quote:

Originally posted by HRK:


One of the big concerns is, what happens if power companies decide they don't want to buy back power from solar, or they reduce what they pay per KWh, and states allow them to do this in 10 years, now you'll need to invest $$$ into a powerwall...

Entergy In Louisiana has already altered this from retail rate to wholesale rate when net metered

That system seems very expensive (about $2 per watt of Solar capacity, after tax incentives).

It doesn't look like it works out math wise for you.

Even a cheaper system from Tesla ($1.49/watt) providing 16.32kwh will cost about $24,200 and will cover about 65% of your power needs.

Edited: Further discussion of time value of money below.

This message has been edited. Last edited by: Aeteocles,

quote:

You'd be better off just investing your money

That's my take, the only advantage would be it's protection against rising energy costs over the next 20 years.

One day your energy bill may rival your home mortgage payment....

I was wondering if a smaller system, installed during the lower energy use times would yield enough energy credits to offset the short 3-4 months of max energy use.

Dec to May we use less than 2000 KWh per month, it's the 3000+ KWh we use July to Sept that is the killer months, we'd be over the system use during those months...



Right now we have clean cheap energy, put Biden and Harris in office and I'd bet that energy prices to consumers will rise considerably.

quote:

Originally posted by Aeteocles:

$24,200 invested in Solar returns 0 during the payback period of 8.4 years. The $240 a month savings each month after 8.4 invested at 6% over the remaining 16.67 years is $80,925.86.

You did this calculation once before and I still don't quite understand it. The initial investment occurs on the first day of the first month, but you start saving on your electric bill on the first day of the second month. Why can't you start investing the savings then?

In other words, wouldn't this be an apples to apples comparison from a cash flow standpoint?:

1. Invest $24,200 day one, spend $240 each month thereafter for 25 years.

2. Buy solar for $24,200 day one, invest $240 each month thereafter 25 years.

Trapper, sir, you appear to be correct. Yours is the more apples-to-apples comparison because I failed to take into account that a person who invests $24k on day one still must pay for power out of pocket--which, ultimately, is the same as someone who pays out of pocket for solar on day one but does not have to pay monthly for power.

$24,000 at 6% for 25 years is $103,004.90.

$24,000 in Solar means a starting investment balance of 0, but $240 a month over the next 300 months invested at 6% is $162,309.35.

So, it looks like HRK might very well be ahead about $60k over a 25 year period by going solar and paying himself the savings.

Updated numbers for my own system now looks like this:

$12,000 invested at 6% interested will be worth $51,502.45 at 25 years.

$12,000 invested into Solar will save $180 a month, which, if invested at 6% will be worth $121,732.01 at 25 years.

Man, saving a little over time really does go the distance!

quote:

Originally posted by old rugged cross:
One thing that many do not consider is when on the grid. You just pay and receive. That is basically it.

The system you embarked on is a maintenance headache in the making and it is all yours.
Now Tesla might stand behind it, for a while or maybe not. And who knows, it might never need anything, lol. But that is not how they work.

I just do not see the benefit. But you do. And in this case that is all that matters. I do not wish problems for you. I know you research things well. So it will probably work out ok.

You pay and receive until you don’t. The ranch is served by PG&E. A 12KV three phase line enters the ranch and serves the front gate, the barn, and the three wells. The house is off grid solar. On more than one occasion we have learned that PG&E had issues when we got to the front gate and it didn’t open.
Yes, solar takes maintenance. So does septic, wells, and water systems. There is something to be said for having control of your own maintenance.

Also, during a recent wildfire, one of the hundred plus year old sycamores fell and took out the 12KV line. No power to the barn, gate, or wells. Thankfully we had a bit over 200,000 gallons in the tank, so there was plenty of water. Thankfully the house was off-grid solar so we had no issues with running up to the house for a bite.

Being responsible for your own power, water, and septic is more work, but you can set things up to be pretty darned reliable and you are not subject to someone else’s priorities.

ETA:

quote:

Originally posted by old rugged cross:
Understand K, I might be wrong. But I feel the grid is as or more so reliable than a stand alone solar system.

That has not been my experience in fifteen years of living in a house powered by off grid solar. Heck, there was a period a couple years ago when PG&E Troublemen were out two to three times a week to replace fuses on the 12KV lines after turkeys flew into the lines. Let’s just say that I was on a first name basis with three of the four troublemen in this area and got to know Troy, Todd, and Mario really well.

quote:

Lets say there is an earthquake. I doubt a personal solar system is going to be any better or worse off than the grid.

