Off-Grid Solar versus Grid cost comparison.......

[Vladimir]

I have 30 panels on five pole mounts.  Each panel is 80 watts.  So that is 2400 watts.  They are all 25 years old.

The inverter is a Trace 2024 with a Bogart Engineering charge controller (that give you a clue on age).  

The batteries have been replaced once and now need to be replaced again.  They are Trojan 8D AGM's.  They are 800-1200 dollars per battery IF you can find them.  I have eight of them.

There is a very OLD Cummins generator that is set on auto-start.  When the battery voltage hits a trigger point it runs to recharge the batteries automatically.

Here is a cost comparison of the two homes I own....

Just got my yearly electrical use summary from my ALL-Electric house. No solar panels.

Total Kilowatts Used.............................24,703

Annual Cost of Electricity......................$575.58
Washington taxes on public power.........$160.02

Total cost of Electricity for the entire year.........$735.60.

My vacation rental solar home....annual cost.

Firewood.......................................... ......$500
Propane..heat, generator, fridge, etc........$1850
Solar system repairs................................$150
Firewood system repairs & maintenance.....$250.

Total annual cost of operating the house..............$2750
 

Replacement fund for solar system (annual cost) $2000

The all-electric house is 2400 square feet and occupied year-round.
The solar house is 1800 square feet and occupied for about 100 days a year. I suspect living there full-time would probably add maybe another 2000 dollars primarily for propane.


The homes are 10 miles apart with the off-grid house being 2000 feet higher in elevation.




The total cost for all electric is $735.60 versus $4,750 for the off-grid home. $6,750 for fulltime living at the second home.

[Randyretired]

That system has probably served you well.  There are some newer products available today and the cost for things like panels have come down.  When I bought my first solar panel for my RV in 1988 the cost per watt was very high.  I have been using used panels lately that cost pennies on the dollar compared to then.  The higher voltage panels and charge controllers capable of handling that voltage greatly decreases wire cost.  Lithium batteries are often used now.  While still expensive these last a little longer and more of the capacity can be used.  Lithium batteries are less sensitive to SOC and are more efficient.   Most of the Off Grid systems use 48v now. 

We have 2,000 watts of solar on our 5er and when we are at our mountain property we plug into another 1,700 watts for a total of 3,700 watts.  We will have 1400 ah at 12v of lithium batteries when I finish adding the new batteries.  I assemble the batteries from cells to save. 

For our new place we are planning on a 20,000 watt solar array and 46,000 watts of battery storage.  It will also have solar hotwater infloor heat with propane backup. 

[hemsteadc]

You won't replace with Li batteries?  Used to live in Ephrata and enjoyed those very low power rates.

Edited January 16, 2022 by hemsteadc

[Kirk W]

9 minutes ago, hemsteadc said:

Used to live in Ephrata

In the state of WA, PA, or............. ?

[hemsteadc]

21 minutes ago, Kirk W said:

In the state of WA, PA, or............. ?

Vlad knows.  WA

 

[Vladimir]

54 minutes ago, hemsteadc said:

You won't replace with Li batteries?  Used to live in Ephrata and enjoyed those very low power rates.

They have gone up.  Douglas County is at 2.3 cents,  Chelan at 2.7, and Grant way up there 5.64 cents.  All of them are planning rate hikes in the future.  The goal for all PUD's is to reduce debt load.  That is what the county residents wanted for Chelan.  I think will be soon at 3.0 cents.

Li batteries have real issues with charging in cold weather that is below 32 degrees.   I was charging my lithium battery operated dog collar in my unheated trailer and it just stopped charging at that point.  

RV did clue me into these batteries.  https://azimuthsolar.ca/product-category/batteries/sio2/

Made in Canada and do not care about cold.  They heavier than Lithium, but for residential application they are fine.  I have only found them to be available in Canada.  Not a problem for me since it is a short drive to the border, but it appears that they haven't made much penetration south of border for some reason.  Hopefully, not reliability.

I don't know anything about them.  But they sound good, and right now I am leaning towards installing these in my current system.

