For those that have successfully gone off-grid, how many watts?

76 Posts
Apr 21, 2008 11:26 am
For those that have successfully gone off-grid, how many watts?

The subject says it all.  If you've take a home or other building that you use regularly (so, not a cabin where you're only there for a few days a month or something), how many watts total solar did it take?  Not talking batteries, other parts, or other costs, but just the solar panel.  How much did it take to take you "off the grid?"

Thanks!

 
Apr 22, 2008 04:22 am
Re: For those that have successfully gone off-grid, how many watts?


If you look at how rural electrification evolved on the grid starting around the early 1900's some of the first residential utility services were only 30 amps at 120 vac. Now you would be pressed to find a new home with nothing less than a 200 amp service at 240 volts.
For me personally I lived for the better part of twenty years without any electricity what so ever and now I live  with a 1000 watt PV array. So what? I don't need them per say I simply wanted them. You could ask 100 people and get a hundred different answers. Bon appetit!
Oh! Thats it inst it, your forming a concensus?
How much wattage do you need/want?
If I may offer a little advice? Try living without electricity for a while and you might realize that you can live without it, or at least a lot less of it.
It could be said that there are four modern day energy essentials in life; cooking, heating, refrigeration, and transportation and all of these with the exception of refrigeration (they perserved) were accomplished by our ancestors for thousands of years before us, without electricity.
 
184 Posts
Apr 22, 2008 09:21 am
Re: For those that have successfully gone off-grid, how many watts?

Travis,

I think it is also important to note those who are not entirely off-grid, but rely on alternatives for a portion of their electrical needs.  I have 425-watts of PV, and I use that to power my refrigerator and freezer.  I've automated my system so that it switches back to grid-supplied power when my batteries get low.  At the present time those devices run for about 12 hours per day on energy from the sun.  I add to the system as my budget allows, and may someday be able to go totally off-grid.

http://solarjohn.blogspot.com

John
 
76 Posts
Apr 22, 2008 10:38 am
Re: For those that have successfully gone off-grid, how many watts?


...If I may offer a little advice? Try living without electricity for a while and you might realize that you can live without it, or at least a lot less of it.
It could be said that there are four modern day energy essentials in life; cooking, heating, refrigeration, and transportation and all of these with the exception of refrigeration (they perserved) were accomplished by our ancestors for thousands of years before us, without electricity.

Oh, I agree!  And yea, just trying to see who else out there has taken a primary dwelling or other significant size building totally off-grid, and just how many watts of PV they're using to do it.

In our master bath, the vanity lights (two sinks, so two sets of four bulbs) are CFLs.  The overhead light is an edison-base LED that draws just 4 watts.  When we're not using the over-sink vanity lights, we just use the LED overhead, and if we want additional light (or warmer light for ambience) I have a pair of wall-mounted oil lamps.  Romantic, and cheap!  Our home also has a fireplace, but we're otherwise all-electric.  I do plan to get more oil lamps, and every bulb in the house is already CFL or LED.  In addition, I have a timer on the water heater that shuts in off from 12-4 AM (when we're sleeping) and 12-4 PM (when we're not home).  The system has to do a little catch-up work at 4am and 4pm, but that's still less energy usage than keeping water hot unnecessarily.  It also heat-shocks sediment off the elements, prolonging their life.  We have a timer on the HVAC that turns the heat down a degree at night, and down to 50° during the day.  When the AC is running, same thing.  Up a degree at night, and up to 80° during the day.  The thermostat has "recovery" mode, so it eases into the new setting slowly.

There are other things we've done, too (reflective tint on a few windows, Energy Star compliant refrigerator, etc.)

We're already doing as much as we can reasonably do, but we're open to further ideas.  Now we're down to seeing what others have done that actually works for them before we do anything big and expensive.

I've already taken my garage off-grid, and am slowly buying the PV necessary to charge my electric truck, which is almost completed.  In the end, the garage will probably have more PV than the house!
 
2 Posts
May 2, 2008 07:04 pm
Re: For those that have successfully gone off-grid, how many watts?



If I may offer a little advice? Try living without electricity for a while and you might realize that you can live without it, or at least a lot less of it.



I know that you can live without electricity, but it is a modern day convenience.  we got away from the Ice boxes, and Coal furnaces long ago.  I am looking for the same answer that this guy was.  I am wanting to know how much power is needed to get my home off of the grid, while still maintaining my current lifestyle. If you take a home with 200A service off of the grid, how many watts is it going to take to get it off?  I tried doing calculations, and came up with 2 different answers.