I’d be shocked if our personal solar system isn’t *much* better off than the grid in an earthquake. No trees big enough to cause a problem nearby. No wires running above ground on poles. Panels on a metal building (garage), inverters and charge controllers on backboard in the garage, batteries in stout battery shed immediately beside the garage, very solidly racked, propane powered backup generator on slab, under roof, immediately behind garage. If the big one hit, I’d worry
A whole lot more about the 400,000 gallon water tank.

quote:

Originally posted by Aeteocles:
Updated numbers for my own system now looks like this:

$12,000 invested at 6% interested will be worth $51,502.45 at 25 years.

$12,000 invested into Solar will save $180 a month, which, if invested at 6% will be worth $121,732.01 at 25 years.

Man, saving a little over time really does go the distance!

I have been saving a few thousand per year since the switch was turned on, on my array. I leased, and did it for $ reasons only. Power has been going up here so every time it does I save even more money. Daily driving electric (I drive the truck on the weekends) I'm doubling down on the array saving even more money.

Trick here is choosing the right power plan. WE don't have net metering in my state (oil state). I'm on a plan that charges me and pays me for my power, the same kwh rate. Bill for July was $29. With my solar lease payment that's $129 all in. When I was grid only, I'd pay $300 for July.

quote:

Originally posted by offgrid:

quote:

Originally posted by jimmy123x:

And in addition, the batteries have a short life compared to the system. 5-7 years, generally.

We've been offgrid (solar/wind) for over 15yrs with our original batteries. Batteries are Unigy II AGM.

Ditto, except solar with propane powered backup generator and Rolls 1700 amp hour 2 volt batteries, 24 in series to make a 48V nominal DC bank.

Batteries are still going strong after fifteen years though the monthly top off with distilled water doesn’t always happen. Other than that, the only maintenance has been applying a little noalox with a paint brush to any corrosion showing up on the connections, and maybe two or three times in those fifteen years, blowing the tops of the batteries off with compressed air as the ranch can be rather dusty sometimes.

Probably should investigate wind as the coastal breeze is very consistent, but solar has taken care of things well enough I haven’t bothered to do the research.

Battery packs are $8K each, probably need 2 to run the fans, fridge, lights, tv, basic 110 stuff, have to switch off all 220.

For a better comparison to Tesla, asked him for a quote on a 16KWh system.

If we install 16 KW, that will be enough to offset 78% of your bill.

Here is an estimate for 16.12kW:

Total price before credit - $43,524
26% Tax Credit - $11,316
Price after tax credit - $32,208

20 years at 2.99%:
first 18 months - $182 /month. After that your payment will go up to $248 if no 26% paydown by month 18.

It will produce over 22,434 kwh/year, which is 78.22% offset.

Tesla is as follows

16.32 kW Solar Panels $32,800
Cash price $32,800
Federal Tax Credit-$8,528
Price after incentives $24,272

Again it's about 78% coverage so we'd still have a power bill. The Net being if you paid monthly, which gives you the real comparison of current power costs to solar is a $87 a month reduction.

Solar would be $165
Duke Energy $158
Net savings $87


Tesla is less expensive for a 16.32 kW system at $24K to $32 locally. pretty significant difference....

Too bad Tesla doesn't have a 20 kW system

$87 a month seems like a pretty good chunk in savings.

quote:

Originally posted by Aeteocles:
$87 a month seems like a pretty good chunk in savings.

True, I've contacted Tesla, to see if they offer a 20kW system, and the financial details, since they are less on the 16kW, a 20 will do 100%.

Now mind you it's not 100% every month, that's the total annual projected kW use being 100% covered, the output of the system will not cover the bill in several months, but the net net net at the end of the year is zero.

You never truly get a zero cash flow position, unless you overbuild the system, which only makes sense if you are in an area where you can sell your excess credits to third parties.

It's important to know the state incentives, national, and what you can and can't do.

Right now it appears if I go over 10kW system in FL I have to up my Liability to a Million on the HO policy, not sure what that increase will be per year, another way you pay to play.. FL Law.. ANd there may be some kind of additional permit fees required for a larger system.

Seems the more I look the more I find.

I just received a quote today from a local solar company for a 15.2kW and 4 Powerwalls........ $90k (pre-incentives)..... they crazy

So, I wanted to a quote for Tesla. Seems like they don't really do quotes and options and such. You only provide your address and average electricity bill and they spit back a dollar number. Nothing to discuss? That's it?

