# Solar or natural gas/propane generator?



## turfnsurf (Apr 29, 2020)

I am hoping that sharper minds can help me refine my thinking on which option would be preferable. There's a lot that I don't know, so there may be things that I should consider that I am not informed enough to be aware of. Below are things that I am aware of.

1. My home will be in Texas and will get full sun.
2. Due to Texas' recent electrical grid outages, my goal is to have as much available power as necessary. What I am unresolved on is how much power I should want my generator option to be able to provide in the event of an outage.
3. Power output - having available power for as long as possible during an outage is most important to me. I do want to be reasonable with this knowing that a generator would cease to be relevant during an extinction level event or true global catastrophe wouldn't matter. So I am trying to be measured in my expectations on this.
4. Rebate considerations or net metering options (for solar) won't determine my option, but I want it to factor into the decision due to overall cost considerations and the fact that this should be an emergency use case situation.


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## Katodude (Apr 22, 2021)

So an interesting question. But maybe the wrong one. Solar power is a source of energy for your house. It may be enough for the whole house or just supplement the grid. Of course with a big enough solar system with a battery backup you also get backup from the grid failure.

A generator is a backup device that is to be used in times of an outage. Generally going to be a cheaper option for install.

Next question, do you have an underground propane tank or natural gas piped to your house?


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## ABC123 (Jul 14, 2017)

If it were me I'd use a natural gas generator. Much more affordable and less things to have issues with down the road.


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## turfnsurf (Apr 29, 2020)

Katodude said:


> So an interesting question. But maybe the wrong one. Solar power is a source of energy for your house. It may be enough for the whole house or just supplement the grid.


Do you know what process needs to be taken to determine if the solar option would power the whole house or just be a supplement? With the fuel source being "free", would this make solar better? I am trying to sort through the pros and cons.



> Of course with a big enough solar system with a battery backup you also get backup from the grid failure.


Under this setup, would the thinking be that the solar would complement the electrical grid, and then in the event of a grid failure, the solar would take completely over? If I have the scenario wrong, can you outline what the scenario would look like?



> Next question, do you have an underground propane tank or natural gas piped to your house?


My home is piped for natural gas. I will need to confirm with the builder about propane.


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## turfnsurf (Apr 29, 2020)

ABC123 said:


> If it were me I'd use a natural gas generator. Much more affordable and less things to have issues with down the road.


Are you thinking along the lines of sensor failure and needing support? Or are you thinking about something else?


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## BobLovesGrass (Jun 13, 2020)

Batteries to make solar a real backup are expensive and space consuming, and to FULLY power a house would be very large system both solar and the battery system

If you want seamless backup a generator is the ticket.

If you are ok with limited backup, like lights, and fridge solar with batteries can be a good choice.

City or well water? If a well you likely need 240volt for that with a big initial demand at startup.


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## turfnsurf (Apr 29, 2020)

BobLovesGrass said:


> Batteries to make solar a real backup are expensive and space consuming, and to FULLY power a house would be very large system both solar and the battery system
> 
> If you want seamless backup a generator is the ticket.
> 
> ...


I have city water.

I was going to look into Costco's partner, SunRun. I believe they put solar panels throughout your whole roof. I was also thinking about Tesla's Powerwall.

I think the generator might be my preferred way. How do I determine the size for my house? I am unresolved if I want a full backup or just essentials, but either way, someone told me to 'size my panels' but I don't know what that means. I tried googling it, but I still wasn't totally clear about how to identify my needs.


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## Katodude (Apr 22, 2021)

Ok, if you have natural gas then you dont need propane, its a one or the other type thing. Natural gas is better since the supply is constant (and underground) and also cheaper than propane. So depending on what you want to spend you can go from as little about about $2-$3K for a portable generator that could power most of your house (air conditioning is the big gotcha). Or, you can buy a full standby whole home generator. They will run from about $10-$40K depending on size and permitting. A generator is probably your best option for standby power. For the full zombie apocalypse you will probably still be out of luck as the natural gas will probably stop flowing.

Solar is a different animal. Depending on the size of your house and roof square footage you may or may not be able to power the whole house with solar. This is where the sizing exercise comes in.

You will also need a battery backup to solar for two reasons. One is to have power when the sun is not shining, and the other is to be able to use your solar when there is a power failure. How much battery is also important because battery back up is expensive. Or just buy one of the new F150 where you will pay the same price for the battery and get a free truck. With grid tied solar in order to use it when there is a power failure you have to disconnect from the grid and in order to do that effectively you need a battery backup.

