Jump to content

Power outage solutions: generator versus solar + battery


roni

Recommended Posts

Julian Sprung's talk came at a great time.  Unfortunately I didn't act on it before the power outage but got through it relatively unscathed.

 

Have been weighing a couple options but wanted to get some input and make sure I wasn't missing anything.

 

Standard generac whole house generator with automatic transfer switch.  

 

Pros - known commodity, dependable, set and forget, best for multi day outages, especially if connected to natural gas.  Barring catastrophe (bomb/sabotage/terrorist attack), basically good to go even if the outage were a week

 

Cons - expensive and if you don't have an outage, just sits there, plus ongoing maintenance costs

 

Solar with battery backup

 

Pros - benefit from solar even when there isn't a power outage, especially with a powerwall or LG battery backup helping with storage and energy balancing (basically store energy during the day that's excess of what you're using for the night when the sun is gone).  Can act as a battery backup for essential stuff (tank, fridge)

 

Cons - very, very expensive though it slowly pays for itself.  Technology is advancing rapidly and may be paying for tech that will be dramatically cheaper in 5 years, especially the batteries.  Can't really set and forget.  Unless you spend tons of money, the batteries can't really handle the load of the HVAC.

 

Am I missing anything?  I know Julian was planning on going with option 2 but in my mind, the cost is still prohibitive and it requires more management from the individual.  For example, if we had to evacuate the area, the whole house would still run everything even if the evacuation was a week whereas the solar would run out after 2-3 days.  

 

My thought is option 2 will become the winner down the line but isn't there yet.

 

 

Link to comment
Share on other sites

I've been working on the math for solar since Julian's talk.  See if this makes any sense.

 

One thing solar has going for it at least for the next two years is that you get a 30% federal tax credit for installing it plus whatever else you'd get from the state or county, which is nothing right now in Maryland.  Montgomery county just started an "energy storage" credit, though, which pays for part of a battery install independent of solar, so maybe other locations have that sort of thing.

 

You get the tax credit all in one chunk, so it can be used to pay for a loan you might take to get panels installed and can pay for them for quite a few years.

 

For instance, I pay an average of $230/mo for electricity for 1533 kWh of electricity on average per month.  We get an average of 4.25 hours of full sun per day in our area, so I'd need a 15kW system (assuming 20% losses) to totally cover my yearly electricity needs and generate me $230/mo.  A 15kW system would be about $40,000 including estimated $16k of  installation from freecleansolar.com.  At 5% APR that would be $424 per month for a 10 year HELOC before any tax deductions for the interest.  

 

I'd be paying $230/mo on electricity anyway, so that leaves $194 extra that I'm paying each month.  But I'll get on average around a $23 tax deduction on the interest on that HELOC each month (averaged over the life of the loan) so that drops it down to $171 extra each month over what I would have paid already for electricity.

 

Next the feds will give me $12,000 back on my taxes for the install that I can use to pay that extra $171, and I can use it to pay the extra $171 for 5 years and 10 months of the 10 year loan.  

 

So I can have solar on my roof and pay nothing extra over what I'm paying Pepco now for almost 6 years.  I still wouldn't see any financial benefits during that time, though, but could spend those 6 years saving the money for the extra $20k I'd have left from the initial loan.  You'd start seeing benefits once the loan was gone, but using the tax credit to pay off the loan for a good long time spreads out the initial financial hit nicely and makes much more sense to me than leasing panels or getting a fixed, slightly discounted kWh price from a solar company that is putting their panels on your roof.  It might make sense to put the entire credit right on the loan at the beginning to avoid paying interest on that amount depending on what your cash flow looks like.

 

The math looks a little worse if you include batteries which can be as expensive as the panels but the math looks a lot better if you do the panel install yourself and just get an electrician to do the permitted hookups.  

 

Plus at least with batteries you can still run the house when power is out.  

Link to comment
Share on other sites

(edited)

Alan,

 

I think from the perspective of the panels, you might very well be right.  But that's really only one part of the equation in my opinion.  For me, the bigger issue is the power backup.  1 battery is useful and may be enough for tank needs simply because it'll allow you to load balance.  Currently, when you produce excess energy you can sell back to the grid for pretty much what you buy it for but in the future, that might change as solar becomes more readily available.  The battery allows you to avoid the grid for a large portion of your needs.  A single Tesla powerwall (which isn't available as far as I can see) or LG equivalent was around 8K with install.  Something like that could probably run a decent sized tank and fridge for 2 days but not much after that.  My tank, fridge and heater were about 45% load on a 6250 gas generator during this last outage.  

