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Is Solar for real? Or am I missing Something?  RSS feed

 
Justus Walker
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Location: Siberia
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I've been watching the cost of solar panels for some years. Finally the recent prices have got me into a mood of contemplation and some serious calculation. But I've been crunching the numbers and it seems that...

I use about 15 kwh a day. If I were doing a 12v system that had 3 days worth of storage and was scaled for optimum battery longevity, completely off the grid, I would need...

About 6000 W worth of panels (4kwh per day per m2 in my area)
About 9000 Ah worth of batteries (15kwh +20% for conversion to and from the battery bank, x 3 days worth of power x 2 to not run the batteries below 50% ever).
About 6 80Ah Contrrollers
About 1 Inverter

Am I missing anything of the main parts??

If this is all about right then...

Solar panels at about $1/W = $6,000
Batteries at about $1.5/Ah = $13,500
MPPT Controllers at about $800 a head = $4,800
Good Inverter about $800?

Total $25,100!!!

Then take this system for say 20 years and break out the replacement cost per day = about $3.43 per day!!
At my current cost of electricity ($0.07) I could buy about 49 kWh electricity per day on just the depreciation of the equipment. Thats more than 3 times the amount it was meant to produce!! Even if my power went up by 3 times i still wouldn't break even in 20 years. only in 30 and that would assume replacing nothing, which is ludicrous!

So, do people who put in solar have to be ideologues? Really far from the grid? Serious civilization collapse preppers?

Please tell me I've got something royally screwed up. I want to do alternative energy. So far the only thing looking good is the horse and the gasifier.

And the TOJAN horse in the whole thing is the batteries!! Right?? Wrong? HELLP me please understand. I'm loosing sleep over this!

 
Burra Maluca
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That's why I'm going for a grid-feed system. They will pay up to €1,700 euros a year for the electricity I sell to them, and pay as normal for what I use, which should be a very small fraction of what they pay me! The system should pay for itself in ten years, and I get a regular income for as long as the panels and the feed-in tariff last.
 
Cj Sloane
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Several issues.

1. 15 Kwh is an incredible amount of energy. There are many things that are not appropriate to run off solar/batteries such as AC (not a problem for you), heat, hot water, stove, large refrigerators/freezers, pumps and probably any appliance 240V.

Cut your usage by 75% before hand and then it's reasonable.

2. Siberia is not a great fit for solar, at least not for half the year. If you're off grid, you need a large battery bank due to how little sun you get. A back up generator would be cheaper than such a large battery bank.

I live in Vermont which has 3 terrible months for solar and I suspect that Siberia is worse. BTW, I've been off grid for 21 years. My energy usage is less than 2Kwh.
 
R Scott
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So, do people who put in solar have to be ideologues? Really far from the grid? Serious civilization collapse preppers?


Or really bad at math.

You wrapped your head around the problem about right. But you forgot a whole lot of little bits and pieces--copper wire and buss bars, fuses, breakers, mounting hardware, etc. All that adds up to a bigger chunk than you expect.

It does not work (today) unless you have a huge grid costs or tax credits to offset the cost.
 
Cj Sloane
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R Scott wrote:
It does not work (today) unless you have a huge grid costs or tax credits to offset the cost.


Or you've minimized your electrical loads...
 
Su Ba
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#1- it would have cost use close to $30,000 to tie into the grid when we purchased our farm. We could have an operational independent solar system for around $20,000. We opted for the solar and thus saved $10,000 the day our system went operational.

#2- We changed our electricity use habits when we went independent solar. Presently we use between 2-3 kwhs daily. We are comfortable at the level of use. We could cutback more but don't need to at this time.
 
R Scott
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Cj Verde wrote:
R Scott wrote:
It does not work (today) unless you have a huge grid costs or tax credits to offset the cost.


Or you've minimized your electrical loads...


Even then, generators are usually cheaper--purely for a dollars/kWh perspective.

The cost has come down dramatically, but it is still not quite there.

Batteries are not sexy. But they are what get you through the night.
 
Marcos Buenijo
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Justus Walker wrote:So, do people who put in solar have to be ideologues? Really far from the grid? Serious civilization collapse preppers?

