Solar energy for On-Grid home, that works when grid is down

6 years ago

I would like to have an on-grid(or off w/e considering price and upkeep) system that can also sustain my appliances when the grid is down. I live in a zone where there are blackouts at least 4 times per month, sometimes 2-3 days(and nights) in a row. Moving is not an option. I also wish to run air conditioning 24/7 in at least one room. What would be the most cost effective solution for this?

If I had to "cut corners" or make sacrifices to lower costs, at least I'd like being able to have power for the fridge, and one power outlet for personal cooling fan a laptop during the day or the night, at times when On-Grid power is not available.

Featured Answer

PRO

Floors like glass

5 years ago

Look into the sonnen batterie system. Their bullet points directly correlate with your needs. It is a smart solar home utility. Not only does it save power for when you need it, but unlike others it purposely powers your home when your electric bill runs the hottest. It is an energy utilities nemesis, and allows the "community" of sonnen members to share power with each other and assist each others power needs. So many people are fearful of the prospect of full on investment in solar because of lack of education and in many cases, the homeowner coz I guess they have not taken the power back no pun intended. but this system fully put the control back in your hands, i believe, takes the guesswork out and has the added bonus of making you part of a community so help is always around the corner and not just from the company itself. I believe the precedence that this type of system is setting is a real evolution, weaning off of relying on utilities...and no i dont workbfir them :), but i do work on leed certified buildings,cradle to cradle materials, and have a lifelong passion for the art of building green. I would like ti be alive to see the transition, and more so feel indebted to help spur it on. There are also many other ways to give incremental bonuses to your existjng solar array. Solatube lightjng is one, solar hot water heating, solar vents-built into the side of a house, helps cool in summer, warm the air in winter. Actually i vehemently disagree that a few panels on the roof is where anyone should stop. Added cost-ive read as a concern, but isnt it always. If you have gone through the expense and effort of a grid tie or otherwise system, your math might be a bit off if you think stopping there and calculating your years til full repayment is job well done. Extreme example, but what if you had poor to no insulation on half or more of your outside walls? Your wonderful solar energy is going right out the window, and whatever you are saving, it could be double. One person on houzz mentioned changing all their bulbs to led, as the only change, and saw huge savings on their elex bill. Alot of these smaller ideas,not the sonnen, are relatively inexpensive and when combined achieve a sum greater than its total. I.e. if a roof adorned with solar panels saves you money, why not take multiple steps that each do the same, and achieve your ultimate goal, which is in every solar co's ads, independence, and real freedom isnt cheap, but its worth every penny. Especially in ways which are priceless, peace of mind, knowing you did truly all you could and not relive the guilt of stopping half way.

Comments (22)

PRO
Patricia Colwell Consulting
6 years ago
You ned to speak to solar experts , there are many choices for backup electricity , the simplest of course is just a back generator that automatically kicks in when the power goes off.
PRO
Austin Air Companie
6 years ago
last modified: 6 years ago
Solar in my opinion is a great option when the costs of electricity exceed around 20 cents per KWH from the utility provider AND you have the real estate (roof or other area) with unhindered access to the southern sky at a good angle not to mention the area (location) you live has a good number of sunny days.

If your cost for utility provided power is less than 20 cents per KWH the advantages with solar run out or at best is a break even scenario with more hassles in the way of maintaining your solar grid. (The grid is tied to an inverter to convert power from DC to AC.) The panels typically last about 25 years, but power generated can degrade before the 25 year mark.

If you want a back up for when or if the grid power fails the maintenance costs stack up if you choose battery back up that is tied to your solar panel array to store power for when the grid goes down. Depending on the number of batteries the system contains and voltage requirements for loads you are running during an outage, the battery system may become depleted depending on how long the duration of power outage. So there are many variables to consider especially if you want air conditioning to run during an outage.

If you have natural gas hook up you could have a generator installed with switching to auto switch on when power becomes absent from the grid. You could use this in addition to solar, as if the grid power goes down and it's not sunny enough to run off solar power the natural gas generator kicks on to power the home or parts there of.

