Hi from Northern California SF Bay Area

[Ampster]

I forgot about the EV, which makes solar an even better investment.

[oneand0]

My past PG&E 12 months of bills show 4,571 kWh and $1645 in payments. The Tesla offer is for them to install a 7.9kWh system, monthly payment, no long term contract, support included for $130 a month ( $1560 yearly ). It says it should generate between 10,640 - 14212 kWh a year, which is much more than I need for my home usage. When I introduce an EV next year and the mileage I'm used to driving, it should take care of half my driving on a bad year, up to almost all of it in a good year. Even if wasn't getting an EV it would be cheaper than what I am paying now for a years worth of electricity. At the end of 6 years I will have it removed for $1,500, which can be done at anytime if I change my mind.

[Ampster]

The OP is in San Francisco and I presume PG&E and Clean Power SF. He plans on retiring in 5 years, moving to Tahoe and renting the house. My understanding of this particular deal from Tesla is that the property owner can have the system removed for a $1,500 fee at any time. That would add $25 per month if his future tenant did not want that deal.

[foo1bar]

Situation solved! I ordered the Solar medium size rental from Tesla for $130 a month and they already got a hold of me. They asked if I would be available for an install within the next 2 weeks. That's fast! But I did the math and realized I cannot beat it.

$130/month?
That doesn't sound like "cannot beat it".
That sounds like "they're going to bend me over and have their way with me"
FWIW - if you have a mortgage, I'd refinance it first, before you install this thing that you'll have to pay for indefinitely.
I'm in the process of refinancing (rates are low at the moment) - and they immediately ask if the solar system is owned by me or leased/PPO.

Where are you in the bay area? I'm in south bay.
Who's your POCO?
*IF* it's PG&E, *maybe* $130/month is better than paying PG&E. (depends on how big of a system their "medium size" is.

[oneand0]

Situation solved! I ordered the Solar medium size rental from Tesla for $130 a month and they already got a hold of me. They asked if I would be available for an install within the next 2 weeks. That's fast! But I did the math and realized I cannot beat it. The medium size is should produce three times what I use now for kW for the home and an EV next year will use the rest of what it produces.

[J.P.M.]

I will try to remember that treatise when my current bottle of Permatex runs out in about 20 years.

Just reread the last sentence.

FWIW, this being a place to exchange/provide information, I attempt to contribute useful and correct information when I feel it's appropriate and within my area of personal experience and claimed professional competence. When doing so, it's also done with an eye not only to the post I'm responding to but also in a larger sense to others who may have some use of the information. Unless a safety issue is involved, my written spoor is provided on a FWIW basis, take it/leave it or anything in between.

I never expected you to have much use or understanding of any of it. In this case, I'm just fleshing out what I consider your anecdotally incomplete missives.

I'm out of this thread.

[bcroe]

Thanks for the above info. My own limited experience is that the standard hardware
used so successfully in cars and indoors, fails miserably outside. I do not expect
anything to last forever exposed to the elements, so then my question is, how long
is long enough?

For solar aps the rule here is 2 decades, while hoping for a bit more. While treated
wood is very cheap, it is a one time job with expectations of much of a decade. For
longer times one thing I do not want is materials that rust and hardware that freezes
solid. The basic plated hardware after an outdoor year is removed by turning the nut
until the bolt twists off. After 6 years outside, I find the 6061 struts and 18-8 hardware
are still quite serviceable. I do not expect an infinite life, but a good 2 decades looks
like a possibility, with no maintenance but allowing easy mods.

A really close look at my latest constructs reveals a lot more holes than the job
requires. That is because nearly half the struts on the latest were used on an
earlier project, then repurposed for the latest. Bruce Roe

[Ampster]

I will try to remember that treatise when my current bottle of Permatex runs out in about 20 years.

[J.P.M.]

Yes that is exactly how I currently use an anti seize compound.

I haven't been able to find Alumilastic anti seize in a couple of years. The product I use now is Permatex Anti Seize Lubricant and it contains aluminum, copper and graphite. It looks a lot like the Alumilastic that I used to use. That goop makes the joints easy to open years later. Perhaps you are confusing it with threadlocker which does make joints hard to open..