Using the formula P=IE, with the house having 200A service, and 240V input, P=200A * 240V, you get 48000W or 48Kw.  But the 240V line that comes into the home is split into 2.  giving you 2 lines at 120V with 100A for each run. that would end up P=(100A * 120V)2, which would give you 24000W, or 24Kw.

I could be totally off on my thinking, but which is a more accurate calculation? or would it be a combination of both calculations?

any help would be greatly appreciated.
 
578 Posts
May 2, 2008 07:13 pm
Re: For those that have successfully gone off-grid, how many watts?

still totally off.  attack it from the energy usage, not the available current flow through your service.  go to the learn section, use the loads list and the off grid calculator.  consider getting your hands on home power magazine or getting a copy of this book.  as always, you are welcome to use the forum for advice too Smiley

http://store.altenergystore.com/Books-Classes-Webinars/Solar-Electric-and-Passive-Solar/Photovoltaics-Design-Install-Manual/p481/

james
Alt-E staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 
1 Posts
May 2, 2008 08:00 pm
Re: For those that have successfully gone off-grid, how many watts?

Did you read about the eSolar company that Google is funding?
Here is an idea as a backup, how about a electric generator bicycle?
 
72 Posts
May 2, 2008 08:48 pm
Re: For those that have successfully gone off-grid, how many watts?

Here is an attempt at the whole house off grid needs.

My usage has traditionally run at about 1200kwh per month.

Thats about 40 kwh per day.

To cover this usage, I would need to consider roghly this:

Solar Panels / PV:

an example: 170w panels over 4 net hours of peak performance = 680 watt hours 40000/680 = 59 panels needed!

so, 60 panels at about 800$ each = 48,000$ !!!
Batteries :

an example: 100ah 12v = 1200 watt hours deliverable max at full discharge
To stay in the top 20% ( for longevity and give a couple of days when sun is poor ) = 1200*.2 = 240 watt hours per battery
40000/240 = 167 batteries needed !

so, 168 batteries at 200$ each = 33,000$ !!!
 
....

81k Ouch.

 
2 Posts
May 2, 2008 11:57 pm
Re: For those that have successfully gone off-grid, how many watts?

Thank you,  I knew that the electric companies did meter readings in Kwh, but I guess it never occurred to me that the solar panels were rated the same way. I know last month our usage was about 21Kwh/day. But it is also just getting to spring, and in the summer it will almost double.

Again, thank you, you have given me some things to think about.
 
72 Posts
May 3, 2008 08:37 am
Re: For those that have successfully gone off-grid, how many watts?

I too would love to take my home completely off grid, but due to the high costs of doing that as is ... I'm trying to work it a step at a time. With the goal of getting everything except ( heating, cooling, dryer, oven ) on to RE.

I would love comments and suggestions about what follows:

I'm thinking about and trying to approach it this way:

1. I'm installing a standalone, off grid circuit. ( its not yet complete) That will power my shed, back yard, garage, and two receptacles in my living room ( which doubles as my home office ) This first Array and Bank will provide around 2kwh per day. It might not sound like much, but it meets the needs of this isolated circuit.

- This will give me emergency power when needed, and the opportunity to use some green energy right away ... Reducing my  grid consumption.

2. I'm replacing every light bulb on the property with CFL's where possible and lower wattage elsewhere.

- This reduces my energy needs, and reduces the heat in my home during the summer.


3. I'm replacing my gas powered yard tools with electric versions.

- This reduces my gas consumption,, and carbon foot print. It also gives me a place to put some of the collected solar power ... in to the batteries of the tools. This is not really house-off-grid related, but it is a feel good extra step.

4. Since half the goal of being able to go off grid is to reduce power needs ... I'm looking at;
  a. Solar Hot Water Heating add on
  b. South Side Window utilization;
     i. opening in winter with heat collecting mass added to floor
     11. closing in summer with extra shading
  c. Additional attic ventilation for summer
  d. Pulling solar heated air in to home during winter
  e. Putting hot water heater on timer, to prevent heating while sleeping
  f. Reduce phantom/stand by loads. This one is tough, not sure how to fix this.

- These things help reduce the needs of the RE, and therefore the cost of the system required. So, If you skip the big energy eaters like Heat Pumps and other heating/cooling type of devices ... Your actual energy requirements can drop quite a bit.