After that, it seems like you either click to initiate the purchase or close the window. That's the extent of the quote process. I guess they just give you what ever they want. No choice in panel vendor or anything else?

I understand this is good for them - streamlines operations and inventory. Keeps it all simple. But I guess we're supposed to trust that they are using good components and such? And how do we find out about TCO - what costs should I expect after install for the life of the product?

I'm a little uncomfortable with this "you gotta buy it to find out details" approach.... Sounds vaguely familiar w/o good result.

quote:

Originally posted by snwghst:
I just received a quote today from a local solar company for a 15.2kW and 4 Powerwalls........ $90k (pre-incentives)..... they crazy

You can buy a 15 kw built in generator and a lifetime of fuel, electricity, and maintenance for less than that!!!!!

quote:

Originally posted by konata88:
So, I wanted to a quote for Tesla. Seems like they don't really do quotes and options and such. You only provide your address and average electricity bill and they spit back a dollar number. Nothing to discuss? That's it?

After that, it seems like you either click to initiate the purchase or close the window. That's the extent of the quote process. I guess they just give you what ever they want. No choice in panel vendor or anything else?

I understand this is good for them - streamlines operations and inventory. Keeps it all simple. But I guess we're supposed to trust that they are using good components and such? And how do we find out about TCO - what costs should I expect after install for the life of the product?

I'm a little uncomfortable with this "you gotta buy it to find out details" approach.... Sounds vaguely familiar w/o good result.

Yeah, no quotes or options and such. They sell their panels in 4/8/12/16 kwh increments, and the cost is similar across the board: $1.49 per watt, after incentives. The online portal just sizes your system based on your usage.

After you hit order, you take a bunch of pictures of your electrical panel and upload it to the Tesla website. After a few days, they spit out a design proposal and make an appointment for a pre-installation walk through.

My walkthrough is tomorrow. My proposal indicates that I'm getting Solar Edge inverters, and Hanwha Q.Peak Duo G6 panels.

Tesla is standing behind the installation and if the panels go south, Tesla will handle the manufacturer warranty for me. Labor and workmanship is warranted by Tesla. I understand that, for the price, I am getting a mass market product. It's not a car or a fine watch, it's an appliance that spits out electricity and is being installed by a company that has so much money that replacing my panels 5 or 6 times throughout it's life would be a minor inconvenience.

Thanks for all the insights Aeteocles. Very useful.

The proposal outlines all the details like manufacturer of various key components like inverters and panels? That's good. I'm not sure what the key components are. Probably not many components, just a few big ones and then mostly later and government stuff. Once you know the details of the proposal, can you negotiate some changes (not sure I want to / need to; I don't know what to request at this point anyway - I just in general don't like the feeling of a big expenditure w/o knowing what I'm getting). And if they have a 'bumper-bumper' warranty for 25 years, that's makes it a little less concerning (although still not clear on TCO - what am I expected to fix out of pocket vs them?).


One key aspect is safety - I assume sufficient quality for both parts and labor are used here such that I don't have to worry about fires and such. I haven't heard of this being an issue w/ solar panels but don't want to burn my house down to save a few thousand dollars.

One open for me is whether to lease or buy. I think it depends on how fast prices will continue to come down and/or how much better the technology will improve. And the terms of the lease (ie - can i limit to 5 years). Purchase is the default at this point though (given reasonable costs).

quote:

Originally posted by Aeteocles:
Updated numbers for my own system now looks like this:

$12,000 invested at 6% interested will be worth $51,502.45 at 25 years.

$12,000 invested into Solar will save $180 a month, which, if invested at 6% will be worth $121,732.01 at 25 years.

Man, saving a little over time really does go the distance!

You fail to account for the fact that there is no way in hell the batteries are going to last anywhere near 25 years long.

quote:

Originally posted by jimmy123x:
You fail to account for the fact that there is no way in hell the batteries are going to last anywhere near 25 years long.

What batteries are you referring to?

quote:

Originally posted by 9mmepiphany:

quote:

Originally posted by jimmy123x:
You fail to account for the fact that there is no way in hell the batteries are going to last anywhere near 25 years long.

What batteries are you referring to?

A Tesla powerwall is a battery.

"The Tesla Powerwall comes with a 10-year warranty guaranteeing the battery will retain 70% of its original capacity by the end of the 10 years. Like all batteries, the capacity will deteriorate over time. The rate of deterioration depends partly on the amount of use, and the battery could even last you more than 10 entire years."

https://www.altenergyse.com/ou...ces/tesla-powerwall/