 

The other problem with solar right now, imo, is that by the time the panels are finally paid off, they may be obsolete.  Think about the changes in cpu tech or even LED technology.  5 years ago the AI LEDs and radion generation one were louded as lasting forever.  Not many people have those initial lights, not because they don't work but because technology has advanced so far.  Contrast to a more stable tech like T5s.  T5 tech hasn't changed that much and a good fixture from 5 years ago is still a good fixture.  I'm not sure where solar is but when I think about Tesla eventually coming out with solar that also doubles as your roof, it's hard to think that the technology is yet mature enough.  

 

btw, I'm getting bids of about 20K here in Virginia after credit.  I can forward you the info if you want.

 

My current working plan is whole house generator for tank/house/pet safety and peace of mind.  I'll probably look at solar/battery backup for load balancing/reducing carbon footprint/getting off the grid as the Tesla powerwalls become more readily available and the technology matures with the eventual goal of having the gas generator as a worst case scenario backup.  

Edited by roni
Link to comment
Share on other sites

What does a whole whole generator running off of natural gas run in terms of install cost and maintenance? How long would it last running two tanks, a fridge, lights, and HVAC?

Link to comment
Share on other sites

 

What does a whole whole generator running off of natural gas run in terms of install cost and maintenance? How long would it last running two tanks, a fridge, lights, and HVAC?

 

 

 

Depends on the size and how often it runs. Paid $1700 for a Generac 17KW plus an additional & 1500 for the install, got a good deal on it. Runs about 15-20 mins. one day a week to keep the battery charged. A tune-up runs around $20-$30  bi-yearly, which I do myself that consists of changing out the air filter, plugs and oil.

 

Got after the Derecho. Pepco upgraded the power system and it came on once, maybe twice since I got it. Before the system upgrade we would lose power if the wind blew hard.

Link to comment
Share on other sites

From what I've seen a whole house generator and tank of propane (we don't have gas service here) would be about a third the cost of a solar install including batteries that would last a few days like roni says.

 

Roni, I think I'd get more than 2 days on a single 9.8kWh LG Chem Home battery if I didn't run the lights.  Running the heater would be quite a whack, though.  Plus the fridge.  I was considering two of those batteries or a bigger 30kWh for the same price made with AGM lead batteries.

 

What size is your 20k after tax credit system and did it include battery?  I was figuring 28k after tax credit just for the solar for 15kW system.

 

My wife's primary concern is similar to yours, tech advances making our big investment obsolete before we're done paying for it, heh.

Link to comment
Share on other sites

Depends on the size and how often it runs. Paid $1700 for a Generac 17KW plus an additional & 1500 for the install, got a good deal on it. Runs about 15-20 mins. one day a week to keep the battery charged. A tune-up runs around $20-$30  bi-yearly, which I do myself that consists of changing out the air filter, plugs and oil.

 

Got after the Derecho. Pepco upgraded the power system and it came on once, maybe twice since I got it. Before the system upgrade we would lose power if the wind blew hard.

 

That's an amazing deal on that generator.  I've only seen them for around $4k plus install.

Link to comment
Share on other sites

Depends on the size and how often it runs. Paid $1700 for a Generac 17KW plus an additional & 1500 for the install, got a good deal on it. Runs about 15-20 mins. one day a week to keep the battery charged. A tune-up runs around $20-$30  bi-yearly, which I do myself that consists of changing out the air filter, plugs and oil.

 

Got after the Derecho. Pepco upgraded the power system and it came on once, maybe twice since I got it. Before the system upgrade we would lose power if the wind blew hard.

Wow, i'm getting much higher quotes.  For a 20K with autotransfer switch and natural gas line, I'm getting 8-11K installed.  It cost me about 250 yearly for a service when I had one in stafford.  Maybe I need to learn how to do it myself ;)   can you shoot me the info for the company that put in yours?

 

 

From what I've seen a whole house generator and tank of propane (we don't have gas service here) would be about a third the cost of a solar install including batteries that would last a few days like roni says.

