Gut check - am I crazy?

[Shinzul]

Hey all,

I'm about to pull the trigger on purchasing $37,859 worth of solar equipment for a whole system consisting of:
60kWh battery storage
24kw of panels
3 inverters
etc (all the other things)

The intent is for a fully off-grid large cabin in the woods (new construction). I've done the math with all the electricity usage and this should give 1 full day of autonomy.

The ROI/break-even point for this system (after US tax credit) is ~9 years, but I'm mainly optimizing for a fully off-grid capable place to live for years and years.

Am I crazy to go for this rather than connect to the grid?

 

[TomC4306]

What is the cost to connect to the grid?

 

[Shinzul]

What is the cost to connect to the grid?

At least ~$6,000 upfront, plus the ongoing annual energy cost

 

[TomC4306]

You don't have to use it. But it would be nice to have available. At $6,000 though, I'd have to think hard about that.
To be clear, I'm suggesting do both.

 

[Ampster]

I figured that, based on amortizing the cost of my solar panels over the kwh I was expecting from them that my cost was $.08-10 per kWh. The cost of storing some of that energy for use at night was $015-.020 per kWh. You can do the math based on your consumption to compare that to the cost of a grid connection. my system came in less expensively than yours but you have a lot more capacity than I have on my system.

 

[Risky Rob]

I am connected to the grid, and have a smaller off-grid backup system. The US is entering a recession, so I'm being careful; keeping cash reserves and not going into debt.

 

[Solar Guppy]

Hey all,

I'm about to pull the trigger on purchasing $37,859 worth of solar equipment

Whatever you do, only purchase listed, 1st tier products. Cheap might be ok for learning project, but not running whole home single source of power. Also are you including racking, wiring and allowance for equipment replacements or repairs costs? Also you need a backup solution as things WILL fail over the years.

Having your own whole home power plant usually isn't about saving money, its when one can't get a grid connection.

 

[OzSolar]

Not trying to talk you into or out of anything but I will mention this.

Using $18,000 for your battery cost which is just an estimate for this illustration.

5 years of useful life = 60 months = $300/month that you need to be setting aside for replacements. Hopefully that is really unlikely.
10 years = 120 months = $150/month
20 years = 240 month = $75/month

Even those companies that are still here in 5 or 10 years to support thier battery warranties will only be able to offer you a heavily prorated replacements. Has anyone actually looked at the details of thier battery's warranty? Please share.

What is your battery cost and type if you don't mind sharing?

 

[Shinzul]

Not trying to talk you into or out of anything but I will mention this.

Using $18,000 for your battery cost which is just an estimate for this illustration.

5 years of useful life = 60 months = $300/month that you need to be setting aside for replacements. Hopefully that is really unlikely.
10 years = 120 months = $150/month
20 years = 240 month = $75/month

Even those companies that are still here in 5 or 10 years to support thier battery warranties will only be able to offer you a heavily prorated replacements. Has anyone actually looked at the details of thier battery's warranty? Please share.

What is your battery cost and type if you don't mind sharing?

~17k for the batteries - 12 48v 100ah batteries. Interesting point about battery replacement over time...

 

[OzSolar]

Having your own whole home power plant usually isn't about saving money, its when one can't get a grid connection.

Bingo. Do not confuse solar with saving money, they are entirely different things. (People will be along shortly to dog pile me for that statement) From a financial only view point there are way better things to do with your money.

However if you think solar is cool and/or put a hefty price tag on being independent that's a different discussion entirely. What's the payback on a bass boat or Corvette? Nobody ever asks....

Assigning a financial value to things have 5 year or longer payback is truly foolish, especially nowadays. There's literally a million variables that can come along and crush that assumption. Google "Monte Carlo Simulation" sometime.

But if you think the world is going to end and it does end then you've got a pretty sweet payback. Of course society will have fallen and you won't be able to get this forum and wag your finger at me for being wrong.

 

[timselectric]

Having your own whole home power plant usually isn't about saving money, its when one can't get a grid connection.