You could just use a natural gas generator with the auto on switch when power disruption is sensed and forget about the solar array.

The biggest things to think about are cost / noise. The generator will be noisy and I've been to homes, one in particular where it was running via some programmed maintenance test and it was quite loud. If you don't have natural gas available you're in a tough spot for options.

In Texas with utility rates in most cases below 10 cents per KWH a solar array cost would be lucky to break even when you consider avg... $25-30K cost of the array and utility savings of about $70 a month your savings come to about 21K over a 25 year period. This amount does not figure in damage due to hail or other problems that require repairs to the solar array.

It's best to size the array appropriately to what you need. In Texas as an example, the utility companies at best typically pay transmission costs to any amount the solar array makes over what you use. Depending on the provider they may cap this amount as well. Currently transmission costs (in Texas) are around 3.5 cents to 4 cents per KWH. So at those rates you are basically giving the excess power away that your solar array provides back to the power grid.
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im no expert, been reading/researching it, specifically for later use. Talking with a few folks, heres what im looking at and this is presented purely for though provoking info off the grid is over rated and not neccessary if you ask some solar users(myself included) yes its all romantic thinking about the self sufficiency aspect of it, but honestly probably not worth it in a urban/semi rural area. grid tie is ALMOST a great answer, but if you lose power in a storm, doesnt matter how much solar you put on the roof. it still has to be stored and disseminated. ive been thinking of a hybrid type system(again for the future) where id be grid tied 99% of the time, but id also have battery storage and a set of outlets (the garage for instance) specifically for power outages/storms. i could still run a small refrigerator/freezer(mine in the garage now runs at about 2.5a) and a small TV, couple of fans and maybe flourescent lighting. off the grid. indefinitely. yeah hot showers wouldnt happen, and cooking would be strictly open fire/grill, but you know you could go as far as you want. that may very well be a good place to start for you. my uncle is off the grid in the escalante canyon, but he didnt go all in at the beginning. work your way up. Now heres the reality of alternative energy. it requires regular maintenance and periodic replacement of components. batteries are likely the most expensive part.(based on a small 35w garden pond experiment i recently completed- ha, i turned a 100$ pond into a 400$ pond in a week, more on that in a minute) and theyll need to be replaced at some point. just the way it is. same with panels, at some point theyll need to be replaced. just keep it in mind as you deliberate. as far as panels go. thin film is cheaper, eficiency is less, and life span is shorter. mono/poly crystalline is more efficient, lasts longer, but exponentially more expensive. batteries. i could go for weeks on info ive found out about solar power storage, AGM, lead acid,gel cell, etc etc etc. either way, you get what you pay for and you will pay. heres a general idea of expenses based on my very limited experience during one solar experiment. 1 30 gallon pond kit- 100$ northern tool 35w monocrystalline panel with charge controller- 80$ ebay 8w 12v DC pump- 40$ online 34AH AGM battery(electric wheel chair battery) 90$ batteries plus. various wiring/fasteners/etc- 30$ add in labor(it was me, i make about $20+ per hour) for 6 hours of work installing only. now i have probably 5-6 years of off the grid power for my stupid 30 gallon pond. then ill have to replace the battery, maybe the charge controller. hoping the panel lasts at least 10, maybe 15 years. nevermind the pump. that could go any minute now muliply that by 50-100 (sans pond kit) and add permits, inspections, engineers, designers, electricians. i dont even know what that would cost. and you should have a beginning idea of what it would cost to do a house off the grid. yep youre self sufficient, but it could take years to get the return on investment, and then youd be looking at regular replacement of something, so youd be better off, but not free. that said, i like my pond. the birds like it, and im sure the mosquitos will too this summer(crap theres another 30$ in either fish or dunks, plus algae control, talk about a 64$ tomato) i did learn A TON about solar though. matt
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Just to fill in the missing data on battery storage, I think I may now understand the numbers that "SolarPowered" presented. They are accurate, in terms of the numbers and the math, but don't represent the situation correctly. Let's say you needed about twelve killowatts of energy storage (a modest amount, but certainly possible with a small amount of conservation). Surrette 6CS-17PS Battery 546 Amp-Hours, 6 Volt DC Regular price: $992.00 Sale price: $791.76, 4/$3,120.00 Let's round this off and say 500 amp hours at 6 volts times 4 batteries = $3000/500 * 6 * 4 = $0.25 per killowatt hour of storage. So the total cost of your storage for the ten to fifteen years that you will get out of these industrial quality batteries is 25 cents per killowatt hour...per day, times 10 years... So in actual fact, since you will be putting 12 KW-hours of energy into and out of the batteries many times during those ten years. Each