Is there any benefit to changing the date for your permission to operate?

[J.P.M.]

No apologies necessary, really. Perhaps one of the things that keeps my AC usage down is I have planted a fair amount of foliage around the house and keep it trimmed. Additionally, I installed Coolaroo window sun shades on all my south and west facing windows. Those help a lot. I ended up replacing the HVAC unit in 2016 and while not the most efficient at the time, it's much better than before (I think it's a SEER 16 rating).

I'm currently on the domestic tiered plan and I'm sure TOU will affect things going forward. Which begs the question of which TOU plan to select. Ideally a battery (like a Powerwall) would help offset some of the peak rates, but I'm not in a position to afford one of those right now,

Understood.

Kudos on lots of heads' up work on reducing A/C load.

On the Coolaroo shades: Interior or exterior ?

Not bad, but not the best news: Finding best rate plan is never an easy task. It also involves more assumptions about the future that increase the uncertainty of the analysis which is impossible to know with a lot of certainty in the first place. Still, some homework and a few hours of reading up on POCO rates/policies can yield useful information.

To do it right - that is, to do an analysis of use vs. available rates that shows as much of the information as necessary for an informed choice about which rate plane is likely to have the highest probability of the lowest cost of providing future electrical service for your chosen length of time into the future - is right up front - a PITA. A big part of the PITA is the necessity of doing a deep dive into the POCO rate policies and plans. I haven't found a way around that yet that gives as reliable results.

Take what you what of the following.

The overview:
1.) Decide what your future electrical use is likely to be to meet your future goals. Get as granular as you can. Ideal would be 15 minute increments. Such historical info is available from the POCO. Often, using such historical usage data and then adding estimates/SWAGs of possible future changes/increments to those 15 minute use numbers might improve the guesswork from SWAG to educated dart throw status. Combine the 15 minute data to 1 hour increments. You'll lose a slight amount of accuracy in doing so, but it's all an est. to begin with. Put that data on a spreadsheet.
2.) Use the PVWatts hourly output option to estimate system output. That data is all on standard time. Correct the PVWatts data for daylight savings time. Put that data on the spreadsheet making sure the hourly times line up. The spreadsheet will have 8,760 rows of hourly data, one for each hour of the year.
3.) Subtract generation from use.
4.) Multiply each hour's net draw (either + or -) by the electricity rate for that hour.
5.) Sum the net draw per billing period.

Do that for each rate plan under consideration and choose the one that suits your fancy - I'd guess the one that results in the lowest annual bill.

There may be and probably are easier ways to do it, but since I'm pretty ignorant about spreadsheets, that method, with a few additional minor points I've left out for the sake of brevity, but don't affect the outcome much, works for me. There's also a lot of repetition/copying in the spreadsheet 's creation which saves time.

[loungelizard]

Understood.

Kudos on lots of heads' up work on reducing A/C load.

On the Coolaroo shades: Interior or exterior ?

Not bad, but not the best news: Finding best rate plan is never an easy task. It also involves more assumptions about the future that increase the uncertainty of the analysis which is impossible to know with a lot of certainty in the first place. Still, some homework and a few hours of reading up on POCO rates/policies can yield useful information.

To do it right - that is, to do an analysis of use vs. available rates that shows as much of the information as necessary for an informed choice about which rate plane is likely to have the highest probability of the lowest cost of providing future electrical service for your chosen length of time into the future - is right up front - a PITA. A big part of the PITA is the necessity of doing a deep dive into the POCO rate policies and plans. I haven't found a way around that yet that gives as reliable results.

Take what you what of the following.

The overview:
1.) Decide what your future electrical use is likely to be to meet your future goals. Get as granular as you can. Ideal would be 15 minute increments. Such historical info is available from the POCO. Often, using such historical usage data and then adding estimates/SWAGs of possible future changes/increments to those 15 minute use numbers might improve the guesswork from SWAG to educated dart throw status. Combine the 15 minute data to 1 hour increments. You'll lose a slight amount of accuracy in doing so, but it's all an est. to begin with. Put that data on a spreadsheet.
2.) Use the PVWatts hourly output option to estimate system output. That data is all on standard time. Correct the PVWatts data for daylight savings time. Put that data on the spreadsheet making sure the hourly times line up. The spreadsheet will have 8,760 rows of hourly data, one for each hour of the year.
3.) Subtract generation from use.
4.) Multiply each hour's net draw (either + or -) by the electricity rate for that hour.
5.) Sum the net draw per billing period.

Do that for each rate plan under consideration and choose the one that suits your fancy - I'd guess the one that results in the lowest annual bill.