Please tell me I've got something royally screwed up. I want to do alternative energy. So far the only thing looking good is the horse and the gasifier.

And the TOJAN horse in the whole thing is the batteries!! Right?? Wrong? HELLP me please understand. I'm loosing sleep over this!



I think you're on point (especially the battery comment). If one desires to go off the grid and intends to use electricity, then it seems a battery system is necessary. However, since the electricity is going to be more expensive in this setting any way you slice it, then minimizing usage is required as CJ Verde emphasized. It's been said that the only thing more expensive than off grid electricity is NO electricity. Maybe, but it certainly changes its marginal utility. In other words, most people will find that they don't value many or most of their electrical loads quite so much after a dramatic increase in electricity costs. A combination of energy frugality, not being at the mercy of solar intermittency (meaning a generator is used), and opportunity loading will minimize the battery system - and the battery is the main impediment as you noted. I think solar PV panels are great in the off grid setting, but I say their value is primarily in reducing fuel consumption. I suggest a combination of minimizing electricity consumption and downsizing the battery to provide only 24 hours of storage. Let the generator be the base of the system, and leverage that energy as best you can (use the heat, opportunity loading, efficient running, cheaper fuels, etc.).

NOTE: This all assumes one does not have grid power available. Really, alternative energy doesn't make financial sense when it has to compete with grid power.
 
Cj Sloane
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Burra Maluca wrote:That's why I'm going for a grid-feed system. They will pay up to €1,700 euros a year for the electricity I sell to them, and pay as normal for what I use, which should be a very small fraction of what they pay me! The system should pay for itself in ten years, and I get a regular income for as long as the panels and the feed-in tariff last.


Burra, do you have battery back up?

Nicole Foss has post much over at TAE about how she doesn't think those payments will continue. Are you familiar with her work?

The Receding Horizons of Renewable Energy
 
Burra Maluca
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Cj Verde wrote:Burra, do you have battery back up?


Not really. We had two little solar panels and an old van battery for light and laptop use, with a generator for backup on rainy days. We just timed things so that when the battery was flat we were tucked up in bed.

Then in October we had the mains/grid electric connected and we're in the process of installing big grid-feed solar panels. I think the contract we have guarantees the grid-feed tariff for five years. At the moment it's set so that they pay the same per kw as I would pay them. I'll take my chances after that.

At the moment I have just enough money to pay for the panels. If I'm lucky they will generate an income for life. At worst, I guess I'll end with the solar panels just paying for themselves, but at the end I'll still have the panels. I could play safe I guess and hang on to the money instead, but that would pretty well guarantee that I'll have no income for life, and no solar panels. Sometimes you just have to do what seems right with the chances that you get, and this feels right to me.
 
Justus Walker
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Thanks all for the response!! 15kwh an immense amount of electricity. Hear i'm thinking I'm doing pretty good! I'm down about 50% from the average 1st world consumption!! I heat with wood, cook on gas, heat my water with wood and gas. I try to use energy efficient lights (converting from the CFRs to LEDs currently). And if one doesn't use electricity for pumping (jet pump for getting water to the house, circulating pump to run hot water through the hydronic system) what good is it?

CJ Verde, I'd love to get my consumption down to 2 kWh! How do you do it!! I do have two fridges running (two households living together) and we do use the washing machine but that is it as far as appliances. I don't even own a microwave or a TV!

R Scott, thanks for the input. I just was amazed when i started doing the math. that the battery bank was the killer. Everyone always talks about the cost per watt and here i'm thinking the problem is the cost of Ah. Yes, doing a 24hr system makes way more sense especial;;y if your running a generator that doesn't take money to run (like a gasifier).

Su Ba, for really rural people, or people who have to pull more than about 3,000 ft of wire to get to the grid, I agree 100%! By the way, what is your kWh consumption? Some crazy low number as well??

Too bad they don't sell a Kill a Watt for 220v. I'd love to know what my jet pump, fridge and washing machines actually consume on a day to day month to month basis.

Yah, a 2kw, 24 hr backup system with a generator is much, much , much more affordable. But could i live on 2 kWh hmmmmm......