No, I'm not confused. Permatex is one of several thread lubricants used, although I believe there are more fit for purpose products for st. stl. nut/bolt systems. Another product, and IMO, a more fit for purpose product is Permaslik, made by Everlube, which contains MoS2 (Molybdenum Disulfide). Most all thread lubricants, even,10W30 motor oil have some anti-galling properties. Other specific thread lube products can rely mostly on graphite, copper or other metallic powders. All that's OK, but for st. stl. fasteners (and also to a lesser degree copper and titanium threaded joints) that don't need lubrication any more than any other bolted joint but can gall, specific anti-galling characteristics of MoS2 are usually more fit for purpose.

Note: the need for thread lubrication and the need and methods to prevent galling are two different animals. Galling is a phenomenon that's actually a form of cold, or pressure welding (and slightly but not entirely off topic, not unlike what is required to produce a good battery terminal of line joint). Lubrication reduces friction. A lubed st. stl. theaded joint can and may well gall, even when lubricated. Seen it, done it and watched the bolts cut off a off myself from an early career failure to eer. Galling is a phenomenon specific to certain metals including st. stl., copper, aluminum, or most often metals that form an oxide surface layer. Simple Lubrication alone may not stop it.

Compounds that contain molybdenum disulfide will give better protection from galling. Still, any thread goop including MoS2 compounds is a second choice measure to avoid galling, but given the real world, probably a necessary measure on st. stl. nut/bolt systems of the type sometimes used for PV assemblies. Although perhaps real world impractical, better yet are measures that tend to help avoid the creation of the galling problem in the first place, starting with material selection. Using dissimilar metals such as 304/316 stainless, or as I mentioned before, Al-Bronze nuts works well to avoid galling in the first place. After that, pre-joining mating parts and not drawing them together by drawing down the nut and so avoiding thread friction to the greatest degree possible is a good but time consuming practice. Expecting such measures will be done without adding draconian level supervision is unrealistic. Also, tightening a joint S L O W L Y if galling is possible is another good practice. There are other tricks. I appreciate that such methods are probably not practiced on PV arrays.

As for your confusion comment, after an engineering career spent mostly as a mechanical P.E., and a fair portion of that time spent egularly designing bolted connections and bolting systems for boiler and pressure vessel systems and also structural systems supporting those systems, I'm of the opinion that I'm not as confused about bolted connections, what makes a good one and how to achieve a fit for purpose, safe and serviceable joint as you may be ignorant of the mechanisms that cause galling or the methods available to deal with the problem.

Although I don't usually recommend it, Wikipedia has a pretty good primer on the subject under "galling". You might learn something instead of repeating what you read or referencing stuff that fits your often half informed ideas. It might be worth a sniff.

Take what you want of the above. Scrap the rest.

[Ampster]

Usually it's the stainless on stainless nut to bolt thread contact area that "galls" or cold welds pretty much regardless of what the nut/bolt is holding together.

Yes that is exactly how I currently use an anti seize compound.

Aluminum in contact with stainless steel is no more of a practical corrosion problem than carbon steel bolting with aluminum with respect to galvanic corrosion. The thread galling of stainless is a function of the properties of most austenitic/300 series and a few martensitic/400 series stainless steels.

Alumilastic or other sealants may prevent some moisture/dirt ingress to the joint and the threads but I'm not sure what it's advantages might be as a means to prevent thread galling. I'd also wonder if such compounds might cause problems if the joint needs to be opened and there's goop in the threads.

I haven't been able to find Alumilastic anti seize in a couple of years. The product I use now is Permatex Anti Seize Lubricant and it contains aluminum, copper and graphite. It looks a lot like the Alumilastic that I used to use. That goop makes the joints easy to open years later. Perhaps you are confusing it with threadlocker which does make joints hard to open..

[J.P.M.]

I use Alumalastic or other antisieze whenever aluminum and stainless steel are in contact.