 

Roni, I think I'd get more than 2 days on a single 9.8kWh LG Chem Home battery if I didn't run the lights.  Running the heater would be quite a whack, though.  Plus the fridge.  I was considering two of those batteries or a bigger 30kWh for the same price made with AGM lead batteries.

 

What size is your 20k after tax credit system and did it include battery?  I was figuring 28k after tax credit just for the solar for 15kW system.

 

My wife's primary concern is similar to yours, tech advances making our big investment obsolete before we're done paying for it, heh.

Hmm, it was 8.3 Kw with a net cost of 15K (after rebates).  MIght be a little undersized but I didn't really pursue it as vigorously.  no battery.  

Link to comment
Share on other sites

The cost-benefit calculation is individualized. There are reusable energy tax credits. But you need to consider 1) Do you have the right setup to make this work? Do you have exposure that will get sufficient sun? (I don't. I live in the woods under some 100' oaks and poplars on the western slope of a mountain. So it's shady in the summer and the sun is low in the winter. What are the installation costs? If you can do it yourself, that changes the calculations quite a lot. (Paul B. installed his own solar system on his home near NYC.) And then, of course, there's maintenance and replacement.

 

For me, my best option is probably a large generator. But then I need to solve the fuel problem. My only options are a propane or oil/diesel. But, for both of those I need a tank. And power entry on my home is about 25 feet from a steep ravine so I'd most likely be looking at a second propane tank strapped close to the house. (I have another propane tank on the other side of the house that's used for our gas stove.) The thing I don't know is how long I could run a generator on, say, 50 gallons of propane....

 

For now, though, I have a 5KW generator and a long (and heavy) generator cord that plugs into a port on the side of the house. I use an interlocking device on one of my two electrical panels. If and when we lose power, I can run 

 

1) Shut the breaker down on my interlocked panel.

2) Shut down all the breakers on the panel.

3) Connect my generator to my house via the cord (the generator sits running under the deck in the open air).

4) Go back into the house and turn on select, pre-determined (and marked) breakers.

 

My well pump is also on that same panel, as are my fish room, select rooms in the house, deep freeze, fridge and the outlet that we use for the coffeemaker in the kitchen (my wife's demand).

 

We only had power go out once on us for a few hours in the last 7 years here and the setup worked well.

 

Unfortunately, if the power went out when the house was empty, all this wouldn't do much for us. Of course, if we were on a propane powered auto-switching generator, it would only work for as long as the propane lasted and that might not be as long as we'd want to as it might try to drive our heating / cooling systems, eating a lot of fuel.

Link to comment
Share on other sites

I agree with what Alan said.

In my case the math made sense for me.

My average monthly bill to Pepco was $160.

When i looked at the solar option, it would cost me $170 with the finance option.  I reckon, I was paying Pepco about $160 per month anyway so paying an extra $15. was not a big deal to own the system and get ALL the benefits. I got the federal 30% tax credit plus an extra $1000 for MD. Plus i got Solar Renewable Energy Credit (SERC)s 

At the time I purchase my system (10kWa), the SERCs  were selling at $150 per credits unfortunately, that value has been reduced to about $15/credit, last time i check. Last year I got a $600 check which i used to further pay off the loan. At this rate, I would have payed off the loan years sooner. Now it will take a bit longer because of the decrease SERC value. But at the end of the deal the system is mine.

Yes, technology gets better, but its better than nothing. The panels now are about 20% efficient and they will only get better. But if you are going to have to pay Pecpo anyway, why not buy/finance the system anyway?

 

The Tesla battery will be a game changer once it is available. Then you will be able to live off grid and rely solely on the battery. It will certainly worth the cost of the battery because now enen though i make "free" power, when the grid goes down, i loose power too.

 

The other consideration about the generator too your carbon footprint.  I want to be as green as possible.  Remember, burning fossil fuel leads to increase CO2 and acidification of the water, increase water temp and ultimately coral bleaching which adversely affect the reefs and our hobby.

I am all about going green. Solar fits that bill

Link to comment
Share on other sites

I went with the 22kw generac and ATS. Installed it myself. Quite a bit of work due to the length of the propane line. But I paid about $5k for the generator and materials. I suspect it would have been about $10-12k to have installed. My house already had a 1000 gallon propane tank, and propane is pretty cheap the last few years.