 
Justus Walker
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Marcos, thanks for that confirmation, especially about the battery part. Just never heard anyone talk about how pig a problem that was, especially with not wanting to cycle them lower than 50% and thus needing to essentially double any required bank size! Crazy!

the answer is various production options I guess, and less storage. Like some solar, some wind (for cloudy rainy days) and a genset running off of a gasifier for everything else.
 
Cj Sloane
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I have a 12 c ft Sunfrost which uses .29 Kwh/day. Compare to a "normal" fridge which is smaller & uses 2x the power. If you have 2 of them, probably bigger than the one I'm comparing to, than thats it!

I do run the pump (120v) when the sun is pumping in good power, but we seem to bath at night so we run the generator for half an hour. It's worth it because that's a big load and really draws down the generator. The pump pumps to a pressurized holding tank.

I'll run the washing machine when it's sunny, but I make sure the pump is off so it doesn't go on at the same time.
 
Marcos Buenijo
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Justus Walker wrote:The answer is various production options I guess, and less storage. Like some solar, some wind (for cloudy rainy days) and a genset running off of a gasifier for everything else.


If you've got no problem in the wood department, then I'm liking a wood gas engine system plus solar in your setting. I think Ken Boak's system is a good basic model for you (http://www.powercubes.com/listers.html).

See also this recent thread: http://www.permies.com/t/32582/energy/Comparing-gassification-steam

 
Marcos Buenijo
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Justus Walker wrote:Just never heard anyone talk about how pig a problem that was, especially with not wanting to cycle them lower than 50% and thus needing to essentially double any required bank size! Crazy!


True that! - there are a lot of assumptions on batteries that get blown up after a little research. Maybe one day there will be cost effective battery storage that solves the problems of existing lead acid batteries, but I'm not holding my breath. Other aspects to lead acid batteries include their very low efficiency when at a high state of charge, and their low efficiency at high discharge rates. Avoiding excessive discharge (i.e. keeping battery state of charge above 50% as is often recommended) pretty much guarantees that the battery system will be at a high state of charge most of the time - exactly where the efficiency is lowest! You see, most people assume that a lead acid battery is 80% efficient, but this assumes a full charge cycle. When charging from about 50% to full charge then the efficiency is more like 60-70%. When taking a battery from about 80% to full, then the efficiency is around 50%. See http://windandsunpower.com/Download/Lead%20Acid%20Battery%20Efficiency.pdf . In my opinion, one of the best ways around this is a combination of minimizing the size of the battery through the strategies discussed previously, and getting serious about opportunity loading. Get a good battery that's relatively small, and don't be scared to let it get discharged once in a while. If the system makes hay while the sun shines, then the low efficiency of the battery won't matter much since the production from the PV array is effectively bypassing the battery. I say a battery should be used for low power loads sustained for extended periods, and/or high power loads only intermittently. Save the serious work for when a generator is online and/or when a PV array is putting out.
 
Sherri Lynn
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There's also somewhere in the middle. For example, solar is so popular right now and a good tax write-off for business, that I was able to pick up 75 used 60 watt panels for $10 each (from a company that installs the new systems and frequently has to remove the old ones). I have also been in contact with a company that does backup power installations and has to remove battieries before their life is up and am expecting a deal on some used batteries. For me, it's all about making the numbers work and achieving a self-sufficiency goal. However, the power panel, combiner boxes etc. cost $4500. I still am expecting putting together a 4.4 kwh system for less than $10,000. Factoring in the importance of self-sufficiency for me, and I would gladly spend my money on this instead of other expensive hobbies like golf, Starbucks, or even a vacation. Add in the tax write-off once I get the system in service and free power for the rest of my life, and it seems like a good investment.
 
Justus Walker
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Sherri Lynn!

The problem is that its not for free for the rest of your life. Say you get a 4.4kw/h system set up for $10,000. Which, all included, is GREAT! But it's not free. Say you battery bank is used, say 60% life gone. Same thing with your panels. so lets say you have got an average of 10 yrs left. You say your panel runs $4500, meaning the rest of the system would run $5,500? (damn good price!) But that $5,500 will be all eaten up in 10 years. so that is $1.5 a day, or 10kwh worth of energy at mean average prices.

I get the idea of rather spending it on this hobbie as opposed to that (especially golf and Starbucks!).

