Solar/wind back up power.....where do I start?

You could start by looking at your electric bill and determine how may kWh of electricity you use per month, per day. You will find that most people who are off-grid are very miserly in their use of electricity. When I see an electric stove, I start to cringe. Also electric hot water heater? Cringing more now.

Then you will want to determine you many kWh of electricity you will need in storage to cover periods when the sun/wind will not supply enough kWh to meet your needs. Obviously, you need storage power for many hours every day, but then also consider periods of no or little sun/wind which could be several days in length or even longer. Storage costs (batteries) are a big expense.

Then you need to size your solar/wind system. PV Watts will help in sizing a solar system for your area. And there are wind tables also available. Generally you would want daily average wind speed around 12 mph or higher. Lower can work, but like night or clouds covering the sun meaning less solar kWh, less wind means less kWh.

There are lots of web based resources available to help you through this maze.

Here are some resources solarpaneltalk.com is similar forum that may be of interest. Homepower magazine is worth subscribing to.

Now the reality, an off the grid power system rarely if ever makes sense to 99% of the population. There is a hefty initial investment and ongoing repeated periodic hefty costs to keep a system running. Most off the grid systems will end up costing around $0.50 to $0.80 cents a KW when the initial and ongoing costs are included. Batteries are quite costly and if you don't treat them right, they will fail prematurely and the cost and hassle to replace them is a big cost. There are higher tech battery's in the press like the Tesla Powerwall that may be less maintenance intensive and longer lasting but the initial cost per KW is 3 or 4 times the cost of flooded led acid batteries so you are committing to extra dollars up front and extra dollars when you need to replace them as there really isn't a option of swapping to a different battery chemistry as the equipment in the system is designed to work with only one battery chemistry unless you get lucky.

You will need to be comfortable with AC and DC power both hands on and calculations. There are folks who will design and supply systems for you if you don't have the skills but inevitably at some point in the future you will need to understand fix and maintain the system. Most folks who depend on someone else end up going on the grid and selling the pieces and parts on craigslist. Expect that you will be running a generator far more often than you will expect as the system will fail at the worst possible time.

You and the others who live with you will have to change your lifestyles. It will revolve around the availability of power especially in the winter. You may get away with normal lifestyle for the first few years but when you kill your batteries prematurely and have to write a big check for a new set, you will change your lifestyle or hook back up to the grid.

It is highly likely I would expect 10 to 1 that you will not be running an off the grid system 5 years after you go off the grid. I used to live in an area of VT that has a lot of former off gridders. The whole concept of "off the gird" was something that back to landers in the area really liked and the electric grid in rural VT is poor and unreliable so remote properties without power makes off the grid a desirable concept. The majority of folks I ran into were ex off gridders, their stories on why they were no longer were off grid started with after the "fill in the blank" disaster we decided that it wasn't worth it. Typical "disasters", losing a major component at the worst possible time and having to redesign the system as the major component was not longer made, having a major electrical fire and burning down the house, losing the batteries in the winter and having to haul fuel for much of the winter to run the generator as they couldn't move the batteries to the house due the their driveway, one spouse deciding that they weren't willing to put up with it and leaving (I ran in more than few divorced folks that attributed the divorce to off the grid issues).

I expect that the prior paragraphs are wasted effort but I give it a try. I would strongly urge you to design a mini system for something like a barn and then live with it for a few year before making the plunge.

Price a Sundanzer refrigerator and freezer (separate units), then look around your current kitchen and figure out how you're going to incorporate two chest style 8cu ft coolers. Following that: look inside your existing refrigerator/freezer and ask yourself and your spouse if you can live with only 8 cu ft of refrigerator and 8 cu ft of freezer space?

If you don't already have one, I suggest you put a "Kill-A-Watt" on your holiday wish list. Once you own one, you'll spend weeks going around your house learning how many appliances you already own are literally thieves stealing power from you day and night, running up your electric bill. Once you put handcuffs on the thieves by putting them on a power strip with a switch (OFF) or simply unplugging them unless you are using them, then you can start getting a handle on how much energy you need in order to live without a grid.

Sundanzer (and Sun Frost) are having a tough time competing with the new EPA energy star fridges on efficiency price and convenience. They made sense long ago when panel were expensive but with cheap AC inverters and panels most off gridders are running energy star standard units. A lot of folks just buy chest freezers and retrofit them with a line voltage thermostat and uses them as fridge. I took a cheap chest type freezer and glued 3" of iso board foam on threes sides and have a removable plug of foam for the top, it cuts the power draw quite a bit. I cannot insulate the back as the coils are imbedded in it. I use it as a freezer but it would work just as well as fridge.

A lot of us have played with a small panel, charge controller and deep-discharge battery.

A few points:
— I find the cheapest panels (per Watt) are on EBay.
— Cheap charge controllers that claim to be MPPT (maximum power tracking) are usually frauds.
— WalMart will recycle dead lead acid batteries for free if you bought them there, or for a nominal fee if you didn't.
— Always put a fuse in line with the battery close to the terminal for short protection.
— Size the panel/battery combo so peak charging rate is at least C/20, IOW a 5A or larger panel is ok for a 100 Ah battery.
— Get a good voltmeter and read about lead acid batteries.