I am stuck between spending a LOT of MONEY buying new stuff and continuing to replace stuff as it wears out.  $50,000 for a new system is a lot of money. 

Throwing $10,000 for batteries every five years might be a better deal until there is a break through in either technological batteries or panels.  I have waited 25 years  I guess I can wait under decade or so.

[hemsteadc]

1 hour ago, Vladimir said:

Li batteries have real issues with charging in cold weather that is below 32 degrees

So you wouldn't consider any kind of heating for them?  

[Vladimir]

I would have to build a new structure for heating. 

Then I spend money for the propane to heat the space as opposed to propane to charge the batteries. Not sure I would be gaining that much in the end, for the three months of cold weather.  That is why the Canadian batteries were attractive to me.  Plus they are a DROP IN replacement.  All I have to do is change the charging parameters in the inverter.

The other issue with Lithium was that the capacity is LESS than I thought.  Because of the ability of Lithium to discharge almost totally, I discovered that the Lithium for 10,000 and AGM for 10,000 was a push when it came to amp-hours.

I do like how quickly they charge and the fact you don't have to taper a charge.

Going from liquid lead acid to AGM lead acid was huge.  My shirts no longer have holes in them and I just don't fuss or muss with them.  That was a technological innovation that I appreciated.

[RV_]

Vlad,

While it is expensive for what I am getting, for twice? you tell me For the wattage you have now it is much cheaper installed than the other companies I just got quotes from.

9.60 kW Solar Panels

$20,160

1 Powerwall Battery

$10,500

Cash Price

$30,660

Federal Tax Credit

-$7,772

Colorado Springs Solar Rebate

-$768

Price After Potential Incentives

$22,120

Excluding sales tax and including installation

https://www.tesla.com/energy/design

You can't buy a Powerwall alone at the moment, but when it is connected to solar it heats itself. If the house is not rented out or used much when it is the coldest then the Powerwall might be able to heat itself just fine but I am just starting out. It is called preconditioning with the Powerwall II:

"Preconditioning

When temperatures are low, all batteries have a reduced ability to charge. To help Powerwall counteract this, Powerwall uses Preconditioning. When temperatures are below freezing, Preconditioning turns on and heats your Powerwall to improve operation and charging performance. To heat itself, Powerwall draws a small amount of energy, which then allows high-power charging.

During a cold night, your Powerwall automatically preheats before sunrise so that maximum solar energy can be captured during the day. Preconditioning, in combination with Tesla’s unique liquid thermal management system, allows your Powerwall to operate at lower temperatures than any other home battery."

If you have not checked Powerwall features and specs since the Powerwall II came out this page also covers a lot more.

https://www.tesla.com/support/energy/powerwall/mobile-app/powerwall-modes

I think the $50k is for three times the kWh based on your previous posts than what you have now, but I may not have apple to apple specs from you. If you configure a Tesla system it may end up cheaper than you realize for the same size system. I want to charge two EVs and run my house when not charging the cars. And as with all batteries we have to consider replacement costs in 10-20 years depending on if they still have the percent left we need. I am close enough to get delivery info as of now because they may be shipping again as bundles with panels.

I know you know everything about off grid and I don't do that. As well I am paying for installation and a warranty so seeing as how Tesla is actually more capacity than the Generac battery systems and I would have to find installers, not ones Tesla is responsible for warranting, more capacity and cheaper for top shelf panels and Powerwalls installed and Powerwalls. I a talking 19.20 kW of solar panels and three Powerwalls for $42,227. Learned with my Natural gas generators it is cheaper to get the capacity up front and pay double than to buy one system and have to buy a whole new system.

Yes I know you can install your own and add panels to the old system you have. From the wild number of $150k for a 5kW solar system as you said earlier you might need to actually look again today. It sounds like you have it covered and $47k isn't pocket change but for me worth it. Except for 18 below Feb 2021 freeze, we rarely get below 0 here in the Springs and with the Powerwalls inside the garage walls where, though unheated, it does not get below freezing. You don't have any heat on in winter or little I would guess from what you posted.

Best of luck with your upgrade. Really.

 

Edited January 19, 2022 by RV_