1st real post, equipment comparing

**J.P.M.** · 12-05-2018, 10:54 AM

Start with ways you can reduce your load rather than talking yourself into equipment by getting all excited about it. Your annual usage is small enough that with more conservation and load reduction, you may not need or be able to make PV as long term cost effective as not doing PV.

How large are the systems being quoted to you ?

What does PVWatts model as a long term average output/year for your possible array's orientation per installed STC kW ?

Any shade ?

How much of your annual usage do you want to offset ? All, or 100% offset of usage is not necessarily as cost effective as less offset - depends on how much you use and you are billed for the power. Get familiar with rates and rate options from your POCO. That's a PITA but it will pay big dividends.

How important is reducing your bill vs. other benefits/drawbacks of getting PV ? If cost effectiveness is important, starting with load reduction will pay back much sooner than ignorantly throwing (oversized) PV at usage before use reduction.

Panels are pretty much a commodity these days, and beyond some basic quality level are about identical to one another in terms of reliability and annual output per installed STC kW.

If you have little or no shade micros or optimizers won't get you much except more components to fail. They will not restore production that was not there in the first place due to shade.

Learn how you are billed for power and how things are changing in that regard. NEM ain't what it used to be - probably ~ 20 % less cost effective than a couple of years ago.

You may be able to reduce your bills via time shifting of loads and so game the T.O.U. billing you will likely be changed over to, but PV is not as cost effective as it once was (and was always or mostly marginally cost effective even then).

Unless you have some really bizarre requirements, reliable systems can be had in CA for probably ~ $3.25 - $3.50/STC W before tax credit. Pay much more tan that and you're leaving $$ on the table. Same for oversizing only more so in terms of long term cost ineffectiveness. For Santa Maria and your usage any shade free system with good orientation that's larger than ~ 4 STC kW will produce more than your annual usage.

Vendors commonly oversize by a fair amount for what are in the end mostly but not entirely B.S. reasons.

Most everyone who oversizes a system claims to want an EV as a justification. I live in one of the EV (and PV) centrals in the U.S. I still don't see a lot of EV's driving around compared to several years ago. That excuse of "but some day I'll have an EV" looks like a red herring poor justification to get a new toy and keep up with the Jones to me. Just sayin'

Oversizing will kill PV cost effectiveness in short order.

Get a copy of "Solar Power Your Home for Dummies". It's a bit dated but still a good primer, including the parts about conservation and use reduction. ~ $25 @ bookstores/Amazon or a free online download if you root around some.

Welcome to the neighborhood.

**Ampster** · 12-05-2018, 02:39 PM

Originally posted by J.P.M.

...............

Most everyone who oversizes a system claims to want an EV as a justification. I live in one of the EV (and PV) centrals in the U.S. I still don't see a lot of EV's driving around compared to several years ago. That excuse of "but some day I'll have an EV" looks like a red herring poor justification to get a new toy and keep up with the Jones to me. Just sayin'
.........

Lots of good input in your post which I didn't quote above. The only thing I would add is be careful about the match between the inverter capacity and the system capacity. We run the system cost metric expressed as dollars per Watt of installed panel capacity. Often the inverter is undersized which results in clipping of production. It does save the installer money by using a smaller inverter.

I am an example of someone who oversized a system because I have two EVs. I am sure part of that is keeping up with the Jones, and I rarely get to drive the Tesla because my wife always gets first dibs. We have driven 60,000 miles on those cars in the past 2 1/2 years and that represents $16,000 in oil and gas that I did not have to buy. I guess the eye of the beholder sees what it already knows but I see a lot more EVs driving around compared to several years ago. Maybe my section of the state has a higher percentage.

**SunEagle** · 12-05-2018, 06:06 PM

Originally posted by Ampster

Lots of good input in your post which I didn't quote above. The only thing I would add is be careful about the match between the inverter capacity and the system capacity. We run the system cost metric expressed as dollars per Watt of installed panel capacity. Often the inverter is undersized which results in clipping of production. It does save the installer money by using a smaller inverter.