But here is the deal. Self sufficiency is kind of an interesting deal. If i'm getting less power, and having to pay more money (albeit in big chunks separated by many years, but money none the less), how is that self sufficient? Isn't that just cost shifting? Shifting from having to pay every two weeks or every month to having to pay once every ten years?

I want to be self sufficient, too. But it seems to me, that even with the all time low in costs for solar panels, you end up being more dependent on the "grid" than when you were hooked in! The grid of petroleum guzzling highways that deliver, the grid of petroleum guzzling factories that produce, panels and batteries (the main items which will need to be replaced), and inevitably the grid of wealth destroying fiat currency exchange systems (otherwise known as money).

Let me give an example of what I'm talking about. Here, in my area, we HAVE to use hoop houses for things like cucumbers, tomatoes, peppers, etc. We use very small, raised bed hoop houses (the hoop only covers one bed) and the bed is triple dug every year and a good foot to a foot and a half of manure laid in the bottom of the trench to provide heat in the early spring. I ran the numbers on purchasing plastic every 2-3 years, against seeing up a permanent greenhouse with polycarb which should last 10-15 years. We'll say ten just for fun. It comes out just about the same. When I put my polycarb in about a year ago it was barely breaking even above plastic, today it would be a bit cheaper. I don't even take into the consideration the hassle of rolling up the plastic eat year.

So with my new polycarb greenhouse I get more growing space, longer seasons, for about the same amount of money and a lot less work. I'm not kidding myself that the polycarbs solution is "sustainable" or "self sufficient" just better than what I was doing previously.

For me the big deal is daily freedom. If what I am doing is putting a greater financial obligation on me, or I have to use my time in a way id rather not, then that is not a step forward. I really want to be self sufficient. In my example of polycarb greenhouse vs. plastic hoop house, I win. In solar, it seems, unless you don't have any other options, you loose.

However, if i could get 75, 60 watt panels for 4600 bucks, wow! I'd do that in a heart beat!!! Seems like a steal! What kind of a battery bank are you planning. That seems, imho to be the real clincher! But then you might have some freaky awesome deal there as well!!
 
Sherri Lynn
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First of all, the panels themselves totalled $750. It was the other stuff that cost so much. If I took more time to shop, I might have been able to find an inverter, charge controller, battery minder, combiner boxes, etc. at a better deal. However, due to lack of technical knowledge, the prewired box seemed like a good option.

I do understand the cost shifting bit. When I first started considering getting off grid, I thought, "What's the big deal with electricity, they've done without it for thousands of years?" However, my family would rather work than do without electricity, so a compromise was in order. As far as maintenance goes, I understand that the first solar panels they gave a 25 year warranty on because they thought they would last 50, so I'm gambling. When the batteries wear out, I will try for another freaky good deal (and I'm hoping to get one this time). I figure by that time I will have had time to learn about the system, practice using less electricity (you never practice better than when it is a necessity), and I have read about a lot of first timers who have done stupid things and damaged their first battery bank. There are also a lot of new technologies on the market in batteries. If they come out, the old technology may get real cheap. . . . Here's hoping!

Self-sufficiency and freedom mean different things to different people. For me, having my bills so low that even in a low economy if an employer asks me or my spouse to do something that is below our integrity or does not value our time, we can walk without a question, now that's freedom. You see, I believe we were born wanting to be productive, so we will always need to be doing something. I am hoping to do business for ourselves, as that is what the tax law favors, so we can keep more of our money. As far as self-sufficiency goes, I believe we were meant to be a community, whether with other people or a team with nature, so I don't believe any person is an island. For me it's a matter of being able to choose quality over quantity, and you have no idea what goes into something unless you do it yourself. You also have no idea what someone else had to go through to do something unless you have tried it. In some cases, trying to be self-sufficent just helps you value others.
 
Sherri Lynn
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Another plus for electrical self-sufficiency is that I feel that as a society we are being duped, and that leaves a bad taste in my mouth. I personally feel that electric companies are cheering when we stay connected and reduce our energy consumption. Everyone is being legislated in the United States to not use incandescent bulbs for example. What happens when we do that? The power company has to send each person less electricity and that helps them serve more people. They go up on the price per kilowatt, therefore, while your power consumption goes down, your bill doesn't. They don't have to build new facilities or hire more people, they just get a higher profit margin.