5. Add additional PV and possibly Wind Power ... repeat until complete.

Anyways, I would love to hear comments, and also hope this helps and gives Gary some more to think about. I know I'm still trying to wrap my head around a good path to get these things done in an affordable manor.

I guess the question becomes ....

What things can be done to get your energy requirements down ( without changing life style) to where it is affordable to go off grid?
« Last Edit: May 3, 2008 08:59 am by Keith Birchfield »
 
76 Posts
May 5, 2008 11:47 am
Re: For those that have successfully gone off-grid, how many watts?

Here is an attempt at the whole house off grid needs.

My usage has traditionally run at about 1200kwh per month.

Thats about 40 kwh per day.
...
81k Ouch.


Ouch, indeed!  If your home is really using 40kwh / day, there is probably a lot you can tackle before even considering a single solar panel.  Is your home all-electric (as in, HVAC and hot water too)?

 
76 Posts
May 5, 2008 11:50 am
Re: For those that have successfully gone off-grid, how many watts?

I too would love to take my home completely off grid, but due to the high costs of doing that as is ... I'm trying to work it a step at a time. With the goal of getting everything except ( heating, cooling, dryer, oven ) on to RE.

I would love comments and suggestions about what follows:

I'm thinking about and trying to approach it this way:

1. I'm installing a standalone, off grid circuit. ( its not yet complete) That will power my shed, back yard, garage, and two receptacles in my living room ( which doubles as my home office ) This first Array and Bank will provide around 2kwh per day. It might not sound like much, but it meets the needs of this isolated circuit.

I would suggest the shed, garage, etc. (everything NOT the house) be on its own system.  It will always be a smaller system than the house, will still serve as emergency backup power if needed (with an extension cord), and will allow you create a miniature version of what the house would be someday.
Do the house on a seperate system, once you have the garage one completed, and you're happy with it.  By the time your done with the smaller system, you will have a lot more education and ideas that you just can't get any other way.
 
72 Posts
May 5, 2008 01:08 pm
Re: For those that have successfully gone off-grid, how many watts?

... Is your home all-electric (as in, HVAC and hot water too)?

Yes, My home is all electric ... including heat pump, electric heat, hot water heater ... several computers running 24x7 ... large entertainment center with tons of 'phantom load'.

The 1200kwh, is from before I started looking at it, and trying to change my consumption ... with changing life style.

So far, the only thing I've done to improve consumption, is changing (almost) all of my light bulbs.

I definitely need help, and need to learn more about how to reduce consumption ... again, without changing life style.
 
72 Posts
May 5, 2008 01:10 pm
Re: For those that have successfully gone off-grid, how many watts?

I would suggest the shed, garage, etc. (everything NOT the house) be on its own system.  It will always be a smaller system than the house, will still serve as emergency backup power if needed (with an extension cord), and will allow you create a miniature version of what the house would be someday.
Do the house on a seperate system, once you have the garage one completed, and you're happy with it.  By the time your done with the smaller system, you will have a lot more education and ideas that you just can't get any other way.

Thanks for the feedback, it is very much appreciated. I'm sort of doing it that way now. Instead of a drop cord for emergencies.... I'm wiring two receptacles in my living/working space.

And I hear you on the learning by doing comment. I'm learning a lot more by putting hands on, then I could have ever learned by just reading. I've still got a long ways to go though. :-)
 
18 Posts
May 6, 2008 12:06 pm
Re: For those that have successfully gone off-grid, how many watts?

Although I have not gone completely "off grid" I can give you some first steps to get there (because I am getting there).
1-conserve--Replace big appliances first (frig, furnace) my 19' cubic Kenmore frig (freezer top) uses only 1 kilowatt a day.  Furnace is high efficiency (96%).  Replace lights with LEDs (porch light is outside in cold so it is LED) CFL's elsewhere.  I converted 20W desk lamps to auto LEDs (www.ledlight.com).  Add plug strips to phantom loads, then switch all of them off at once (until you need them).  If someone tells you "if it ain't broke don't fix it" but your frig is costing more than $3 bucks a month - its broke.  Oh, get newer shower head (low flow/high pressure) and a new toilet, aerators for faucets.
2-smart solar--start with solar hot water.  This is least expensive and gives the most payback.  You use hot water all the time.  Get solar hot air, there are 4 x 8' panels that only need a 6" vent hole (or 2) to install.
3-solar electric--get this after you review your electric bill (with conserve efforts included).  Most off-griders get a gas generator for the winter season but you can save that cash as you have the grid (use cheapest energy first).
Other savings--wood is a good storage medium for heat, get a wood stove (not fireplace) if you have woods near by.