For me, it's for saving money. And kicking the utility company to the curb. lol

 

[Shinzul]

Bingo. Do no confuse solar with saving money, they are entirely different things. (People will be along shortly to dog pile me for that statement) From a financial only view point there are way better things to do with your money.

However if you think solar is cool and/or put a hefty price tag on being independent that's a different discussion entirely. What's the payback on on bass boat or Corvette? Nobody ever asks....

Assigning a financial value to things have 5 year or longer payback is truly foolish, especially nowadays. There's literally a million variables that can come along and crush that assumption. Google "Monte Carlo Simulation" sometime.

But if you think the world is going to end and it does end then you've got a pretty sweet payback. Of course society will have fallen and you won't be able to get this forum and wag your finger at me for being wrong.

I think you're spot on here. Maybe this will save money over time. Maybe it won't. Other factors than money matter more, which are very hard to quantify:
- Having power available during some crazy extended historical event (however unlikely!)
- Not being tied to power company and the corruption in the US political system tied to that
- Not contributing more to killing the planet with electricity generated mainly off of coal (grrr)

 

[robby]

Bingo. Do no confuse solar with saving money, they are entirely different things. (People will be along shortly to dog pile me for that statement) From a financial only view point there are way better things to do with your money.

You must live in one of those places where power is cheap!
Most people who have Solar in the USA are doing it to save money. (Period)
Grid tie systems without batteries are all about saving money and those make up the bulk of systems sold in the USA.

My AIO system will pay for itself in six years and should last another 4-6 years after that. The money saved in those extra 4-6 Years should make the replacement system almost free. If I live long enough I might get several free upgrades over the decades. My whole system is based on kicking the utility to the Curb and using them as my Backup system.

 

[Solar Guppy]

Other factors than money matter more

Since you're over the actual cost part, build it bigger than you think you will ever need, make it code compliant with 1st tier, listed components' that would pass inspection if it were in the city / current NEC ESS codes, preferably have it engineered and installed by proven experts that you can see other work, in other words a turn-key power plant.

It will cost 2-3X what you think, but you would never regret it for years to come as it will just work.

Very few people have all the skills to take on a system like this, you may be one, but be honest with yourself and know your limits.

 

[OzSolar]

My AIO system will pay for itself in six years and should last another 4-6 years after that.

"should"

 

[Solar Guppy]

Most people who have Solar in the USA are doing it to save money. (Period)

My AIO system will pay for itself in six years and should last another 4-6 years after that.

The future of low cost gridtie is near an end, as it isn't economical to provide free storage of the grid, at a scale of more than a few percentage of the customer base uses it.

Most states are rewriting the laws, making things like minimum connection charges and or breaking out the distribution costs vs generation costs and no more free ride for gridtie. Then we have the firemen writing endless new codes without any validation or cost benefit analysis, totally unchecked ( some may not know NEC code is written by the fire protection lobby )

It maybe a good deal for those locked in, but it is not a sustainable model at scale. It was always considered discounted to jump-start the industry, that time is in the past ( IMHO of course )

 

[rmaddy]

should give 1 full day of autonomy.

Have you worked out a rational plan for when you have no solar for two days due to bad weather? What about a whole week of really poor solar conditions?

 

[Shinzul]

Have you worked out a rational plan for when you have no solar for two days due to bad weather? What about a whole week of really poor solar conditions?

Yes, a 1,000 gallon buried propane tank with standby backup generator.

 

[rmaddy]

Yes, a 1,000 gallon buried propane tank with standby backup generator.

Out of curiosity, is the propane also for everyday use for heat, hot water, and cooking? That would really cut down on your daily Wh usage.

I haven't done the math for something like a full-time cabin but I have to think propane is cheaper than a lot of LiFePO₄ batteries.

 

[Solar Guppy]

Yes, a 1,000 gallon buried propane tank with standby backup generator.

Again, that needs to be part of the design and how it is auto-failover and exercised at least monthly.

I hope your looking at a pair ( or more ) of XW-6048's or equivalent, your budget looks to small by 2-3x for the equipment you will need. Growwatt and the like are not really an option for what you're proposing