I am an example of someone who oversized a system because I have two EVs. I am sure part of that is keeping up with the Jones, and I rarely get to drive the Tesla because my wife always gets first dibs. We have driven 60,000 miles on those cars in the past 2 1/2 years and that represents $16,000 in oil and gas that I did not have to buy. I guess the eye of the beholder sees what it already knows but I see a lot more EVs driving around compared to several years ago. Maybe my section of the state has a higher percentage.

EV's are becoming more popular since the number of models and manufacturers has increased.

Still if you run the numbers some EV's will easily cost much more than $16,000 above a standard ICE vehicle price which makes it a little harder to justify going EV then ICE.

Also the price of gas around here is now about $2.11 per gallon which makes it even harder to go justify the cost of an electric vehicle.

**J.P.M.** · 12-06-2018, 01:47 AM

Originally posted by Ampster

Lots of good input in your post which I didn't quote above. The only thing I would add is be careful about the match between the inverter capacity and the system capacity. We run the system cost metric expressed as dollars per Watt of installed panel capacity. Often the inverter is undersized which results in clipping of production. It does save the installer money by using a smaller inverter.

I am an example of someone who oversized a system because I have two EVs. I am sure part of that is keeping up with the Jones, and I rarely get to drive the Tesla because my wife always gets first dibs. We have driven 60,000 miles on those cars in the past 2 1/2 years and that represents $16,000 in oil and gas that I did not have to buy. I guess the eye of the beholder sees what it already knows but I see a lot more EVs driving around compared to several years ago. Maybe my section of the state has a higher percentage.

Lots of good input is a matter of opinion and opinions vary. I only claim to have made what's probably more mistakes than most and tried to learn from them without too may repeats.

$/W of STC panel rating is pretty standard and what I and most everyone else refer to when talking price/STC Watt. There are other, different metrics for determining a system's cost effectiveness that deal with the process economics of PV processes and systems.

I'm not sure where your reference to inverter/system size came from, but inverters are not a major portion of a system cost, and anyway, increasing an inverter size to == or > system STC size won't result in too much extra expense - but still probably quite a bit more than the NPV of a fair amount of clipping.

My oil changes come to ~ $40/5,000 miles = $0.008/mile. --->>>> ~ $480/60,000 miles.

That leaves $16,000 - $480 = $15,520 for gas over 60,000 miles. If gas is going for $4.00/gal., which may be a reasonable and probably slightly conservative number for the last 2 or 3 years , you bought $15,520/($4.00/gal.) = 3,880 gal. of gas to travel 60,000 miles --->>> you're comparing an EV against ICE vehicles that get ~ 60,000 miles/3,880 gal. = ~ 15.5 MPG. I suppose that's one way to construct EV justification logic, and maybe the way I might look at it if I was driving two gas pigs that got crappy gas economy. But, I'm not sure that your situation qualifies as typical with respect to the common folks vehicle's gas mileage. What were you driving before the EV's ? Even a Rolls Royce will get you 14 MPG according to the EPA for 2016 models.

As for numbers of totally electric or non conventional vehicles in the U.S. fleet, EIA numbers for 2018 claim ~ 243 million conventional fuel autos and light trucks in the U.S. fleet.

Of that total, about 420,000 are 100, 200, or 300 mile all electric vehicles among the 10.05 million "Alternative Fuel Cars". The rest of that 10.05 million includes ethanol-flex fuel cars (4.85 million), and electric - gasoline hybrids (4.28 million), with the rest of the remaining ~ 530,000 alternate fuel vehicles being mutts of various types.

If we confine our definition of electric vehicles to be only those that run on vehicle stored electric power only, it looks like the EIA numbers would show ~ 0.42 million / 243 million = 0.17 % of the U.S. auto fleet to be electric powered.

As you say, maybe your section of whatever state you live in has a higher percentage. I try to be less parochial in my outlook and perspective.