There may be and probably are easier ways to do it, but since I'm pretty ignorant about spreadsheets, that method, with a few additional minor points I've left out for the sake of brevity, but don't affect the outcome much, works for me. There's also a lot of repetition/copying in the spreadsheet 's creation which saves time.

OK, thanks for the tip on the 15 minute increments. Looks like I've got some downloading to do and then some spreadsheet work. And thanks too for the daylight savings time for PVWatts (that's a biggie here in the desert).

Oh, the Coolaroo, all exterior. 90% block in walnut color. I also added shade screen to the top of my pergolas.

And yes, the AC is huge variable for me because as I said earlier, I want to be able to lower my thermostat in the summer, but won't know what it looks like until I actually do it. Not like I'm looking to turn the house into a meat locker but still wants it cooler.

[J.P.M.]

OK, thanks for the tip on the 15 minute increments. Looks like I've got some downloading to do and then some spreadsheet work. And thanks too for the daylight savings time for PVWatts (that's a biggie here in the desert).

Oh, the Coolaroo, all exterior. 90% block in walnut color. I also added shade screen to the top of my pergolas.

And yes, the AC is huge variable for me because as I said earlier, I want to be able to lower my thermostat in the summer, but won't know what it looks like until I actually do it. Not like I'm looking to turn the house into a meat locker but still wants it cooler.

Understood. Thank you.

My solar magnum opus design I did for Borrego Springs - that went through plan check and permitted, but not built - used mini-splits for cooling. Kind of overkill for you at this point, but maybe a consideration if you have large and unused/partially used but currently cooled spaces. Just sayin'.

I had a another thought: I may have been incomplete in talking (writing) about tiered vs. T.O.U. rate plans. Strictly tiered rates are just that: No time of day dependence on the hourly rate. Just so much in the way of charges over any billing period for tier one usage, and more for tier two usage, and draconian charges for large usage above 400 % of baseline allocation.

However, T.O.U. rates often and (now, more and more) usually come with a tiered rate effectively laid over the top of the T.O.U. rates.

It usually, and for SCE, works something like this: A T.O.U. rate is published. THEN, a CREDIT per kWh is applied against the published rate for use up to the tier one usage in any one billing period. That credit/kWh then disappears for billing period usage above the baseline rate. In effect, it's a T.O.U. rate with a tiered rate laid over the top. For users with low usage, particularly in the summer, it can be helpful. Less so for users such as you with patterns of low year round total usage but what reads like high(er) summer usage.

More examples of the PITA of educating yourself about POCO rates/policies, with a lot more than usual of the devil being in the details.

[Ampster]

When designing a system I try to remember this. When you ask an Engineer if the glass is half full or half empty the Engineer will say that the glass is too big.

[SunEagle]

When designing a system I try to remember this. When you ask an Engineer if the glass is half full or half empty the Engineer will say that the glass is too big.

Or in some cases the Engineer will say just pour more concrete in the hole.

[Ampster]

In my fifty plus years in various aspects of construction, one of the biggest regrets many people have expressed is designing too small.

One only has to look at the system @bcroe built over the years to see an example of a system that not only reduced electric costs to zero but eliminated the need to consume propane. That was what I meant in an earlier post by financial hedging.

[loungelizard]

In my fifty plus years in various aspects of construction, one of the biggest regrets many people have expressed is designing too small.

One only has to look at the system @bcroe built over the years to see an example of a system that not only reduced electric costs to zero but eliminated the need to consume propane. That was what I meant in an earlier post by financial hedging.

I can understand this. In my case, if I am to oversize some, sure, I'll pay more and might even think I shouldn't have gone that high for a while. On the other hand, if I end up short when I get an EV, I'm really going to be bummed and wishing I went larger.

[J.P.M.]

When designing a system I try to remember this. When you ask an Engineer if the glass is half full or half empty the Engineer will say that the glass is too big.

You may get such responses from folks who, for whatever reason, are rude, give you a blowoff answer, and/or don't what to waste time responding to you.

I suppose a lot of lawyers might respond to that same question with :"It depends". So what ?

Believe it or not, some situations can't be adequately described in 25 words or less.

Anyway, and to my experience only, most engineered systems and decisions made about their design and use, are a bit more involved than an open top container.

[J.P.M.]

I can understand this. In my case, if I am to oversize some, sure, I'll pay more and might even think I shouldn't have gone that high for a while. On the other hand, if I end up short when I get an EV, I'm really going to be bummed and wishing I went larger.

Well, there's a lot of room between all/nothing. For system sizing, the trick is to find or get as close to the sizing sweet spot as possible. In general, more education increases the probability of getting close(r) to it.