On the other hand, if all states decide to give people an extra tax if they have photovoltaic systems like Arizona, they are still winning if it passes. It always seems to be a problem to use systems when they are popular. If you can find another, lesser known, lesser used way to make electricity, you are in a fairly secluded area, and you keep quiet about it, you may find a winning situation. OR if you are able to school yourself to not use it at all. However, there are limits to how much I want to punish myself.
 
Marcus Hoff
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We are just about to sign the deal for our solar panels. I agree, that solar isn't a cheap alternative.
Looking solely at the economic perspective there are some things you are missing in your calculation and some things you can do.
As others already have pointed out, your staring position is important. If you are already off-grid, the cost of getting on-grid can be significant. In our case more then half the price of the solar system. A 1:1 comparison over energy prices is not completely realistic. You tend to save and manage your energy more if your supply is limited. So you need to look at you current monthly bills for comparison instead of the kWh price. I am only familiar with the energy prices here (in Spain) and our electricity bill at current prices would be the same as the replacement cost of the system over it's lifetime. You also need to consider is the that panels and batteries have different lifespans and for batteries this is very dependent on how well you do your electricity management. Finally you need to incorporate the increasing energy prices. Not being able to predict the future myself, I would consider setting the increase at current official inflation rate, about 2%. This is in my opinion a very conservative estimate.
Another point that has been made is your high consumption. Ours (a family of 4) is about half of yours (including electricity for cooking) and is in solar terms considered relatively high. To bring down your energy consumption, I would suggest listing all your consumers in a spreadsheet with their average consumption, then plotting in their usage over a generic 24h period and add up the total. Then you can see, where it makes sense to cut consumption, exchange appliances and so on. Also shifting usage times and turning off consumers at night is easier with the overview of the spreadsheet, this will increase your battery life. If feasible you can add 1-2 small (200-400W) windmills to your setup. This doesn't make economical sense for us, but in other parts of the World it will (check you local weather data, you need wind speeds over 3 m/s, before they even start producing power).
 
Tim Wheaton
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we have a solar system in place that was very simple and is expanding all the time. We started with a plug and play system from goal zero that was awesome. But we quickly out grew it, and for its initial investment was pretty expensive. We now have 4 100w panels on the roof on a fixed frame that feed down to a battery pack of 8 deep cycle farm batteries. The inverter is beside the batteries and with the use of a double male cord we plug it into the wofati outlets and that sends power to all the rooms. It provides 70% of our power needs, but i think another set of panels and batteries will give us a surplus of energy. This summer we hope to have a small fridge and a washer back into the wofati. When we need more energy we run a propane generator that provides 2800w and runs for about 16 hrs on a 20# tank. We can run our meat grinder, vacuum, charge batteries and still have power left over when its running. Mostly is about conservation. We use a series of power strips to plug things into so when we are not using them we turn the power strip off and eliminating the clock/led lights/flashing reminders that are on the electric devices. We heat with wood. We cook with wood. We use about $15 propane a week, and that include some cooking with propane. Next year I don't think we will use $15 propane a month.

prices:

goal zero 90w panels 350w inverter 8 lights $1000
4 100 w panels $600
8 batteries $550
2300w inverter $200
cables/wire/misc $300
generator $450

total spent: $3100

est spending this year for more solar panels and batteries: $1500



 
Sherri Lynn
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What are Wofati outlets?
 
Cj Sloane
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WOFATI is a word Paul made up.
Woodland
Mike Oehler
Freaky-cheap
Annualized Thermal Inertia.
See here for complete info.
 
Walter Jeffries
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The person who owned our land before us spent $45,000 in 1985 to put in grid tied electric. I would rather not have it. Instead for $19,000 I could put in a heck of a hydro-electric system that would generate far more power than we ever use using two generators so that I could take one off line. Or I could put in a heck of a solar electric system for about that much too.

A big key is minimizing your energy consumption.
 