**reastman** · 12-06-2018, 02:27 AM

Great outline, reminder to stick to a path and insights to consider while remaining logical vs emotional in making the decision - Thank you, thank you

Here is what I have done:

Had energy audit done
Consider what I want to change or not change based on that info
Make changes to reduce load
Determine current charges on electric bill
Changed electric plan based on what/when Im being charged
Educate myself on solar (read, read, read)
Ask those more experienced
Set up a call with a solar advisor from EnergySage
Speak to several installers

To answer the questions:

Size of systems being quoted:
3.58 - 4.62

What I thought I understood about determining cost per KW from the bids, I dont think Im very clear on. I thought you took the price of the bid and divided by the size of the system. That is confusing when looking at the bids coming in through energy sage & those locally.

Here are the numbers: All cash and before incentives

Cost: $15,444, System size: 5702, Energy sage & installer state $3.90 price/watt, 108% offset, Sys Size: 3.96kw

$11,440, 5414, $3.20, 103%, 3.58kw

$13895, 6506, ($2.13, but I dont think Ive got this right) so ???, 97%, 3.90kw

$14813, 7157, ($2.06 but ???, same as above), 107%, 4.29kw

$17812, 6849, ($2.60 but ???, again I dont think I know how to calculate), 90%, 4.62

Shade: None
Plenty of space, no trees,on both south facing & west facing roof

Electric company billing: .29 - they were charging higher rate 4-9; 7 days a week TOU. I just switched plan to higher rate 3-7pm Mon - Friday TOU and 15 days Smart Rate

Offsets being offered: 90-108% (really like your point that an oversized offset may not be as cost effective as a less offset).

Not sure Im understanding completely the PVWatts question you posed: But this is what I got for results when I ran that
PV System Specifications (Residential)
DC System Size 6849 kW
Annual 5.92

Is that what you were asking?

The consideration to get solar is to simply fend off the increased prices of electricity in future years.

Thank you again for such a clear & concise path for me to consider & take...

**solarix** · 12-06-2018, 06:58 AM

I bought a ChevEV (BoltEV - with a "B") 2 months ago and freaking love it. I run so much on-grid credit from my solar array that charging the car before 7pm is virtually free for me and the car was less than $30K after the tax credit. I don't do any long distance driving, but now, we just need the non-Tesla charging network to get built out to make EV's viable for just about everyone. I think that most people will be driving EVs within 10 years. Cost-effectiveness aside, electric drive is superior technology, EV's are fun to drive, and have none of the maintenance hassle of a combustion engine. (not to mention less environmental impact)

**Ampster** · 12-06-2018, 11:11 AM

Originally posted by J.P.M.

...............EIA numbers would show ~ 0.42 million / 243 million = 0.17 % of the U.S. auto fleet to be electric powered.

As you say, maybe your section of whatever state you live in has a higher percentage. I try to be less parochial in my outlook and perspective.

Yes, my view was strictly from my experience In Northern Cafifornia where the numbers are even higher than California in general. This quote from Curbed online magazine is only for 2017. All indications are 2018 will show continued growth in California.

"As of October 2017, the state has 337,482 zero-emission vehicles (ZEV). While that only makes up 4.5 percent of the state

**J.P.M.** · 12-06-2018, 12:45 PM

Originally posted by reastman

Not sure Im understanding completely the PVWatts question you posed: But this is what I got for results when I ran that
PV System Specifications (Residential)
DC System Size 6849 kW
Annual 5.92

Is that what you were asking?

If your defining post and thanks was in response to my first post to this thread, you're most welcome.

Additionally, welcome to the forum of few(er) illusions.

To your question: My question(s)/comments about PVWatts were meant to suggest that you can get your own estimates of what size PV system fits your needs and your goals as well as or more than likely better than peddlers can or will do because those peddlers main goal is to make money by putting more product on your property and NOT primarily helping you get the safest, best designed and most cost effective PV system consistent with the required duty as you define it. That, and a nudge from me in Dutch Uncle style that your job is to be as informed as possible to make sure those and your other goals are met through education - as you have noted in your response.