killowatt-hour only costs about .25/365*10, or about 0.007 cents per killowatt hour. So, while it is a significant cost in setting up your solar power system, it is not, contrary to solar Powered, going to make it impossible for you to make your own energy cheaper than the power company can. I think $30K is a more realistic number for an off grid system for a whole normal sized house. If we take off the $20k we don't have to pay the electric company to string a wire to our property, we are looking to generate more than $10K worth of energy in the same time we would pay that much in monthly bills. Using very round numbers, let's say a typical monthly electric bill might be $100. At that rate, our power is free after the first 8 years. So the $20k we're not paying the electric company doesn't pay for our whole system, but it reduces our payback time from an impractical 24 years to just 8 years. Since the solar panels and many other parts of the system are expected to last twice that long, I think it's a pretty fair bet that the system will save money in the very long run. That, coupled with the fact that you get to send your favorite obscene gesture in the general direction of "Big Power", and operate your home with a near zero CO2 output and you are free of concern over power outages and rising costs...I would say it is a no-brainer. If you don't have the big up-front cost to connect, it could easily go the other way though. jp
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O.K., now I feel like I am getting somewhere. Gblentz, I probably will try to pick up the book soon. I did check out their web site. It is well-done. I appreciate people that are that generous. It takes time to document projects that way. Oh my, no way I would try to sell power from a NG generator to the local POCO. I did not even though of interpreting brickeyes post that way so I was kind of mystified by it, but I tried to make the most of it. I dont think that I am as crazy or dumb as I may appear. I am probably just not expressing myself well. Please give me another chance. I understand completely that I need batteries or a generator if I want to have power in my house when there is no sun. There are other alternatives, of course, but pumping water uphill, freezing ice, flywheels, compressing gas, or other unconventional things to store energy and recover it later would be harder to implement since they are not exactly OTC technology for residential applications. At my house, we would be perfectly able to get through a few days or a couple of weeks of power outage with a relatively small generator to keep the freezer frozen and operate a small air conditioner at night. My tradition is that, in the evening, I go to bed until the usual dark spell passes over. I know that I am trivializing that somewhat because I would have to start shedding loads as the sun gets lower and bring them on with some thought and calculation in the morning. The AC load, nevertheless, is low at night. In the daytime, I would like more AC and having, for example, 12 KW worth of panels on my roof with the inability to run even a 2 ton AC system would be very, very frustrating. I could even get away with running the refrigerator and freezer only during the day. So the inverters need batteries to run the regulating circuits because they can not boot-strap. That, I understand. That would require only token batteries compared to what I would need to run an off the grid system that I might expect to run a home "normally". The other mentioned problem with no batteries on a system that is not grid-tied, is that to get the most out of it, I need surge capability and the best way to get that is from batteries. That I understand as well. Still, if I am putting minimal demands on the PV system, maybe token batteries would suffice. That means that I might require an EE to do some calculations for me, at worst. Honestly, I think that I could figure that out and have an EE check it for me. Last, the plan to have a small NG generator to hobble along with at night and to keep my freezer cold if the array blows off my roof, or blows off with my roof. These are real concerns. After Katrina, I lost the contents of a 21 cu ft freezer. Of course it was under water and I lost the rest of the house as well. My wife and I both like to cook and we have a lot of food around. Losing the freezer contents is something I dont want to repeat if there is just a power outage. Insurance does not cover the raw materials and there is a lot of labor in it. If I have a small generator, it might be able to boot-strap the inverters, but I really dont care if I can do it with minimal battery capacity. I know how to use a hydrometer, I know the difference between distilled, deionized and reverse osmosis water, and I know that mixing hydrogen and oxygen in confined space can be a really bad thing. The generator should be able to provide surge capacity for motor start-up and take up some slack when a cloud passes over. It would not be as fast as a battery, but again, if I am making minimal demands on the PV array, my guess is that it would be fine. So what stands in the way of my vision? Have I got the engineering all wrong? Are code issues going to torpedo it? Can I start to hire people to build it?
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mike_home
6 years ago
You can buy a 9KW Generac generator for $2395 which would be enough to power most of your house. Larger units are available. To that you to add the wiring and transfer switch. It can run off of natural gas or propane. The natural gas is nice since you can run it indefinitely.

