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Can solar be used as back up power instead of a generator?  RSS feed

 
Theresa Brennan
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We are looking into getting a generator for backup power and the stationary ones I'm looking at are around $2-3,000 dollars. So I'm just wondering if it is possible/practical to use solar power as a backup instead? Totally new to this and just asking the beginner questions
Thanks.
Theresa
 
allen lumley
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Theresa Brennan : This is a very good Question, unfortunately the answer is it depends, if all we are talking about is the amount of Grid supplied Kilowatts that must be
re-supplied from some where else then you just need to look at your utility bills and figure how much you can shave off of that !

Location, Location, Location! Which is more costly, or likely to be more costly your heating season, or your cooling season ? This makes a big difference in how
useful any advice is !

Remember that moving off grid will mean that you will need to provide a source of power to pump water from a distant well, and that pump will cycle on and off
every time you turn on a faucet - Two things that mark the boundary between third world living and 2nd world is water in the kitchen (only) and a Washing machine
- Believe me, that was a big deal for your Great-Grandmothers!

Propane can work as a substitute for CooKing, and supplement heat, are you willing to just heat the core of your house and snuggle up to a mound of blankets for
most of a heating season? Only you can decide how many Kilowatts you have to have, and find out what substitutions you are willing to live with.

Google "Green home Tours'' And visit these people and make friends and take lots of notes, mostly - '' I'll never do that again "" or '' If i had the chance to do THIS
over again'' ! - - -

Invest in a ''Kill-o-watt'' measuring device, to determine the cost for ruNning each appliance in your house, work through all of them to find out Daily and Weekly/
monthly totals and then look at your utility bills, they should tell you what the average person in your neighbor hood uses to allow you to compare yourself to them!

a 2-3,000 dollar generator is pretty good for when your local grid goes down during a storm, trying to use it for supplementing power needs will cause most
Generators in that price range to fail within a year, Think 4,-5,000 and get a propane powered one that burns much cleaner and will last much longer !

I am sorry this is not up-beat, but anyone who tries to help you determine what is right for you must live with you and climb into your head, . . . Be the person you
need/want to be ! For the good of the Craft ! Big AL !
 
Michael Cox
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It also very much depends on if you are looking for an emergency back up (for when mains supply goes down) or to take yourself totally off grid. They are very different setups.

Emergency backup needs to run lights, some essential appliances (fridge/freezer?) for a few days while power is restored. For a short period in an emergency you can economise on power consumption (turn off air-con, cook with bottled gas rather than electric, have a few essential low energy lights on around the place).

Going off grid permanently needs totally different considerations - long term reliability comes into, so cheap generators probably won't cut it. Solar systems seem reliable in terms of component life times, but are weather dependent.
 
Theresa Brennan
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Thank you for both of the replies. I should have been more specific about what I meant. While I would like to be off-grid someday, right now we are just trying to find a backup power source and I wondered if there is any way we could get a small solar system that would be enough for short term power outages. My guess is that it is not practical but you never know until you ask people who really know

Theresa
 
Michael Cox
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If you have a solar setup it makes sense to use it full time (the fuel costs nothing after all), so you are very unlikely to find setups which are only there as emergency backup. You can get "grid tied" systems which feed energy back to the grid when not being needed in the house. When the grid goes down for some reason they can keep the house supplied.
 
Theresa Brennan
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Thanks Michael. That makes sense and answered my question. I appreciate the help!
 
Marcos Buenijo
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Michael Cox wrote:You can get "grid tied" systems which feed energy back to the grid when not being needed in the house. When the grid goes down for some reason they can keep the house supplied.


A grid-tied solar PV system can be configured to provide electricity during a loss of power, but the vast majority of systems do not provide this feature. Let me be clear: the majority of homes that have installed PV arrays are grid-tie systems. During a power outage (loss of grid power) the vast majority of these systems are completely useless for providing electricity. http://www.wholesalesolar.com/AC-coupling.html

Note that there are new inverters on the market that can allow a grid tied solar system to provide electricity to the home at a limited rate during a loss of grid power. http://www2.buildinggreen.com/blogs/beating-achilles-heel-grid-tied-solar-electric-systems . However, a battery system is required for powering substantial loads during a loss of grid power.
 
Chris Olson
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Theresa Brennan wrote:We are looking into getting a generator for backup power and the stationary ones I'm looking at are around $2-3,000 dollars. So I'm just wondering if it is possible/practical to use solar power as a backup instead? Totally new to this and just asking the beginner questions
Thanks.
Theresa


Theresa, I would recommend the generator instead of solar panels. The generator will be cheaper and much more reliable. The solar panels require a substantial investment in other equipment to be able to use them. The generator is a relatively simple install by comparison. It would take roughly $20,000 worth of solar panels and associated equipment to match the capabilities of even a small standby generator that costs less than $2,000.
 
Theresa Brennan
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Thanks Chris. Appreciate the help.
 