 

Overall I am happy with it. When the powers goes out it is very nice not worrying about setting up and fueling a portable. The unit was leaking oil due to a crack in the engine block, which is disconcerting, but Generac replaced the entire engine under warranty. Maintenance is little to none.

 

Solar wasn't feasible for me as I live in the woods mostly.

 

Not sure I follow the comment about generators and carbon footprints. Not that I don't support being green, all for it, but the emissions a 1 liter propane engine generates running for 5 minutes every other week is nothing compared to a vehicle you drive to work unless it's a Tesla.

Link to comment
Share on other sites

Isn’t Sean from F&F doing whole house generators now? Maybe time for a new wamas vendor.

 

 

Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

Isn’t Sean from F&F doing whole house generators now? Maybe time for a new wamas vendor.

 

 

Sent from my iPhone using Tapatalk

I know that he wanted to become a power company lineman just as the store was closing. 

 

Just sent him an email and gave him this link.

Link to comment
Share on other sites

Not sure I follow the comment about generators and carbon footprints. Not that I don't support being green, all for it, but the emissions a 1 liter propane engine generates running for 5 minutes every other week is nothing compared to a vehicle you drive to work unless it's a Tesla.

 

It wasn't about generators and carbon footprints.  It was about commercial power from the grid and carbon footprints.  Since backup generators don't do anything about your daily energy use, the daily power will still be coming from mostly fossil fuels.

Link to comment
Share on other sites

While solar + battery can reduce your carbon footprint, we may also be creating a disposal problem downstream. Recycling these batteries will become even more important. It's possible that (in the case of a generator backup replacement), over the long haul, a carbon-based fuel and an engine sitting largely idle until needed will have less of an impact than batteries. 

 

This thread has got me thinking again about whether or not I want to put in a whole-house generator with a new propane tank. As I get older, having something that automatically kicks on would be a nice thing to have.

Link to comment
Share on other sites

It's true that it is more complicated than just looking at the immediate offset. 

 

Often carbon footprint calculations don't take into account the massive requirements in power plus environmental harm that results from manufacturing solar panels, mostly in China these days, and batteries.  I haven't seen the math of the entire lifecycle of solar panels and batteries before, but I'd be curious to see a holistic look at the whole thing to try to asses how "green" they really are.  

 

Some huge percentage of the lead in lead-acid batteries is recycled, but I'm not sure how effectively lithium is recycled in the newer batteries.

Link to comment
Share on other sites

Some huge percentage of the lead in lead-acid batteries is recycled, but I'm not sure how effectively lithium is recycled in the newer batteries.

It'll be more important as the industry grows. I'm not sure there's an economy of sufficient scale at this point to make it worthwhile to support a large number of players. But I'm sure that day is coming.

 

Hydrogen-Air fuel cells are, when you consider losses in manufacturing, distribution, and carrying it around in a vehicle are about 20-25% efficient. I don't know if that considers the losses to produce the power that powers the manufacturing plant (losses further upstream). That's about double of gasoline and internal combustion engines. Neither have industrial-recycling potential (or losses).  I know that there's still a lot of discussion about battery disposal as electric vehicles (with metal-ion batteries), but I don't think that I've seen a figure for lifecycle energy efficiency. I wonder if you can improve on Hydrogen fuel cell efficiency with small-scale on-premises production of hydrogen for power back up purposes - whether the trade for transportation / distribution is worth the added costs of production on a smaller scale. We've got a few years before that's a reality, though. For now, my only real option is going to be a carbon-based fuel source and an internal combustion engine as a backup power source for my house. 

 

Food for thought: Sunlight-to-hydrogen through photochemical water-splitting is about 12.5% efficient (in the lab). That would make Sunlight + water to-fuel-cell-vehicles about 4-5% efficient end-to-end. That doesn't seem like much, but the widespread availability of the reactants and the environmental gains might make it worth it someday. 

Link to comment
Share on other sites

funny enough I did my PhD research on using thin metal films for hydrogen storage.  Fuel cells are very cool, but they're essentially a battery technology.  Storing large amounts of hydrogen is fraught with issues even after first generating those large amounts of hydrogen (which doesn't exist in nature as H2).  Those are the main reasons everyone isn't driving around in a fuel cell. 