To the self education end:

1.) Read the PV Watts help/info screens a couple of times before you attempt any sizing. Kind of like reading/studying the driver's manual before taking the tests for a driver's license.
2.) Get the proposed array orientations used for the PVWatts model as close as possible to those where the array is to be placed. Array orientation affects output annual production and other things.
3.) Use a 10% systems loss parameter rather than the 14 % default the model starts with. Many knowledgeable users have found 14 % is too mostly/often too conservative, and 10 % usually gives a better (closer) fit to reality.

4.) Buy or (free) download a copy of "Solar Power Your Home for Dummies". It's a bit dated (2010 /2012), but since PV, as a technology, is pretty mature and was never rocket science to begin with, most of what's in the volume is still valid at least in terms of the basics. Read the book before doing any (more) work w/ the PVWatts model, particularly the parts about conservation and energy use reduction - the real most cost effective and so the first measures taken to meet your stated goal of reduced energy bills.

After all that, and with your additional knowledge, including that acquired from really digging into how you are now and can be charged in the future for power, as well as how things have and will continue to change in those respects, come back here for answers and fill in any knowledge gaps your newly acquired knowledge creates.

Iterate the above process and in so doing refine your goals, budget and system preliminary system design. Then, call the original and/or other vendors and tell them you want their best price and work for what you're pretty sure fits your needs, and give them a written description of what you expect from them in terms of equipment size, type and quality. Get their prices but DO NOT SHARE competing vendors' prices. You will only pay more in the end. "Price matching" is an old sales trick and the errand of fools who fall for it. Then, negotiate tough but fair and remember that a vendor can skimp on quality in ways you will never know, so squeezing them too hard can be counterproductive to your goal of getting the most long term bang for your buck - which is a lot different than getting the lowest first cost - another errand of fools.

**Sunking** · 12-06-2018, 04:13 PM

Originally posted by reastman

Location: Santa Maria, CA

Pay me in Tri-Tip and I will help you.

**littleharbor** · 12-06-2018, 04:53 PM

Originally posted by Sunking

Pay me in Tri-Tip and I will help you.

Hell, I'd do it for a couple jugs of Suzie Q's Tri-Tip seasoning.

**reastman** · 12-11-2018, 01:02 AM

Ok you both win. We make a killer tri-tip on an open oak wood fire, marinated in Suzy Q....lol

**reastman** · 12-11-2018, 01:35 AM

So I am down to two choices.

Hanwha 320, 5000/6000 solar edge inverter, 14 panels, $3.10 per watt

Hanwha 390, 5000 solar edge, 11 panels, $3.28 per watt after $1000 cash back from installer.

This week I learned how to calculate per watt.

Question for the week: what considerations should be taken regarding design?

2 design ootions.

South facing roof shows higher production vs a split design of south & west roof.

West roof production, at time of day that PG & E charges higher rates.

Your insights are appreciated.

**Mike90250** · 12-11-2018, 04:10 AM

Your payback is reducing your rate paid, not total production.
This is where your local micro climate has a huge effect. If you put your panels on west, and you have marine layer fog daily, you loose.
If you put them south, and you have clear afternoons, you loose.
If weather is clear, I'd put 1/4 E, 1/4 S, and 1/2 W to offset as much as practical, the peak rate period. Do the math, figure your climate, see what works

**J.P.M.** · 12-11-2018, 12:42 PM

Originally posted by reastman

So I am down to two choices.

Hanwha 320, 5000/6000 solar edge inverter, 14 panels, $3.10 per watt

Hanwha 390, 5000 solar edge, 11 panels, $3.28 per watt after $1000 cash back from installer.

This week I learned how to calculate per watt.

Question for the week: what considerations should be taken regarding design?

2 design ootions.

South facing roof shows higher production vs a split design of south & west roof.

West roof production, at time of day that PG & E charges higher rates.

Your insights are appreciated.

From your prior posts, you have no shade and will have net metering and probably be on T.O.U.

