience with wind turbines? I have been reading up on em lately and am weighing costs. A buddy of mine wants to put up a premade kit at his cabin and I am gonna do the install. I found some plans for making one that looks pretty easy, I saw a similar one made on "invention nation" a while back. Its supposed to put out about 1000w.

My other question is the inverter and storage setup. I have about zero experience with that (the standby systems I have worked on have no storagem just transfer switches for gensets etc). Thanks in advance.”

“Personal experience, no. Done tons of reading up on them, and solar PV, solar thermal, etc over the last few years. Some random thoughts below to chew on.

Before you do anything, the first two steps are to cut the loads as much as possible and then estimate the load you need to supply. Might be easy if he's just running a few lights and a TV for a few hours a day. Use a reliable ammeter and figure out his peak useage, and total useage per day. You need to estimate your battery bank and inverter on those numbers, then your charging source on that.

When weighing wind vs. solar PV, in most of the lower 48 they end up being complimentary - its windy when its cloudy and sunny when the wind is calm. Solar requires almost zero maintenance. An occasional quick rinse of the panels to get the dust off. Wind turbines require more intensive maintenance, usually requiring either a climb up the tower or lowering the tower (depending on the type of tower), to replace bearings, check windings, etc, annually. So if that type of maintenance will be an issue at the cabin, solar may be a better option. If he sticks with wind, buy a tower and turbine. There has been lots of research on getting optimum output and homemade rigs just won't get the best output. As for the tower, the key is "go high". Optimally it should be 200 ft. from any obstacles and at least 50 feet higher than them. Probably not possible in a cabin in the woods, so make sure you clear the treetops by a decent margin and factor in tree growth - pine trees especially which can grow a foot a year.

Storage - if you go solar, get a charger that is MPPT (maximum power point tech, I think). If you go wind, sometimes the charger is built into the turbine itself, sometimes you have to get a seperate one designed for wind turbines. Best bet, get a Xantrex 3-stage charger with a remote temperature probe. Cheapest storage for the buck is wet lead-acid but they also need monthly maintenance with distilled water (less often if you also buy special caps that recombine the hydrogen and oxygen that gets off-gassed during charging). AGM (advanced glass mat lead acid) and gel-cel lead acid are more expensive but have advantages. Gel-cel don't need maintenance and can be stored in an unvented space, but need to be carefully charged. One overcharge can kill them since there's no way to add anything back. AGM need maintenance but last longer than wet-filled. AGM and wet lead-acid need vented storage spaces. All batteries should be in insulated boxes designed to hold any liquids should a battery break. Lead-acid batteries of any type shouldn't be discharged below 50% of rated capacity, so you need to buy double capacity based on the daily load.

Inverter - Needs to be able to handle the peak load you calculated. They are most efficient at about 70% of the rated capacity, so if he'll usually run 2 CFLs @ 14W each and a TV at 100W, you probably should get 200 watt inverter assuming he won't need to run a lot more stuff occasionally, or has something with a high starting surge. I always recommend "splurging" for a true sine wave inverter. Some things just don't run on modified sine and some things will fry - quickly. Things like motors, microwave ovens work less efficiently on modified sine. To keep the cabling cheaper, go with an inverter that runs on something higher than 12V, like 48V. Usually a little more expensive than 12V models, but overall system costs should be lower.

Can't think of much else at the moment. A lot of reading, sorry.”

“Really? Why not nicad batts?

thanks for the info. This is interesting stuff.”

“The watts-per-pound for nicads, lithium-ion, and other "newfangled" batteries is much better than lead acid batteries, so they are great for handheld tools or cool new electric cars like the Tesla. But the dollar-per-watt figure is awful. Most of the $100,000 cost of the Tesla is its near-cutting-edge lithium-ion batteries.

You need a good dollar-per-watt figure and could care less about weight for a home system, so lead-acid wins out. It even wins with most electric-conversion cars because the far cheaper cost trumps the large weight penalty. Tesla is going for the high-end market where weight is more important than cost.