Chris Olson
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Theresa Brennan wrote:Thanks Chris. Appreciate the help.


You're welcome - I'm keeping in the mind the one post where you said you'd like to be off-grid someday. When and if you make that move you will still need a generator. So buying one is not a bad investment anyway, and it's much more practical for standby power than a solar battery-based standby power system. Batteries are quite expensive, and they go bad if they're not used so your investment ends up being wasted for now. When you go off-grid where you will be using your batteries every day, then the investment in them (and in the solar) makes more sense.
 
Theresa Brennan
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Good thoughts. Thanks again Chris. I have been looking at Honda generators (EM6500). Do you think it is worth the extra money for one? What about the surges or whatever it is called that affects sensitive things like electronics? I am trying to find one used but they are still considerably more.

Theresa
 
Chris Olson
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Theresa Brennan wrote:Good thoughts. Thanks again Chris. I have been looking at Honda generators (EM6500). Do you think it is worth the extra money for one?


The Honda's are definitely worth the extra money. We have a Honda EM4000SX here for peak load support. The EM6500SX will make an excellent standby unit for a home with utility power. The Honda EM-SX series generators put out utility grade power. They have an electronically controlled iGX engine that communicates with the load computer in the generator. They will maintain PERFECT 240V 60Hz power even at 125% of their continuous rating for 20 seconds.

You would not be happy with a Generac or any of the cheaper stationary units because unlike the Honda, they are only rated for 50% of their nameplate output capacity continuous. So it takes a 12 kW Generac Guardian series to match what a Honda EM6500SX can do on standby, although the Generac will have more surge capability. But the Honda will do it on a little less than 1/2 the fuel that the Generac burns.

There is one thing about Honda generators - you will never find anyone who has bought one that is unhappy with it.
 
Theresa Brennan
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Glad I asked. Thanks again
 
Markus Loeffler
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Theresa,

Gas generators are certainly a reliable option but I dislike the fact that they burn gasoline and produce stinky CO2.
If you just want to have backup power for a few appliances you can do this by spending less than $2000 on a few solar panels and some batteries. I installed a system at my house after I had a 4 day black-out (Pasadena, DEC 2011). My small off-grid system is producing 2kWh per day. I ran a separate circuit (just a long power strip) at my house powering the fridge, TV, stereo, internet, laptop/phone chargers. At night it automatically switches to the city grid to save battery life.
I put all the items from this off-grid system (well, not the solar panels) in a wooden crate to have it movable so I can take it to camping.
 
Chris Olson
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Markus Loeffler wrote:
Gas generators are certainly a reliable option but I dislike the fact that they burn gasoline and produce stinky CO2.
If you just want to have backup power for a few appliances you can do this by spending less than $2000 on a few solar panels and some batteries.


The thing with solar vs a generator for backup power is economic feasibility. Even off-grid we use generators for backup power. The conditions that mean a major power outage usually means poor solar insolation as well. A EM6500SX generator running at 80% rated load will produce 2 kWh in only 25 minutes. When you consider all the loads you need to run during a power outage - including fridge, freezer, furnace (and sometimes A/C in hot locations), sump pump, well pump, water heating, lighting, and ways to make food like microwave, electric stove or cooktop, etc. - a generator makes a lot more sense. We run all that stuff in our off-grid home every single day and it cost almost $10,000 just for the batteries for a system large enough to power it all. A $3,000 generator can power it with ease, and doesn't burn that much fuel when you consider what's at stake.

Even for off-grid full time living, the sun don't always shine and the wind don't always blow, yet life goes on. The genset is the one thing we can count on every single time when mother nature refuses to cooperate.

Burning gasoline (or diesel fuel) and producing CO2 is a matter of perception. The entire earth is a closed loop carbon cycle, so you can burn fossil fuels and they eventually get recycled back to fossil fuels. Basically only the "greenies" have a warped illusion of "saving the planet" by using solar instead. It's an unfortunate fact that the manufacturing of your solar panels and batteries is anything but "green".
 
Markus Loeffler
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Location: Altadena, CA, USA
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No doubt a generator has a wide variety of use cases. In case of pulling an entire house off grid it is certainly the easy way. And if you have a cabin in the woods where you spend some days per month it might still be the least costly option.
But if you spend $2000 on a device you maybe need once a year in a black-out situation then I would say that money is not spend the best way. If you live in an area with lots of sunshine the solar panel will save you money the first day you install it and you will reduce your co2 footprint. Creating a sustainable lifestyle is something we have to put all out efforts into.

Speaking about CO2: So we environmentalists have a "warped illusion of saving the planet"?
It certainly does not end with solar but keep on burning gasoline is definitely not the answer to climate change. A quick quote from the website of the EPA:

"Greenhouse gases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years. The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation."
 