If you're interested:
Like many others in similar situations, yours is a set of choices that leads to a system design - including STC size - that balances all the design goals you set as best as possible.
Usually, the best that's possible is a matter of settling.
The idea for system design and engineering, as I learned it anyway, was to design and install systems that are safe and fit for use and purpose.
Fit for use and purpose starts with setting goals and/or desired outcomes.
Those goals may be fixed or flexible. Either way, or more likely somewhere in between, after education about the gory details needed to meet them, the better defined the goals, the higher the probability of fit for purpose outcomes.
For most folks getting residential PV, one common, often the largest, and perhaps only goal is to reduce the overall long term cost of providing electric service to their residence.
With respect to sizing systems to meet that goal, because life is not perfect, and because that may not be the only goal, and because the future has a pretty high probability of being different than we plan, not to mention there's a lot about system design we don't know, some oversizing of a PV system is probably a good and even necessary design parameter.
Bottom line: Life is a crap shoot. Consider the cost of some oversizing an insurance premium against future uncertainty - just know the cost of the premium and what you get for it in terms of +'s/-'s.
Unfortunately, the degree to which a system is oversized will probably have the biggest negative impact on the other usual design goal of cost effectiveness.
Unfortunately or otherwise, part of good design is almost always a choice and a balance among competing design goals and priorities.
To have the best chance (highest probability) for the desired (and realistically possible, workable and attainable) mix of design goals is where the education about the gory details comes in.

Oversize too much and you'll have a higher long term cost of providing electrical service than if you had done nothing, that is, no PV will be more long term cost effective than too much oversizing.
Undersize and you'll have a lower long term cost of providing electrical service, but you won't save as much as if you hit the (always a priori unknown) sizing sweet spot.

More education about PV, solar process economics and how the POCO NEM game is run will help increase the probability of winding up with the most cost effective system size.

Your money, priorities, choices, decisions, life. And, absolutely, NOMB.

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

[Ampster]

..........For system sizing, the trick is to find or get as close to the sizing sweet spot as possible. ..

Like many others in similar situations, yours is a set of choices that leads to a system design - including STC size - that balances all the design goals you set as best as possible.
.....
Those goals may be fixed or flexible. .......
With respect to sizing systems to meet that goal, because life is not perfect, and because that may not be the only goal, and because the future has a pretty high probability of being different than we plan, not to mention there's a lot about system design we don't know, some oversizing of a PV system is probably a good and even necessary design parameter.........
Bottom line: Life is a crap shoot. Consider the cost of some oversizing an insurance premium against future uncertainty - just know the cost of the premium and what you get for it in terms of +'s/-'s..............
Your money, priorities, choices, decisions, life. And, absolutely, NOMB.
..........

My system is oversized by design but it does fit the above criteria. I have eliminated my natural gas water heating and when my AC compressor goes out I will probably replace it with a heat pump design yet to be determined. I understand the thermal efficiency tradeoffs but with the prospects of more unavoidable fixed charges for electricity it fits my decision matrix to continue to lower other energy costs as much as possible. I have a low cost of capital and can DIY solar and battery pack upgrades to accomplish my goals. I just wish I had more land so I could have a solar farm like @bcroe,

[J.P.M.]

My system is oversized by design but it does fit the above criteria. I have eliminated my natural gas water heating and when my AC compressor goes out I will probably replace it with a heat pump design yet to be determined. I understand the thermal efficiency tradeoffs but with the prospects of more unavoidable fixed charges for electricity it fits my decision matrix to continue to lower other energy costs as much as possible. I have a low cost of capital and can DIY solar and battery pack upgrades to accomplish my goals. I just wish I had more land so I could have a solar farm like @bcroe,

Nice cherry picking on my post.
Kind of off topic by jumping from cost PV cost effectiveness as f(sizing and POCO rates) to cost (in)effectiveness of using electricity as a heating source, but since you brought it up:

Every situation is different. Like you, I don't have much of a heating season. A decent heat pump operating with an achievable C.O.P. of 3.0 or so and the current nat. gas and electricity costs around here still would cost me more than using nat. gas for space heating by ~ $150-200/yr. But my situation, like yours, is anecdotal.

In a more general sense and particularly in colder climates than mine, folks find that performing simple tasks such as space or water heating that can be done with lower quality energy from sources such as nat. gas. are usually more cost effective than using low(er) entropy (and so more versatile) electricity for tasks that only it can do (such as powering the screen you're reading). For the same energy quantity, nat. gas is less expensive for a reason. The high(er) versatility of electricity is reflected in the higher cost of producing higher quality (lower entropy) energy, often, BTW by burning nat. gas from the same source as folks use in their gas fired water heaters.