M Foti
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My opinion of solar is that solar is NOT for folks who want to save on their power bill, all it takes is a little bit of research to see that. Solar is for people who cannot get grid power, for people who are "rich" and want to be green, or for people who really are poor and don't use much power. If you want to live like folks did at the turn of the century and still have things like internet, electric light, and a refrigerator, then solar is awesome. When you start needing to run well pumps, water heaters, dryers, washing machines and things like that... not without spending big bucks.

I've been wanting to go solar grid tied for years, never had the cash... now, someone gave me 25 commercial panels 230 watts each... and... the TVA has outlawed grid tied solar in our area. Jerks. So, my fancy free panels are sitting in my shop doing absolutely NOTHING because I don't want to spend the cash on batteries and such to have some dedicated solar circuits in the house... If the TVA gets forced to change their laws, then I'll do a grid tied system to offset our electric bill, but if they do not, I'll just have to save up and get enough batteries and other goodies to maybe run our deep freezer, outdoor wood furnace blower, and maybe our entertainment center off of solar...

 
Brett Andrzejewski
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Justus Walker wrote:

So, do people who put in solar have to be ideologues? Really far from the grid? Serious civilization collapse preppers?

Please tell me I've got something royally screwed up. I want to do alternative energy. So far the only thing looking good is the horse and the gasifier.

And the TOJAN horse in the whole thing is the batteries!! Right?? Wrong? HELLP me please understand. I'm loosing sleep over this!



I think one of the reasons you are loosing sleep is because you are trying to compare industrial electrical power and the major government and industry subsidies TO a small individual who is not subsidized by the government trying to generate power on their own. When we use grid electrical power we do not pay the true cost of the electricity. When you put in a PV system you DO pay the true cost of the electricity.

Now, if you can get state and government subsidies for your PV panels then you can start to compete with subsidized grid electricity. Many states in the US will subsidize PV panels and the government will give you tax breaks. These two subsidies to the individual can make the difference.
 
Cj Sloane
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M Foti wrote: If you want to live like folks did at the turn of the century and still have things like internet, electric light, and a refrigerator, then solar is awesome. When you start needing to run well pumps, water heaters, dryers, washing machines and things like that... not without spending big bucks.


That's me!

I do run a well, 120v, mostly while the generator is on or if I'm getting lots of sun. Washer and propane dryer doesn't use much power really.
 
M Foti
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cj, I was raised off grid (no electricity at all) so I know what it's like! I would have LOVED to have a refrigerator and running water growing up, but we made due! That said, I have a friend who got into a legal dispute with the power company, at the end of it, they removed his power pole and line (actually they were being nice by NOT charging him with a felony for stealing power). Anyhow, he had a small solar setup to run an efficient refrigerator, his computer/internet/entertainment, some led lighting and whatever little things he needed to do. When he wanted a shower he would start the generator and take a shower. He used a very large pressure tank on his well so he could run little bits of water without turning on the genny for things like washing hands, getting a glass of water, etc. Worked out great for him.

Solar CAN be for "poor" people but not without a drastic lifestyle change... Myself growing up without running water and other things like that, I do NOT think I would like going back, although if I had a refrigerator, I'd probably be content.
 
Cj Sloane
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M Foti wrote:He used a very large pressure tank on his well so he could run little bits of water without turning on the genny for things like washing hands, getting a glass of water, etc. Worked out great for him.


Yes, we use a pressure tank too. Last year I went an extra step and put the pump on a timer because we would run the generator to fill up the tank but if someone forgot to cut the breaker to the pump it would turn on when pressure got to low. Now we can't forget to turn it off, only to turn it on.
 
M Foti
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that's a fantastic idea! that way you don't have to run separate circuits for things and worry about overtaxing your batteries/inverter. I love hearing about things like this! I haven't yet decided 100% where all of our panels are going to be utilized, but "rated" watts we have 5750 watts at 24 volts, of course that's "rated" watts AND we haven't acquired any of our electronics yet... but we're on our way and I'm trying to learn all I can in the process.
 
jeff ramage
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if you want to get an evaluation done, contact a distributor of the Dow Solar Shingle system.

They are capable of calculating your loads, required storage, and feedback rate to the grid.

and they will price a complete system for you. that is one data point, then from that you can use their numbers to calculate other options.

http://www.dowpowerhouse.com/

whether or not any of it makes sense for you personally, is a call you'd have to make after having a solid analysis completed.