Chris Olson
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Markus Loeffler wrote:
But if you spend $2000 on a device you maybe need once a year in a black-out situation then I would say that money is not spend the best way. If you live in an area with lots of sunshine the solar panel will save you money the first day you install it and you will reduce your CO2 footprint


While we have three quite large solar arrays here, and I have nothing against solar at all because we depend on it quite extensively, the power you produce with your solar panels is more expensive than what you can buy it for from the utility. All the people putting in grid-tied solar PV are paying for it with subsidies and "kick backs" to make it financially feasible. For us off-grid folks where generator power costs upwards of 75 cents/kWh then the solar pays off in fuel savings in our generators.

So IMO the way to look at residential grid-based standby power is that if it costs $5,000 to put it in by the time you buy the genset, install the wiring and transfer switches, etc., it becomes worth every dime spent the first time you have a power failure that lasts even a half day. Without it your life pretty much comes to a halt, and if the power is out a long time you can lose everything you have in your fridge and freezer, and if it's middle of winter the genset makes a difference between living in a home with no heat and running water vs not even being affected. I've lived off-grid long enough to tell you flat out that solar panels cannot do that for you. We have a $50,000 off-grid system here and we STILL depend on the generators.


"Greenhouse gases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years. The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation."


Ahhhh...... climate change. Well, I got news for the EPA. The climate has been changing on this rock since the day it was formed. There are points in the planet's history when atmospheric CO2 was a LOT higher than it is now (aboriginal coal-fired power plants causing it). And the Arctic Ocean was totally ice-free for almost 1,000 years from around 300AD to 1262AD. My wife and I are sailors, and being my wife is native Swedish and I am of Norwegian ancestry we also have a great interest in early Norse history, especially where sailing is concerned. Early Norse records stored in Trondheim were moved to Copenhagen in 1654 and subsequently lost in a fire during the early christianization of the Norse people. However the archives in Nuuk, Greenland that recorded the explorations of the early Vikings remained intact. Those archives tell of Swedish, Norwegian and Finnish sailors that sailed to Vineland (today known as North America) thru what is today known as the Northwest Passage from 411AD to 1262AD when the Arctic ice first blocked their passage to Vineland. The Viking expansion was VERY impressive - they traded with people in what is today Northern Canada, and were as far west as Russia and the Bering Straits, sailing across the Arctic Ocean. For over 800 years. And the settlements in Greenland and Iceland were diverse farming communities. The planet was a LOT warmer than it is today.

Some historians refer to this as the "Medieval Warm Period". Your "climate change" scam artists like to ignore it and the IPCC Third Assessment Report from 2001 even goes as far as to totally try to discount historical fact: "…current evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of 'Little Ice Age' and 'Medieval Warm Period' appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries"

So, from a history standpoint, "climate change" as it is presented today is a bunch of hogwash. It is a ruse to play on your emotions so a select few can establish a carbon trading scheme that is going to net them billions. The World Bank has already set up their CFU (Carbon Finance Unit)
http://www.worldbank.org/en/topic/climatefinance

There is NOTHING done on this planet by governments or big business for the "good" of the planet. It is all about money. And so far, their scare tactics and doctored "studies" are working on the general population. Won't be long and the money will flowing nicely from your pockets to theirs if they can make their scam stick.
 
Chris Olson
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For folks with utility power, moving off-grid is really pretty simple; locate the electrical panel in your house and identify the breaker in it that says "Main" on it. Flip that breaker to the "off" position. Congratulations! You are now off-grid. Now all you have to do is figure out how to survive without turning that breaker back "on". Some of us live this way 24 hours a day, 365 days a year because the utility lines don't come to our place. And our experience with this has formed rather narrow opinions on what works and what don't, and what's practical and what's not.

I made this video to show why solar power cannot be relied upon for standby power for a utility-connected home in most cases. There is too much fantasy out there where "renewable" forms of energy are concerned. The fantasy does not mean these forms of energy do not work - they do. But they work at the whim of mother nature, which is many times not inline with your needs. So, considering you are effectively off-grid when the power goes out, this video shows real numbers from a real world off-grid system that runs 24/7/365 supplying all of our power. And why a generator is still the best choice for reliable standby power



NOTE AND DISCLAIMER: standby power for a utility connected home can NOT be produced by a generator at the same cost that we do it for on our off-grid system. Our inverter is an expensive and very advanced unit that operates in synchronization with the generator and supplies power to loads that the tiny 2,300 watt generator cannot power by itself. A utility connected home requires a much larger generator that will burn more fuel per kWh. The video is not intended to provide a cost analysis of genset vs solar power - just to demonstrate why solar power cannot be relied upon to be there when you need it most in a standby power situation.
 
Theresa Brennan
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Thanks Chris for all the time you put into helping me understand better
 
permaculture is a more symbiotic relationship with nature so I can be even lazier. Read tiny ad:
Permaculture Playing Cards by Paul Wheaton and Alexander Ojeda
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