Safety and charging are two other issues. The newer technologies can be pretty fickle about getting charged, especially lithium-ion. Overcharge even a little and the battery can be fried. Or explode. There have been several reports of laptops spontaneously burning or exploding because their lithium-ion batteries either overcharged or had a flaw allowing an internal short-circuit discharge (go boom).”

“Ahhh. Thanks for the explanation. Of course the $/watt variable is critical when dropping big coin on a home system and I didn't think about the weight issue.”

“Oh, and when I say "lead acid battery" above, I mean "deep-cycle lead acid battery". Ones listed as deep-cycle at some stores like Wal-Mart aren't truly deep-cycle, they are more of a hybrid between deep cycle and standard. Batteries from companies like Trojan Battery are truly deep-cycle (and as a result are worth the extra cost).”

“Birch, We have a Paloma tankless water heater. We can all 5 take a shower in a row, or at once even. Ours is propane and seems to be reasonable on consumption. You have to be careful though because it's easy to just zone out and you take your time and therefore use too much propane.”

“Agreed, I tend to take longer showers too now.”

“tech,

He has a solar setup with a few (not sure how many) deep cycle cells for charging tools and his TV and radio. All of his lights and appliances are LP, he heats with wood (80 acres of woods). He is looking at wind because his property is on Lake Superior and he has unobstrocted wind for over 300ft of frontage between treelines. Its ideal for a turbine.

Thanks for the headsup on storage cells, how about SLA for wind? We were talking tonite about 12v 24v and 48v, I will steer him to the 48v, its not that much more for the setup. I assume that when he closes the cabin for winter he would need to remove the batteries to prevent freezing? we talked about setting up a heating system ( heat lamps that run off the trubine, storage cell)for them but he doesnt head up there too much after nov except to shovel the roof. Leaning toward removal...

As I said above he has esentially no electric load but would like to cut back on his LP. He will keep his fridge and stove LP but wants to convert lighting and add a few fans (for cooling and heat circulation). He plans on retiring to his cabin in 7-8 years and want to be off grid 100% but still have some flexibility.

Thanks fro all the help.”

“thanks for the brand on you heater strat, i will check it out.”

“Birch:
www.otherpower.com
this is a good site on constructing RE electric systems including how to build windmills.

Wind is rather pricey even in a DIY setup. There is just no way to get around the cost of copper and high powered magnets. If you have a stream then hydro is far more cost effective. PV runs in between the two.

Before you get to deep into it all, you should figure out where you dollars will do the most good. Heating oil and gasoline both run twice as much as my electric bill so there is a lot more potential for savings. I can solar heat, replacing only half of my oil bill and still save more then completely disconnecting from the power grid. Finding a car that can double my gas milage will also produce more profitable results. RE electric has the least potential in my case and would not be worth persuing as a serious project.”

“Hey birch, I bet if you let all those bunnies sleep with you at night, you would stay warm!!”

“i have been fasciated by geothermal exchange heat pumps these last few years. this seems like a perfect solution to me. they cost a lot to put in but the way i do the math the return should come back VERY quickly. look it up in wikipedia or whatever. it's cool. i just can't believe it works. i wish i could find a home that uses this in the winter/summer to see how it really works.

from wikipedia:

The initial cost of installing a Geothermal Heat Pump system is usually quite high and can range from $5,000 to $12,000 for a 2,000 sq. ft. home. However the average cost of most systems is around $20,000. The cost of installation is impacted by the geology of the area, size of the home and location of the home/property. The system can save the average family from $400-$1,400/year, reducing the average heating/cooling costs by 35-70% per household. In many countries, the cost of a system can be mitigated by governmental programs such as tax credits. [1]
last edited: 2/02/08 5:45:33 PM”

“I know a few people that have this system, and they love it! I tried lobbying our school system to install these when they were building the new schools in my community, but the school treasurer is a fascist republican, and the only thing "green" in the buildings are the kids on St. Paddy's Day.”

“birch - sounds like a perfect location for a wind turbine. Sealed lead-acid are what I was calling gel-cell. They work fine, but are more expensive. (Recap from above: "Gel-cel don't need maintenance and can be stored in an unvented space, but need to be carefully charged. One overcharge can kill them since there's no way to add anything back.")