You can def back up some lighting and small electronics for a couple hundred dollars in parts. If you want to run the rest backup, get a cheap genny.

In Germany this system is proving popular for those who have PV panels.

http://www.sonnenbattery.com/sonnenbatterie/technische-informationen/

peakbagger said:

Sundanzer (and Sun Frost) are having a tough time competing with the new EPA energy star fridges on efficiency price and convenience.

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My 16 cf Energy Star freezer used 0.8 kWh per day when I tracked it for a week this summer. Outdoor temps were mostly in the upper 70's to low 80's. One day it hit 90. The uninsulated garage the freezer is located in probably exceed 100 multiple times.

The closest Sunfrost unit (20% bigger) says in 70 degree temperatures, it uses 1.25 kWh per day (56% more).

I hope Sunfrost is just being really conservative about their ratings, but going by their specs, they don't seem to have much going for them other than not requiring an inverter.

iamlucky13 said:

My 16 cf Energy Star freezer used 0.8 kWh per day when I tracked it for a week this summer.

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I have a 15 cf chest freezer I repurposed to a refrigerator with a line voltage thermostat. It sits in the basement, usually fairly cool, and uses via the Kill-o-watt 0.1 kWh/day. Not problem free as humidity condenses into water which needs to be wiped up periodically from the inside of the freezer/fridge.

^^^ LOTS of good info above from jebatty, peakbagger and woodgeek. Ive wanted to play with solar a bit just for fun, but buried in all the info you got above is one key problem:

If you want this just for backup when the grid is down, you will be very disappointed for a very simple reason: When does the grid go down typically? During bad weather. When does solar not perform? During bad weather


That will kill the idea before you even get to the point of sizing it for the really large loads of an all electric house (also a non starter for $$$ reasons).

I must admit, I have a potentially "orphan" array that will be difficult to find a grid tied inverter for when the current one dies, I wired it with all the leads run down to a junction box in my basement so I can easily reconfigure it into a off grid array. I hope that battery technology continues to improve but the reality is I don't lose power often enough and with net metering its just an expensive hobby (like my Unimog).

peakbagger said:

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Now the reality, an off the grid power system rarely if ever makes sense to 99% of the population. There is a hefty initial investment and ongoing repeated periodic hefty costs to keep a system running. ....Most off the grid systems will end up costing around $0.50 to $0.80 cents a KW when the initial and ongoing costs are included. Batteries are quite costly and if you don't treat them right, they will fail prematurely and the cost and hassle to replace them is a big cost. .

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Amen.. could not have said it better myself (from a net negative net metering guy). I've rarely read anything truer than your post .. kudos. It's on the order of simple observations like we live on a planet.

On windmills...The only thing you missed was home sized windmills. I know three people who've raised them and had nothing but headaches and little or no power ( myself and two guys from Vermont)

On off gird... Nearly no one knows how to do off grid right. The best well organized facility I've seen is the Naval base on Catalina Island , just a short hop from san Diego (not the resort island of the same name) . Their solar/battery bank was neat tidy, and well engineered. Tell me , who does not know rugged engineering better than the US navy.( You have to be extra careful when there is the possibility of one or more 165 mm shells landing in the midst of your gadget) The entire battery bank went up in flames at least once in its lifetime

Back to batteries.. Batteries loose capacity in the cold. The simple answer is to keep them warm by bringing them in the house... simple but stupid. Once in the house they can burn it down more easily. That, and you have to be really careful not to drop anything between the terminals. Sounds easy, until you realize to work on the wiring and the connectors, you need a large honking wrench. Once the wrench is in the mix short circuits and fires are possible and likely to follow

peakbagger said:

Sundanzer (and Sun Frost) are having a tough time competing with the new EPA energy star fridges on efficiency price and convenience.....

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The last fridge I bought runs on less than 1 kwh/day.. comparable to the Sun Frosts I used to look at

Which brings up another point.. if you are going to go off grid, the first thing to do is bring down your power demand. I spent a year tracking all the load usage, and figuring out ways to minimize loads (and stay married.. that was the hard part.. the easy solution to sit in the dark with a flashlight and paperback eating gorp from a slop bag does not work if you want to stay married)

I guess the short answer is...

If you have grid power, you're never going to get rid of it. You can't come close to making it cheaper. You couldn't even maintain the batteries if someone GAVE you a system. The cost is just huge.

If your house and appliances was built with having grid power available.. it would be hugely expensive to retrofit.

NOW.. if you had a truly off grid camp, in a location where a grid was impossible. Starting from there... propane refrigeration, small genset, small battery array, solar panels.. You could build you way up to a pretty comfortable off grid situation.

JP

The original post mentioned a well. I'm amazed at the amount of initial draw of my well pump. I'm sure they have soft start motors just for this kind of thing, but I bet it's still a major factor for capacity (not consumption) requirements.

velvetfoot said:

The original post mentioned a well. I'm amazed at the amount of initial draw of my well pump. I'm sure they have soft start motors just for this kind of thing, but I bet it's still a major factor for capacity (not consumption) requirements.