Solar will most likely cost you a lot more than a standby generator, but you are making a life choice. In theory it will pay for itself over time with the cost savings in electricity. Also your solar will survive the zombie apocalypse.


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## BobLovesGrass (Jun 13, 2020)

A single Tesla powerwall doesn't supply much power, 7kw peak 5kw steady if temps are agreeable.
5kw is 21 amps at 240volts.
Powerwall capacity is 13.5 kwh so they can't sustain max continuous load for even 3 hours.

Now go look at you breaker box, how big is your AC circuit alone?
Now consider lights, fridge, vampire drain of dozens of items..........
I am not trying to crap on Tesla, I own a older rwd Model S, love it. Just want you to understand what a powerwall can do, and to backup a house at near normal use bet you need at least 4 $$$$$$$$$$


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## Katodude (Apr 22, 2021)

4 Powerwalls will cost you about $34,000. Buy the new F150 for just a little bit more, and you get about 5 Powerwalls of power and they throw in a truck for free.


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## Amoo316 (Jul 8, 2021)

I think your number 3 requirement and the fact you already have gas means the gas generator is the correct answer based on your requirements. With Solar power you can power your house for a finite amount of time based on your available stored solar energy and your ability to regenerate it.

With a gas generator if you have gas, you have power, end of story. The burden stays on you to ensure your lights stay on.

If I was looking I wouldn't mind a solution that involves both in some form, but based on wanting power in case of upcoming electric grid issues/storms...etc, I think gas is the easy answer here.

You can always add solar in later to be used on a daily basis to help supplement your grid consumption plus augment a generator solution, but I'd got gas here and honestly not think very hard about it.


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## turfnsurf (Apr 29, 2020)

Katodude said:


> So depending on what you want to spend you can go from as little about about $2-$3K for a portable generator that could power most of your house (air conditioning is the big gotcha). Or, you can buy a full standby whole home generator. They will run from about $10-$40K depending on size and permitting.


A few questions.

1. Why is the A/C a big gotcha? 
2. How do you determine how much output that you generator needs to be? I read about needing to size my panel, but I am not sure how to do that. 
3. Is the _only_ benefit to the whole home generator that it _absolutely_ powers everything? 
Just wanted to confirm if this is the only benefit to people paying _at least_ $7,000 more for this type of generator when the portable would probably be just fine.



> How much battery is also important because battery back up is expensive.


I understand that property size and roof size drives how much solar power is available. Is there criteria that determines how much battery back up is necessary?


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## Katodude (Apr 22, 2021)

1. If you live in a hot climate A/C takes a lot of power, probably your largest power consumer. In a big house you can have multiple A/C units. 
2. You can probably get this from your power bill. If you have an electronic meter, you can get your daily power consumption. This will help you determine how much power you need. 
3. Its a balance. You can get solar where you can derive 100% of you power that way. You can get a generator that powers all your house or some percentage. Its all about what do you want the final result to be and how much do you want to pay.

Other advantage to the whole home generator over a portable one is they are permanently installed and ready to go on a moments notice. Many of them will switch on automatically when the power goes out. They usually have longer and better duty cycles. As in a lot of things you get what you pay for.

Here is what I did. I bought a 10KW running (12.5 peak) portable dual fuel generator from Lowes a couple of years ago when they had a sale. it cost me about $1100. I had an electrician put a bypass in my house for about $900. For about $150 I bought a propane hose that would reach the riser to my BBQ. It sits in my garage.

When the power goes out, I have to wheel it out to the hookup. Attach the power cord. Attach the propane hose, and hook it up to my riser. Flip the switches to generator mode at my panel. Start up the generator. This will run everything in my house except the A/C units (I have 2). I am pretty sure (not tested yet) that is will run the smaller A/C unit which powers the side of the house our bedroom is on. But to do that I will have to disconnect power to most of my appliances. Its a bit of a balancing act. I also have a window A/C unit in the garage which does not use much power and can install that in a guest bedroom.

So for less than $2500 I have a back up plan for a hurricane based power failure (pretty much the only type we have in Florida). I will have lights and food and be able to sleep in a not very hot room. I know what its limitations are. I know I have enough fuel in my propane tank to probably last a week. I can also use gas but I would prefer not to (although reading all the mower threads I feel more comfortable about cleaning out a carb than I once did). I do have about 4 - 5 gallon gas jugs.

At some point in the next 10 years I will have to change my roof. When that happens I will most likely be installing solar. I am hoping the technology will continue to improve and costs continue to come down (GAF has announced a solar shingle that looks interesting). I will buy as much solar as possible to run as much of the house as possible (potentially over provisioning the house as well). My next car will be an electric car that will get charged by this roof.