Usually it's the stainless on stainless nut to bolt thread contact area that "galls" or cold welds pretty much regardless of what the nut/bolt is holding together. Aluminum in contact with stainless steel is no more of a practical corrosion problem than carbon steel bolting with aluminum with respect to galvanic corrosion. The thread galling of stainless is a function of the properties of most austenitic/300 series and a few martensitic/400 series stainless steels.

Alumilastic or other sealants may prevent some moisture/dirt ingress to the joint and the threads but I'm not sure what it's advantages might be as a means to prevent thread galling. I'd also wonder if such compounds might cause problems if the joint needs to be opened and there's goop in the threads.

Most stainless and aluminum already has a fair amount of natural passivation, except that some types of Aluminum may need a chromate treatment for machined surfaces such as the surface of bolt holes after machining. Anti-galling compounds like "Neverseize" and the like are sometimes used and they are better than nothing. Most such compounds - which are not primarily sealants - usually and mostly rely on the lubrication properties of something called molybdenum disulfide, particularly for its ability to reduce the exfoliation some metals such as 300 series stainless steels experience when in high pressure contact (in effect cold welding) and relative movement as in thread contact for stainless/stainless contact that results in galling and subsequent thread seizing. Such moly disulfide compounds (and some others) certainly have their place, but there are much better ways to do it. After a lot of years designing bolted connections with all sorts of materials and applications, I've learned it's usually best to avoid application of goop to threaded joints as much as possible by using material properties for material choice/selection, keeping in mind that such design solutions may not always be possible. For example, stainless bolting and aluminum bronze nuts will never seize under most any service condition. More $$ up front for the nuts and the joint may not be quite as high pressure capable for pressure retaining joints, but the threads will never seize, reapplication of goop is eliminated and the joint inspection schedule may well be reduced. The relative initial cost of Al-Bronze nuts vs. st. stl. nuts is relatively high, but the overall cost to a project is peanuts compared to the rest of the material costs, and also small compared to the long term cost and hassle of ensuring the goop is properly applied and remains viable, including the cost of maintenance and reinspection which will also be lower. Pay now or pay later.

[Ampster]

Using 6061 aluminum no anodizing is needed, so there is no problem with cuts. Not sure what the
industry does, but my arrays were built up from purchased stock. Bruce Roe

I use Alumalastic or other antisieze whenever aluminum and stainless steel are in contact.

[bcroe]

the aluminum mounting rails - well all the cuts and holes are not anodized, so they will be crudded up.

Using 6061 aluminum no anodizing is needed, so there is no problem with cuts. Not sure what the
industry does, but my arrays were built up from purchased stock. Bruce Roe

[Mike90250]

Keep the array on your rental and sell the electric to the tenant at market rates.

Taking an array apart and moving it, is a PITA. Even SS hardware gets sticky after 5 years in the weather, the aluminum mounting rails - well all the cuts and holes are not anodized, so they will be crudded up. And then you have the roof repair/resealing.

[oneand0]

I really appreciate all of the input and forgot to put in there, the primary house I'm living in now will be a rental for extra retirement income and I won't be selling it. The cabin house that I'm moving into I already own in Tahoe and it has enough clearance from trees, that the sun shines on 2/3 of the roof, on East and West. South is a no go, the way the home is built. I'm keeping track of the sun by pictures and video from now until winter. I have over 1/3 acre and can mount more panels on the property from the ground that's free from tree shadows.

Seems I got a mixture of not worth it to move a system, to worth it, if it's DIY. I am confident about the DIY portion of it. I would never pay to put on, take off and put on. Maybe if I am tuckered out pay to put on, on the final move of the system onto the roof of the cabin home.

While I am still working and traveling to the cabin once a month, I am averaging 20,000 miles a year and thats a lot of $$ on gas. Alone I average $3900 a year in gas, and x 5 years is $19500. That's when I realized there is no way my next vehicle will be gasoline. So as of now I will read up and price systems for Grid with the opportunity to go batteries. I'm really liking what I read about the Sol-Ark 8K and I haven't got a clue what brand of panels. I know with the future EV and current monthly electric bill consumption the panel array should be about 8kw at the least.

Thank you again for all of your input. I have time to read up and think about this. If I pull the plug on a system, I want it built by end of next year to take the 26% Federal Credit.