 
Sherri Lynn
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To M. Foti:

One thing I did not realize when I first started looking into photovoltaic systems is that you multiply your watts in your array times your peak sun hours to find out how much power you could produce in a day. For me, I have 4.5 peak solar hours. With the amount of panels you have, that could produce almost 26 kwh per day. Did you realize that? That's alot of power. You can google a map of solar hours to find what you have where you live.
 
bob golding
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i live off grid quite happily. solar, genny wind turbine, rain water, wood, or oil for heating gas cooking soon to change to wood or oil when i build a stove. most likely wood as i have lost 5 large trees in the last few weeks, all monterey pine so not that good,but free wood is good.

as regards batteries the thing no one has mentioned, although i haven't read all the thread, is the performance going right down the drain in the winter. i get less than half the capacity than in the summer. i have no way of quantifying that of course as i have more solar and less wind in the summer anyway. lights are on longer sit on my butt in front of the fire more, like now. ect. when deciding on how much storage you need remember to take that into account when sizing your bank. i would go afar as to say that is THE most important aspect of designing a system. together of course with reducing your power needs. fridges and freezers are the killers when it comes to power hungry devices. there is a design out there somewhere. think it may be on the back shed site about using a freezer as a fridge. reduces the power by about 90% by only switching on for a short time each day. the most difficult part is not the technology but the change in lifestyle needed. when you have to haul all your drinking water up a muddy field in the rain you value it a lot more and don't waste it.
 
jeff ramage
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if you live where it is colder, you can convert an old refrigerator to a cold box. replace the back panel with a an aluminum plate, and build in out on an exterior cold wall. The aluminum plate is great cold conductor.

And you have to baffle it off for extremely low temps, or your food will freeze solid.

Another way is to use milk jugs and water to create large ice cubes for the fridge and freezer.... fill and set outside to freeze up, and put them in fridge and freezer to keep items cold.

winter is hard on batteries, if your bank of batteries is allowed to get cold, the efficiency goes down. but also the amount of sunshine is of course a lot lower.
 
Chris Olson
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Justus Walker wrote:I use about 15 kwh a day. If I were doing a 12v system


15 kWh/day is not doable on 12V. Go with 24V or 48V and then the cost goes down. Don't pay any attention to folks who say you can't do 15 kWh/day off-grid. We have lived off-grid here for many years and we use one hell of a lot more than that some days. As an example, this is our daily energy consumption to-date for this month (we have an advanced energy logging system). You will notice there is not a single day our consumption has been below 15 kWh and several days above 20 kWh.



Yes, the batteries are expensive but you are designing your system wrong where the batteries are concerned so your proposed "list" is not realistic. Reconfigure your off-grid system for 48V and then areas like needing 4 charge controllers for 12V is reduced to only needing one for 48V for the same capacity. If you get real serious about building an off-grid system then I could spend more time outlining what you need for a 20+ kWh/day system and how much it's going to cost to install it, maintain it and operate it long term.

Typically off-grid power costs around 35-40 cents/kWh. It is not practical to make a move to off-grid when you have utility power available for less than that. The reason those of us live off-grid is because of our location. We are 19 miles from the nearest utility lines and the cost to get utility power here back in 2002 was around $168,000. We liked where we live today and decided to go it on our own. We have never regretted that decision and we have a modern all-electric home (we do not burn a single vapor molecule of propane here, but we do use diesel and gasoline generators) and we do not give up any of the modern conveniences that folks on grid power have. We have wireless Motorola Canopy internet but we have no landline phone service.

We are far enough out in the boonies so that our cell phones only work sometimes when we are on the proper location on our property to get a signal. We heat totally 100% with wood burned in a forced air central furnace and it regularly gets to minus 30-40F here in the winter with 200-240" of snowfall. We do not have any "experimental" or "way-out" stuff - all our equipment is proven, dead reliable off-grid equipment because anything else will break and leave you setting in the dark or without heat. There is no such thing as emergency services here like fire dept or even medical, law enforcement or ambulance service. We are on our own. Most people can't even make it here with a 4-wheel drive truck when the roads are good. There is nobody we can call for help except our off-grid neighbor who lives about 4 miles north of us. And it normally takes them a couple hours to saddle up a couple horses and get here cross-country. Where we live, the wolves and bears are at the top of the food chain and humans are someplace a few links down.