As for the "how many Watts" question? as much as you can afford.  You may have a family and may use more than just me.
 
1 Posts
May 9, 2008 02:28 pm
Re: For those that have successfully gone off-grid, how many watts?

I want to go off grid. I have 3 acres in central FL and my electricity uses are low by comparison to most homes here. I have had problems finding info on whats needed without having to spend thousands of $. I am even contemplating purchasing my own silicone wafers and attempting to build my own panels, any ideas or am I dreaming?
 
578 Posts
May 9, 2008 06:34 pm
Re: For those that have successfully gone off-grid, how many watts?

making modules from wafers made of silicone will not work out so well. for your first steps do a loads list, figure out your anticipated watt-hours per day of usage, use the free learn section, and get your hands on home power magazine.

http://howto.altenergystore.com/Calculators/Load-Calculator/a74/

www.homepower.com

james
Alt-E staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 
18 Posts
May 12, 2008 11:51 am
Re: For those that have successfully gone off-grid, how many watts?

Depends, if you are going to build a small solar panel to power a 3v, 4.5v, 6v radio then buying individual "cells" will work.  If your going to build panels to power your home "cell by cell" then you are dreaming.  I had the intention (a long time ago) to build a solar panel by buying single solar cells once a week (had $5 allowance).  The 3rd week the store ran out of cells, when the 5th week came there were more cells but they were different (poly crystal instead of mono crystalline).  If your thinking about saving money then buy the panels - you can get 30% back from the government.  Type in "used Solec panels" in your web searcher for a deal on slightly used panels (30% off -not a deduction).
 
3 Posts
May 12, 2008 02:51 pm
Re: For those that have successfully gone off-grid, how many watts?

Buy a kill-a-watt from AE and start taking some readings. Reduce your loading with cf bulbs and LEDS, find your phantom loads and put them on a switchable tract outlet. Batteries are a bigger part than the panels and reserves for the cloudy days are an issue. The easy way is to limit the loads and use what you produce. You can do this with  500 watts, 750, 1000 what ever. It's not an unlimited supply like tapping the grid. For me 1500 watts of panels is the threshold for sunny Colorado for 4000 sq. feet of home. I don't need this much in the summer but I do for the winter. I cover all but the washer and dryer, dishwasher, stove and A/C. High amp and 240 are better handled with the grid tied systems than my 2500AH battery bank.
 
4 Posts
May 12, 2008 03:32 pm
Re: For those that have successfully gone off-grid, how many watts?

My perspective on this is that if your local utility has net metering (power company buys back the excess power you produce), use it! This eliminates the need for expensive batteries since you use the power grid as your storage device. During the day when you are out (and not using much electricity), your PV array is selling its excess energy to the grid. During the times you are at home, any 'excess' energy use that exceeds your PV array capacity is then purchased from the utility grid. An optimum system would zero out (in dollars) what you save with selling excess power and buying needed power. If you over produce, your investment in the PV array is not being recovered since the utility will not pay you enough to justify spending $4/watt on extra panels. If you under produce, you still pay your utility bill but at a reduced cost.
Of course you can still add batteries if you want to go through blackouts (at night!).
Another thing to consider is peak loads. An electric water heater draws 4500 watts when heating (typical). This is why replacing water heating with direct solar is such a deal. The next big thing is the oven which can also use periodic, but large amounts of electricity. Also consider start currents for motors (A/C, refrigerators, etc). Any 'off grid' systems will have to deal with the 'worse case' combinations of these loads (in terms of battery capacity). If you are net metered, the utility supplies you with plenty of power to cover these peak loads.
Being totally independent of the grid has its charm, but requires a lot of thought on smoothing out the loads so as to reduce your investment costs and maintenance costs.
 
3 Posts
May 13, 2008 08:48 pm
Re: For those that have successfully gone off-grid, how many watts?

Bruce all good points. And thats what you do, the grid becomes your battery. I've had 5 black out since going partially off the grid. The neighbors came over asking whats going on? Cost of going into the grid is alot more than you think. Building premit, electrician to sign off the work even if you do it yourself. Disconnects on both sides of the inverter. 2k for the inverter/controller. Plus around here the want it all in a conduit.
 

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