I just looked up the freeze rates for lead-acid batteries, and I found -19F for a 40% charged battery, and -98F for 100% charge. Once frozen, they are trash. If he can be fairly sure that they will stay charged over the winter then he will probably be OK, but he would also need to stick with maintenance-free batteries like gel-cel. But over the winter he should put the wind turbine into a safe mode to prevent damage if there is high wind so charging won't be an option. Also if its out-of-service for 4-5 months a year that cuts down on maintenance. Even if temps weren't an issue, letting the batts stay discharged isn't an option either. They die fast if they are kept discharged. Taking them home to keep them charged/filled might be a big pain but is probably the best option. Design in Anderson disconnects (used in forklifts) for easy removal, and reconnection to an on-grid charging source back at home.

Sounds like his loads are already minimal. Go with CFLs for the new lights and he's set. Make sure a system monitor is designed into the system so he can tell when his batts are getting low. Managing load in an off-grid system is critical. One example: http://www.xantrex.com/web/id/102/p/1/pt/5/product.asp

Hey, I just opened the latest Homepower magazine (issue 122) and the cover story is a review of 24 wind turbines, and it has a thorough article on sizing and setting up a system! Get an online subscription, you can also check out the ads for system monitors and other components.”

“yogi/budda - When my current heat pump and A/C pump need replacement, I'm getting ground-sourced heat pumps. Can't wait.”

“Lumberjack, very good advice on the prioritizing. The project would be far more fun then beneficial for us. Our electric is fairly low already the payback would be absurdly long with batts needing replacement before the payback occurs...

Fuel for my truck is no biggy, its a hog but I only drive 5miles round trip for work.


Tech, thanks for the battery info. I get em fairly cheap through a contract at work, still pricey though. He;d have to haul em out annually, big job for sure. I will try to find the magazine...”

“Magazine: http://www.homepower.com

If you do a system at your own place, why will you need batteries? You only need them for off-grid systems, or ones that will provide some backup in case of a grid outage. Get a grid-tied system and you won't have to buy or maintain batts. You can add backup too, but even then you need far fewer batteries than an off-grid system for several reasons.”

“Tech, I was thinking of storage/backup system.”

“Then go grid-tied w/ a small storage system (500 amps storage @ 12v tops).”

“Does a recliner and a 12 pack qualify as at home energy conservation?”

“Anyone have experience with a tankless water heaters?

I just read a review on one and was surprised at the negatives: http://www0.epinions.com/content_181315997316”

“You have to stay in the home for many many years to have any real savings.”

“hi Sass and Birch..hope all is well..say hi to Tara for me k??

Petey”

“Most of water heating losses are from stand by... a well insulated tank is a much better choice.”

“I wanted to go tankless but ended up putting in a solar water heater that was retro-fitted to my old hot water tank. I loved it. I saved mucho dollars. And that water was HOT HOT HOT!

The reason I couldn't put a tankless in is I couldn't get the extra thick wiring over to where the tank was to be installed.
last edited: 4/06/08 6:51:10 PM”

“I just put in a flapper-less toilet. Most toilets use 1.6 gpf, this one uses 1.28. So far no complaints.”

“Sirpete, HI! We never see her anymore...she moved way, way up north. =(”

“I looked at the cost and passed on them for now until the price comes down. Not so sure it'd be efficient for a family, maybe 1-2 people.”

“Since the cost of fuel will continue to go up, any water heater (or any appliance) that relies on NG, LPG, or oil will become more expensive to operate over time. Install solar now, as Tango has. Electric appliances will have the same problem, except you can install solar PV to negate the rising costs.”

“What solar solutions do you recommend?”

“1. get a solar panel

2. point it at the sun

3. enjoy”

“Should I plug it in somewhere?”

“is it best to go solar now or wait till so many people are going solar/wind that the price for such items comes down to something reasonable?”

“Yes: the sun. Duh.

PS: wear gloves.”

“Until silicon is replaced by thin film materisl like First Solar produces prices will remain high.

Solar thermal will slowly move into the market in few years.
last edited: 4/07/08 11:45:41 AM”