I suggest you start google generator and solar and do a lot of reading before you make an decisions. Decide on what your goals are and what your budget is and figure something out. Somewhere out there is a compromise answer for your. The compromise is always dollars based.


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## bosox_5 (Jun 20, 2018)

Typically solar power that goes back to the grid will not be available to your house when there is an outage (that is the case at my house).

As for a portable vs full time standby it is a question of budget and how much work you want to put in when the power goes out. If you want everything to just turn on automatically and not worry about anything except maybe an oil change every year, then a full time standby is the way to go (and all the costs, permits, and the different certified trades that need to be involved with the install).

I personally went with a 12kw (peak) standby duel fuel generator. I still needed a licensed electrician and the appropriate permits for him to come and wire and 50amp outlet outside my house and and interlock kit on my main electric panel. I also had my propane company come out and add a quick connect hook up to my buried 1000 gallon tank. Like @Katodude said above, I have to drag the thing out and hook it up (then select what circuits I want to use) but my total cost was about $2.5k instead of over $10k for the full standby.

Look at this thread for more info. It is has good info on portable generators and different set ups.
https://thelawnforum.com/viewtopic.php?p=442828#p442828


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## MasterMech (Sep 24, 2017)

turfnsurf said:


> I am hoping that sharper minds can help me refine my thinking on which option would be preferable. There's a lot that I don't know, so there may be things that I should consider that I am not informed enough to be aware of. Below are things that I am aware of.
> 
> 1. My home will be in Texas and will get full sun.
> 2. Due to Texas' recent electrical grid outages, my goal is to have as much available power as necessary. What I am unresolved on is how much power I should want my generator option to be able to provide in the event of an outage.
> ...


For emergency use only, and if you are unsure of how long you will stay in this one house, I'd setup the house with a manual transfer switch and a 50 amp twist-lock receptacle to connect a portable generator. You get to decide what size generator you want to purchase based on your emergency power needs and if your mind/needs change, you only need replace the generator and perhaps the connecting cord. The generator is also available for recreational use (RV/Camping) should you be involved in those activities. You choose the fuel for the generator as well. Gas is easy, but has storage concerns. Natural Gas is abundant and convenient but not portable. There are dual-fuel generators that can be run on gasoline or natural gas and change over quickly. If considering running either a stationary or portable generator on natural gas, you may need to have your meter up-sized.

For true SHTF scenarios, diesel is probably the best answer as it's the only fuel source that's readily available (with civilization intact), has home-brew alternatives, and has a long shelf life.

If you've got the bucks, I like the idea of a solar array combined with an EV as the storage. Even if the solar array isn't normally available during an outage, for SHTF scenarios, having all the hardware in place and a plan to make it available in the event grid power isn't coming back anytime soon seems pretty viable. Only caveat is if the EV leaves home, so does your nighttime/backup power.


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## SWB (Sep 22, 2018)

Our home had a manual transfer switch already when we punched it 15 years ago. We debated buying a smaller portable generator for emergencies but in the end decided to go the whole house generator route. Like everything else these days they're expensive but at least for us it was money well spent.


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## frekwentflier (Oct 27, 2020)

I've started looking into this as well. One thing I haven't seen anybody mention is that if the disaster is enough to knock out the electricity, it may knock out natural gas delivery as well. I would think that the natural gas companies would need electricity to run. Maybe they have generator backups? I'd find out before making a decision.

As somebody mentioned, many solar installations don't power your home at all. They just send electricity back to the grid, and then your house runs off the same grid. So you could have tens of thousands of dollars of panels on your roof and when the power goes out, you'd have no power just like everybody else. You'll need a battery backup to alleviate this, and make sure it's wired so that the batteries are charged *before* the power goes to the grid.

As for determining how large of a generator/solar panel system you'd need, you should be able to figure that out from your electric company's website or bill. My electric company provides a website that lets me see our usage down to the hour. At the very least your bill should show you your monthly usage, which you could divide by 30 and get an estimate of daily usage.

One other thing to remember, the goal may not be have enough backup electricity to live "normally" during an emergency, but rather to live barely comfortably. IE, you don't have to pay all the money to buy an expensive system when you can get by with a system that provides say half of your normal daily usage.


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## Cheesetoast (May 1, 2018)

I can run my A/C off of a 10k portable generator using this soft start. https://www.micro-air.com/products_easystart_368_softstarter_microair.cfm


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