The sound is rated at 66 dB(A) from a distance of 23 feet. If noise is a concern then unlike an AC condenser it can be installed further away from the house and surrounded by shrubs.
PRO
Austin Air Companie
6 years ago
last modified: 6 years ago
The generator is loud Mike (louder than a AC condenser as I was at a home a year ago in which the thing was running on a maintenance test, I question your 66 dB rating because most condensers run at 70 dB. I can tell you right now, covering it with shrubs isn't going to do much and even if power never goes out, the things runs on periodic timings to test the thing.

If you want peace and quiet solar panels are the way to go, but they have their limitations and the cost is rather high.
Selita Esoj
Original Author
6 years ago
last modified: 6 years ago
Hi, thanks for your replies. Just wanted to add that here there is no snow or hail, and the cost of electricity goes from 23 to 27 per kwh. A propane generator sounds like a good option(since it could share a gas line with the dryer) but houses in this neighborhood are less than 10 feet appart from each other(except in the back which is like 20-30 feet appart) so I'm scared that could be a problem. The house is about 1000 feet square ( 347 square meters) and has a flat roof, completely empty. There is sun all year long except for the ocassional rain(tropical weather).
sktn77a
6 years ago
That generator is NOISY - I live next to a guy with one. The 66dB is a weighted measure which bears no reality to what you hear!
Selita Esoj
Original Author
6 years ago
If the generator is too noisy, I rather not start a war with my neighbors. What other options I have, given my circumstances?
yvonnecmartin
6 years ago
I will add that our Generac generator, 9 KW, is extremely quiet. It is right outside our guest bedroom window and we have to go into that room to hear if it is on during its weekly exercise. That said, our neighbor has a whole-house generator that sounds like a diesel truck even through thick bushes. So, if you go for a generator, be sure to consider the noise.
Jim Mat
6 years ago
last modified: 6 years ago
In the United States, Tesla sells a 14kw battery for home installation. In the old days, one would purchase as many Rolls batteries as needed/ wanted. Rolls are probably the most cost effective if one knows what to do, if you have to hire someone to install, hookup, convert the electricity, the Tesla may be a better choice.

edit to add, the Generac cost is not $2,395. The Generac mentioned is $6-8k installed. The Tesla installed is ~$10k.

Regarding price of electricity, nice to know, but if the utility is not able to consistently supply electricity, the price per kWh doesn't matter. I live in an area where a black/brown out is unacceptable to some businesses. Those users spends hundreds of thousands of dollars for 200-400 kWh generators and onsite diesel fuel storage.
weedmeister
6 years ago
How much power for how long a time? Are your outages for minutes, hours or days? When you say one room airconditioner, do you mean a small 120v window unit?
Selita Esoj
Original Author
6 years ago
last modified: 6 years ago
At very minimum, in cases where power may be gone for up to 48 hours, I'd like to run:

a fridge that's 634kwh/cycle(even running it half of the time would be fine, probably).

An dc inverter air conditioner of about 9000 btu. Efficiency rate 16-21(havent got it yet). In a worst case scenario where power seems like will be gone like 24-48 hours a standing cooling fan would be ok(those are like 50w i think).

A laptop computer and 2 mobile smartphones.

Let's see... common bad scenarios would be:

No grid/blackout on a sunny day 12-48 hours(covered by the pv cells?)