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YUP! My dad had a 6500 watt portable. It was a crappy coleman. He bought a good honda, but a 5000. It kept tripping off.

I told him to go shut the well pump off. He wouldn't believe me. Finally, when he did it.. generator never tripped off again.

Anything that is 220 is a HUGE hit on a generator.

JP

Reverse story with me. I moved to the place, and my 5kw generator wouldn't run the pump. I got a 7.5kw-it can handle it, but you can hear the hit it takes when the pump comes on.

If someone has a three wire well with the run capacitor in a box on the wall, its not that hard to upgrade to a Franklin Variable speed drive, it replaces the run capacitor. It gets rid of any significant pump in rush current. It also does away with a large pressure tank. The way to go on a new well installation.

I have two legs and a ground wire going to the well. No box. That would be a two wire setup?

Oh boy - the OP opened up quite a can 'o worms... Off-grid means truly disconnected from the power grid (some would included water and sewer as well). In suburban areas where there is net metering and people remain hooked into the power grid, solar panels do make a lot of sense, but those folks are not really off-grid. Just like getting off fossil fuels on a national level, getting a single-family home off the grid takes a mutli-disciplinary approach using a variety of alternative fuels, increasing efficiency, decreasing demand, and changing your lifestyle. And off-grid living is certainly a lifestyle of its own.

Deep cycle lead-acid battery banks can be very pricey, especially for very large banks of sealed glass-fiber "maintenance free" batteries. Li ion batteries have higher current density and might be safer but these are very expensive indeed. The batteries need to be monitored closely and kept in a safe, dry, warm space preferably away from the house in case they do catch fire. Home-size wind turbines are just not capable of capturing enough wind to supply that much power due to size limitations, however they can certainly supplement other power sources and they can often make at least some power when solar panels cannot (at night, during bad weather, etc..). If you have the space and the budget putting up several wind turbines could be possible. You would still need a generator for prolonged stormy periods or for when some other aspect of the off-grid system is down. Generators can be purchased that run on multiple fuel types - the tri-fuel units are easily available. I have a 7kW gasoline generator which I modified so that it can run off gasoline, natural gas, or propane from a tank. I normally run it off natural gas, which is quieter and cleaner than gasoline. Diesel generators are also good since they are reliable, can be made very quiet, and diesel fuel is much more stable than gasoline and so a large quantity can be kept in storage on site and will last a long time. Gasoline tends to absorb moisture and cannot be stored for prolonged periods even with storage additives.

I gu

My thoughts:
I have looked at solar panels and wind numerous times and each time it comes to the same conclusion - the numbers just don't work for me. Yes, I have cut back on power usage like many of you but in my case, the decision is to either conserve a bit and live with the hydro bill or cut the cord and go off-grid entirely. The way our system works is that even minimal power consumption is very expensive. When I had just my highway sign lit 4 to 6 hrs. per night on it's own feed and meter, the 'extra padding' that the gov't puts on our hydro bills makes the minimum monthly bill over $50. Each region is different, so keep that in mind. To save $100. per month by investing tens of thousands is not feasible. If I go off-grid, I'll save $150. month and my up-front costs are double.

Yesterday, the hydro guy came by because someone had mistakenly put a new meter on my old highway sign service box that was disconnected many years ago when the cost went nuts. We got into a 10 min. discussion on hydro costs and gov't BS. The interesting part was that he was far more angry than I am. The gov't has screwed things up by handing out hundreds of billions to big multinationals for solar and wind farms and that power is rarely needed but the customers are on the hook for it. The big wind farms (8 thousand of them) are getting .40 Kwh but the average cost of traditional energy is less than .04 Kwh. Ontario produces far more power with the existing nuclear, gas & water generation than we use, yet the gov't keeps financing more wind & solar.

So, yes everyone should try to conserve wherever reasonable but for the average on-grid home, anything beyond that is all about lifestyle, not money.

An interesting read here: http://www.windontario.ca/

NYSB said:

Li ion batteries have higher current density and might be safer

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If you think lithium is safer than lead acid, google "lipo fire"

I use lots of battery technologies in RC applications, and I can tell you in a radio control club Li-Ion batteries are the #1 most common cause of fires and equipment damage. In some ways more dangerous than gasoline.

Bottom line is that all batteries can be hazardous if handled improperly.

velvetfoot said:

I have two legs and a ground wire going to the well. No box. That would be a two wire setup?

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Unfortunately its two wire pump, the start capacitor is down in the hole with the pump.

I am not sure how the Franklin unit works but I think I read somewhere that it sort of turns a single phase pump into a three phase pump using the start winding?

Most newer pump installations have the start capacitor up in a box outside the well as the capacitors tended to fail faster than the pump would. I also have something called a pump protector in my capacitor box that senses if the pump is doing strange things and shuts it down.

IMO, there should be more promotion of, investment in, and utilization of micro hydro.