Using resistance electricity for space or water heating is like cutting butter with a chain saw, particularly if lower cost nat. gas is available that uses less complicated (read more reliable) equipment. HPWR are a bit better in moderate to warm climates, but places with a serious winter can also make residential heat pump applications cost effective are most often a real challenge.

Apologies to the OP for dragging things off topic.

[Ampster]

No worries @J.P.M. I am not trying to change your mind about system sizing theory.
In post # 10 the OP asked about system size and I was giving him and future readers another perspective on how I have approached system size. My reference to the system of @bcroe is another example of an approach to system size that I have found helpful. I am glad we can agree that heat pumps are more efficient than resistive heat.

[J.P.M.]

No worries @J.P.M. I am not trying to change your mind about system sizing theory.
In post # 10 the OP asked about system size and I was giving him and future readers another perspective on how I have approached system size. My reference to the system of @bcroe is another example of an approach to system size that I have found helpful. I am glad we can agree that heat pumps are more efficient than resistive heat.

1.) I don't worry, nor do I suspect you're attempting to change my opinions, but if you present logical arguments, I'd certainly consider them and perhaps change my views in some ways.

2.) Putting aside for a moment the idea that heat pump technology is way more complicated and so have a higher probability of problems than a fired boiler for the task of providing heat, that we may agree that heat pumps are a more COST EFFECTIVE method of providing heat than resistance heat misses the point entirely.

We probably both agree that a silver ingot is a more cost effective paper weight than a gold ingot. My point about nat. gas being a better source of fuel than electricity is analogous to using a rock for a paper weight rather than either gold or silver. All 3 will work. The rock is far more cost effective than the other two materials. It also doesn't take much processing to get it in a usable form.

As for the sometimes unavailability of nat. gas: I remember a story from an undergrad. engineering teacher I had who was talking about unusual material choices and how they depend on material availability. There is (was ?) a home built in the late 19th century for a manager of a platinum mine and processing plant in Siberia. The story goes that for some reason(s), copper was hard to find/unavailable in the rather isolated area. So, the house (which was apparently substantial and the only one in the area with indoor plumbing) had all the plumbing and fixtures made of platinum. Moral: Use what you got. The cheapest fit for purpose stuff first.

That story relates to the availability/lack of availability of nat. gas in that there may be some places, maybe more than a few, where nat. gas service is unavailable: I live in one of them, and because I don't need much aux. space heat, I use propane for space heat, and solar thermal provides ~ 95+ % of my DHW load, but that's off topic even more than we are already.

Anyway, where available, the smart money usually uses electricity as the fuel of last resort unless availability or economics truly dictate otherwise. Nat. gas, while not ubiquitous, is close to it and commonly available in many/most areas of the developed world. Where it is available, and because it's use technology is well developed (read simpler) and also probably less expensive, as well as the cost of the fuel being less on a per unit of heat basis than electricity, seems to make natural gas the logical and preferred choice for heating things like homes and water for a lot, if not most applications.

Can we get back on topic now ?

[bcroe]

I would like to add a few experiences using gas, certainly your results will vary. DIY work will
likely save 60%, some technologies much better lend themselves to doing this.

If you have Air Conditioning, you are adding very little complexity to use a heat pump instead.
Using the latest technology could be quite an improvement on many fronts, again your results
will vary. I see mine as a step up in quality and reliability over previous equipment, though 2
years is a bit limited trial. With enough solar to cover AC, you might take on some heating as well.

Starting with gas, I did experience failures of the central heat. Putting in a high efficiency
furnace and water heater seemed like a good idea, beside consuming less energy, the chimney
and all the air loss up it were eliminated. But soon these units had failures. By the time the house
sold a couple decades later, I had a complete set of spare parts for both units, mostly gotten by
repairing the failed parts. The high efficiency propane stuff at this house has not done better.

The propane equipment is nearly the same as for natural gas, conversions between are simple.
But connecting up the new gas line would be costly, followed by monthly billings which are far
from zero even on the months hardly any gas is used, with both fixed and energy charges never
moving any direction but up. In recent years I have see the price of propane manipulated to cost
8 times the value of the electricity my heat pumps use, even double straight resistive heat. Clearly
my setup is quite operationally competitive with propane, if you can bear the initial investment.
Just where natural gas price falls today I do not know, but I expect it will continue to rise. Bruce Roe

[Ampster]

Back to the OPs question, the comments of @bcroe are all factors that went into my long term strategy. That strategy included some over capacity. I am fully aware of the longer rate of return and the cost of that over capacity. I view it as a financial hedge. That hedge has value to me. As with anything in life,, your mileage may vary. It all depends on where you are standing. I hope this is helpful to the OP as he formulates his decision.