No grid/blackout during a very cloudy day 12-48 hours(idk what happens there)

No grid/blackout during the night(after a day that was cloudy) 12-48 hours
Jim Mat
6 years ago
Based on your scenarios, a battery storage system is my recommendation.
PRO
Austin Air Companie
6 years ago
last modified: 6 years ago
yikes 23 to 27 cent a KWH? You would think they would want to keep those juices flowing at those prices.

Solar is definitely the way to go if you can given your utility grid prices, battery back up would keep you from losing your mind due to the noise of a generator... just remember to maintain those batteries or the bliss will go down hill rather quick.

Also you want to size your battery array properly, because over draining / over charging will wear a battery out quicker if the array isn't set up right.
mike_home
6 years ago
The sound specification I posted is from the Generac data sheet. It is supposed to be the measured sound from a distance a 23 feet. We don't know how this measurement was done so I agree it may be deceiving.

The Tesla Powerwall (battery) is an interesting device. But it is intended to be connected to a DC source like a bank of solar cells. Solar cells and a battery are very quiet but also very expensive. I have not been able to find a specification sheet. If you don't have a solar bank, then you would have to install a AC to DC converter to keep the battery charged. Depending on the size this could be another another expensive item. I am skeptical you could power most of a house for 24 hours without recharging the battery, but it may be possible.

If noise is a key factor then you should look into a Honda generator. These generators are the inverter type which tend to be quieter. The 7 KW models sells for $4500. The noise specification listed on the data sheet is 60 db(A) at full load, 52 db(A) are quarter load. The fuel is gasoline. I am not sure if it could be converted to propane.
suburbanmd
6 years ago
My Generac natural gas generator runs the weekly exercise at half speed to reduce noise.
PRO
Austin Air Companie
6 years ago
last modified: 6 years ago
It would be counter productive to install battery array without the solar array.

The solar array is there to cut cost and recharge the battery array at lowest possible power generation cost when the sun is shining brilliantly. (realize at over 20 cents a KWH for grid power, it's cheaper to create power via solar at those price points.)

The battery array is really only there for when the sun is not shining or not as much as it normally does to limit power disruption.

In other words, the system would still be tied to the power grid. Power from the grid would be used normally when sun isn't shining. The idea is when the sun is shining the solar array produces enough to run the whole home as well as recharge the battery array.

The battery array is only there to get thru 'various' no grid power events when the sun light isn't available.
just_janni
6 years ago
I thought that Tesla stopped selling their battery enclosures. And boy - were they expensive.

I can't see why solar and a decent (quieter) generator isn't the right answer here. I think the batteries are going to cost an arm and a leg, and take up a lot of wall space (if Tesla is even selling them)
mike_home
6 years ago
If most of the power outages occur during storms, when there is rain and cloud cover, then the solar array is not going to be much help. The run time of a battery is directly depended on how much current is being drawn. You may only get 5 - 10 hours of operation. Then once it is depleted, it may take several hours to recharge.
homepro01
6 years ago
last modified: 6 years ago
Tesla still sells the powerwall. tesla released the gen 2 models and deliveries are within 90days I believe.

Solar and the powerwall would be my choice. As someone who lives half a block away from a natural gas generator that tests weekly, they are loud. Especially at night when there is no power or it is really quiet. I have a Honda gas powered generator that is super quiet but it has to be turned on when the power goes out.

The Tesla Powerall has been installed quite a bit in Australia because of their rolling black outs. You may want to read some articles on this. Tesla is also installing micro grids in places where power reliability is low and Diesel is very expensive. The micro grids are based on these Tesla powerwall.

Ordering a powerwall

Article from Teslarati about Powerwall in Australia
sl v
6 years ago
last modified: 6 years ago
Does anyone have a Tesla setup in the midwest US? How has it performed so far? Planning a custom home construction. Looked forward to going this route initially but on researching it looks like it will take too long to be price effective; weighing system costs vs time it would take to reach break even or cost savings point.
mtvhike
3 years ago
Floors like Glass, how does your sonnen battery system compare with Tesla's? I've never heard of that company. Ok, your post is 3 years old, so maybe they are out of business!

Solar energy for On-Grid home, that works when grid is down

Floors like glass

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