 

The second reason that they're hard to do is that you need to remove the water that's created in order to expose that reactive surface to the hydrogen and oxygen again to make more electricity.  Water has a high surface tension and wants to stick around.  There is a huge amount of materials research going on right now on just that problem: how to get the water out of the cell quickly and reliably.  Plus the catalysts tend to be precious metals that are also expensive, heh.

Link to comment
Share on other sites

I'm guessing that heat from the fuel cell probably won't overcome the latent heat of vaporization to evaporate off the condensed water.... So you need some sort of hydrophobic surface that breaks the surface tension and leaves a reactive surface. I wonder if some sort of engineered nanostructure could be devised that repelled water non-chemically.  Not an easy problem to solve. But, then again, if it were, we'd be there already.

Link to comment
Share on other sites

Nanostructures are what some I know are trying.

 

They’re depositing the electrode metals on nafion membranes with very special structures. Nafion conducts protons (hydrogen nuclei), but is an electrical insulator.

 

They do measurements at our place because we can see right through all of the metal structure of the cell to image where the hydrogen sits with a pretty fine resolution.

 

This is off topic, though. If I get a solar install with batteries you can bet I will post up here with my experiences. Wonder if I could log the generation using Apex Fusion somehow. 8)

Link to comment
Share on other sites

Nanostructures are what some I know are trying.

 

They’re depositing the electrode metals on nafion membranes with very special structures. Nafion conducts protons (hydrogen nuclei), but is an electrical insulator.

 

They do measurements at our place because we can see right through all of the metal structure of the cell to image where the hydrogen sits with a pretty fine resolution.

 

This is off topic, though. If I get a solar install with batteries you can bet I will post up here with my experiences. Wonder if I could log the generation using Apex Fusion somehow. 8)

Yeah, we're getting way off on a spoor. However, it did have roots in the right place and went along with questions related to environment and conservation...

 

 

Wow, i'm getting much higher quotes.  For a 20K with autotransfer switch and natural gas line, I'm getting 8-11K installed.  It cost me about 250 yearly for a service when I had one in stafford.  Maybe I need to learn how to do it myself  ;)   can you shoot me the info for the company that put in yours?

+1 to roni. Xabo, shoot me some of the info as well. My situation may be different, but may be worth finding out more about from your source.

 

Link to comment
Share on other sites

(edited)

Solar is a great long term investment. Everything is covered for 20 years from roof leaks to inverters. At this rate I’ll be paid off lonnnng before the warranty ends. (And if electric charges rise, even quicker) Let me know if you are interested in talking to someone and I can put you in for a discount. (It’s the only way to get a discount) I did not buy the battery sorry if I derail this. The picture is over the life of the system it’s a couple weeks shy of my 1 year annerversary. Couple of honest opinions: 1)not recommended if you will move in less than 10 years. 2)a southish facing roof helps pay them off a lot quicker 3) the lease option is great if you don’t have money down but they take a good percentage of power production. 4) my roof wasn’t big enough to cover my usage (because of the fish tank ;) 18d00b7f8e20a9f95a316319c1e3e6c9.jpg

Edited by gmerek2
Link to comment
Share on other sites

One thing to note about solar city is that you have to buy the panels (loan or cash) in order to claim any tax credits.  If you lease the panels from them, you can't claim the tax credits.  I have solar panels from solar city.  The electricity I generate goes back to the grid and I get a credit from Pepco for whatever I produce.  I can't store it for use at night or on a cloudy day unless I get the powerwall.  Before my tank, my electric bill was often negative.

 

My panels have produced 712 Kwh year to date. Last year they produced 5,200 Kwh. The panels have been on the roof since Nov 2014 and total energy produced ~17,100 kwh.  ~5 kwh/year.

 

right now at 10:35am they are producing 3,400 watts @ a savings of $0.51/hour

Link to comment
Share on other sites

So, back to whole house generators.  Has anyone seen them available as a "certified used" model?  I'm ok with purchasing a used generator so long as I know it's been maintained and thoroughly checked out by a reputable, experienced mechanic. 

 

In my mind, it's like buying a late model used car from CarMax.  IME they're generally in good shape mechanically and can make great daily drivers.  And you don't have the massive depreciation you get as soon as you purchase a new car and drive it off the lot.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...