There is nobody that we can call for help. We run our farm here and we enjoy all of it. We enjoy the solitude. We enjoy not hearing cars driving by on the road. We enjoy not hearing or living with the pollution and hustle and bustle of modern civilization. We enjoy spending a good portion of the summer and fall preparing to survive another winter. We have the largest inland sea and largest body of fresh water on earth right out our back door (Lake Superior). We are avid sailors and fisherman (I guess my wife is a sailoress and fisherwoman). It is a package deal that could never be bought living in a developed area.

This is why we live off-grid - we are independent and on our own and we love our location. Too many people try to break everything in life down to dollars and sense. They forget about quality of life.

For us, those solar panels are very, very cheap when we consider what we would have to live with if we lived where most folks live.

 
bob golding
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well said chris. i am not as far off grid as you as the UK is a lot smaller. having said that we are pretty far off off the general hubbub of big cities. our nearest one is around an hour away. as i don't have water electricity or a phone line to live here and joy the comforts of modern technology i have to build and maintain all my own gear. cheap damaged solar panels homebrew windturbine and a chinese genny for back up. if it all stops working i either have to fix it or sit in the dark. makes off grid living that little bit more real than just trying to "save the planet."

i watched a tv program about the winter storms here in the uk at xmas. rather than sit in the dark being miserable one guy got out the summer barbecue and cooked xmas dinner in the garden. bet he will be a bit more aware of how vulnerable he is to power cuts after that.
 
leila hamaya
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1. 15 Kwh is an incredible amount of energy. There are many things that are not appropriate to run off solar/batteries such as AC (not a problem for you), heat, hot water, stove, large refrigerators/freezers, pumps and probably any appliance 240V.

Cut your usage by 75% before hand and then it's reasonable.


^^^^^this. ^^^^
particularly refrigerator.


fridges and freezers are the killers when it comes to power hungry devices. there is a design out there somewhere. think it may be on the back shed site about using a freezer as a fridge. reduces the power by about 90% by only switching on for a short time each day

ah, this is a great idea =) makes sense, and its simple. if you dont open the freezer/fridge very often, it seals up good and tight and have it on a timer, you could probably have an ok fridge on a solar power system, if it was nice and big enough. but its the fridge that is the major power hog, and makes it not work as well.

i've lived with only solar power for years in a system that was set up for a few hundred dollars, buying one good panel and an inverter -getting a number of panels for free because no one knows how to fix them (giving them to my genius geek friend to fix =) which is usually not hard- getting used batteries from the recycling place - taking the volt meter gizmo thingy there even though i dont know what half those settings are i can tell when its still good enough to use =) , which is surprisingly often people throw away batteries with lots of life in them- and buying all those expensive wires and connectors/etc.

now i am not saying that this is the way anyone else would want to go, i did not have very much power to run a fridge/etc, but this could power a stereo, (very low power led) lights, a computer and internet, other odds and ends to be plugged in and rechargable batteries....and even occasionally in summer a blender for a nice smoothie =)

in which case many years of free solar energy was well worth the few hundred dollars and time spent gathering batteries.
 
Cj Sloane
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leila hamaya wrote:

fridges and freezers are the killers when it comes to power hungry devices. there is a design out there somewhere. think it may be on the back shed site about using a freezer as a fridge. reduces the power by about 90% by only switching on for a short time each day

ah, this is a great idea =) makes sense, and its simple. if you dont open the freezer/fridge very often, it seals up good and tight and have it on a timer, you could probably have an ok fridge on a solar power system, if it was nice and big enough. but i


I tried this and was very unhappy with it. It wasn't on a timer though, it was an outlet that had a temperature probe so I cut on & off at specified temps. Purchased thru brewer supply cos.
I really did not enjoy digging through the food to find what I was looking for.
 
r john
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The battery problem may be solved with the latest thermal solar CHP
 
bob golding
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r john wrote:The battery problem may be solved with the latest thermal solar CHP


could you elaborate on that please?
 
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