First design consideration is how much of your load you want to offset, but it looks like that's already been somewhat decided.
Because the array size has been set , the next decision is which panel configuration and orientation mix will produce the greatest bill offset.
My strong feeling backed up with more numbers than will fit on this forum, and as I've somewhat described recently in other threads is that for most of CA, for residential users on a T.O.U. NEM tariff, a south facing array orientation will produce a greater bill offset than a west facing array. Therefore, if I were you, and knowing what I know, I'd put all panels in the southern orientation and skip the west orientation.

You can do as I've done for SDG & E and my location and generate your own estimate of the difference.
-This works for true T.O.U. NEM tariffs only.
-It will not work for semi T.O.U. tariffs that have tiered rates laid over them.
-It's a bit of a PITA as it requires really digging into the tariff/rate plan you think is best for you.
-But, if you're still interested, and if you have a true T.O.U. tariff, and are a bit detail oriented, I'd suggest you consider doing the following if you want to confirm my opinions and findings for south vs. west or any number of orientations :

1.) Run PVWatts for your location for both or any other array orientations you may be interested in. I'd suggest running a 1 STC kW array size - it'll make output comparisons easier. Get the PVWatts hourly output option and download it to a spreadsheet. All 8,760 rows.
2.) This is the PITA part: Put each hourly per kWh energy charge from the POCO's rate sheets in the appropriate hourly column on the downloaded hourly PVWatts spreadsheet. DO NOT FORGET THE HOURLY ADJUSTMENT FOR DAYLIGHT SAVING TIME. The POCO uses local time. PVWatts hourly output does not adjust for DST.
This task is not easy, but it's not as daunting and gargantuan as it may at first appear. Here's why: Most of the weeks in a year are of 3 types - winter, summer and probably some spring off-peak adjustments for March/April. Do a 168 hr. week for each of the three. Keep the DST adjustment in mind and don't forget the 5 holidays of off peak times ( I add them as a change after all else is done and checked) . Then, copy each week as appropriate to the spreadsheet. A lot of copying but also a lot easier than I first thought. Took me ~ 1 hr. and ~ 1/2 hr. of checking/correcting, but I'm mostly a Luddite.
3.) Multiply the hourly output for each orientation by the POCO rate for that hour. That will give you the value of an array generated kWh specific to that hour whether that kWh is used to offset a kWh NOT drawn from the POCO or set back to the POCO and banked for future use.
4.) Sum the columns that have the hourly output*hourly rate product for each orientation. The result for each orientation will be how much "revenue" each STC kW of each array orientation can produce to be used against how much you're billed for. This method will consider an array's hourly output for an orientation while also accounting for a POCO's rate for that hourly output.
5.) Compare the "revenue" for each orientation.
6.) Choose the orientation that suits your needs and goals as you see fit.

One note: Besides only working with true T.O.U. NEMs, the method will not produce correct "revenue" generation for systems that produce excess generation. What it can do in those cases is point out just how cost ineffective excess generation can be, but that's another topic.

As an example of using the above method for south vs. west array performance for my location only (92026), using SDG & E current rates and schedule DR-SES (T.O.U. for users with PV systems):

South facing, 20 deg. tilt:
$449 annual "revenue"/STC kW
1,720 kWh/yr. per STC kW
$0.26097 average value of each kWh of array generation.

West facing, 20 deg. tilt:
$415 annual "revenue"/STC kW
1,530 kWh/yr. per STC kW
$0.27092 average value of each kWh of array generation.

So, while the west facing array will produce a slightly greater value per kWh generated ($0.27092 vs. $0.26097), that advantage is more than offset ( $449 - $415 = $34/yr. per STC kW, or $34/$415 = ~ 8.2 %) by the greater south facing array's output (1,720 kWh/yr. vs. 1,530 kWh/yr.).

For my location only, but I'm quite confident other locations and POCOs in CA will produce similar results.

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

offseteU

1st real post, equipment comparing

1st real post, equipment comparing

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