DIY solar/worth the cost?
 

Due to some unforeseen good fortune this past year we have found ourselves faced with 2 things: 1. larger than expected income for '16 and 2. Much larger than expected tax bill coming in April!! :eek:

I'm really wrestling with doing a DIY solar, as it is the only viable deduction at our new income level (which will be a 1 year thing, next year its back to normal).

Facts: We have 2 EVs in our household. We use about 25kWh per day for the vehicles alone. On our power plan this bumps us up into tier 3 (14.5c) every month.

We have had 2 large national and 1 local solar company bid the job. All have estimated that we "need" about 10kWh system. Bids range from 32k to 36k. Not going to happen. If we do this project we want to pay cash and that is just beyond our range at the moment.

By browsing the live data from actual installs in my area of similar size I have calculated that 10kWh systems nearby return about $135 per month on a one year average. Our power company does annual reset on net metering with no monetary credits, so it does no good to over-generate.

I've found a quality system (Mitsubishi MLE280W panels and Solaredge power optimizers and Inverter, mounts, wiring, support) for exactly $18170 delivered.

With Federal and State tax credits calculated ($8300) in it's about 8 years to break-even. :(

This still seems like an unacceptably long time. Especially if you look at other investments that you might miss (opportunity cost).

Would we be better off waiting and just paying the extra $8300 to the gubbermint??

Would a smaller system make sense?

The synergy of having electric vehicles with solar really appeals, but something is holding me back from pulling the trigger. Any insight from the wise eco minded renovators?? Comments?

:thumbup:

Well as I see it if you pay $8300 to the gov the break even is never you lose $8300. Or take the credit and in 8 years your even. I've been in my house 24 years, so wish I could have done solar way back when, now I'm disabled so lose out on the tax credits and can't physically do a self install, so I leased a system. Still saves me after the lease fee. So I'm happy

Roostre,

There is more to the equation than you have written - and when you see it you will be quite pleased.

Like you, I put in a similar sized system. Mine is 12.9 kW and I looked hard at the "return on investment".

First, go to Renvu.com (link below) and look at Enphase systems. I just installed a 10 kW system of Hanwa 265 W panels and Enphase M215 microinverters (with roof racking) for a delivered materials price at $1.02 per watt. This is an ideal system for a self install.

Secondly, the two estimates you got ($32K and $36 K for a 10 kW system) are in line with what I charge ($3/watt; materials and labor). Assume you do a 10 kW self install system with materials cost of $10K. Your true value in the home is double that ($20 k labor "fee") as you have improved your home value by $30 k ($10k+$20k). There is a lot of data out there showing that homes with PV sell for more than the installed cost of the system. You cannot deduct your labor or get the tax credit for it, but in reality, you have substantially improved your home value. But for now, let's assume your home is improved by some 200% more than your materials cost.

Thirdly, your self installed system ($10K materials cost) will get you an immediate 30% residential tax credit. On a $10K materials purchase, this will be $3K from the Feds. Looks like you have an additional state credit of 15% so that will be another $1.5k for a total of 4.5 K. Your actual basis is now $5.5 k looking forward (not $10K).

Now it gets interesting. You utility structure has you in a bind being in the expensive high tier ($0.14/kWhr).

The savings of $135/month you see from neighbors may or may not be correct. You can go to PVWATTS and find out how many yearly kWhrs you should expect. Beware that the assumptions in this program (defaults) are VERY conservative and are out of date. For example, PVWATTS assumes a system efficiency of 86% where the Enphase inverter efficiency is 97%. But with good inputs it will get you close. I have found that even with good inputs, my Enphase systems produce about 10-12% more monthly/yearly kWhrs than PVWATTS predicts.

Let's assume you save what you have seen - $135 a month ($1620/year). On the simplest of return calculations your basis is $5.5 k and you save $1.62 K per year. This is a 3.4 year return on investment (ROI). Using the rule of 72, this is a 21% ROI.

But it actually gets better . . . . In reality the $1620 you save per year go to other financial perspectives and this "saves" you some 2% per year (lost opportunity cost). The 2% figure is conservative, but it gets you there. Then assume the cost of electricity will increase significantly above inflation for many years. Choose your percentage (let's use 5%). Adding 2 and 5% together give you a 7% figure on savings per year. You can now do a reverse amortization to figure your ROI, but lets use the "rule of 72".

This gives you the time to double an investment given a percent return. 72/7 = about 10 years. So just the savings on your system give you a doubling of investment (basis) in 10 years.

The bottom line of all this is that the internal rate of return on a self installed solar system is on the order of 20-30%. And doing it yourself only adds to the savings.

Another way to look at it is to add the tax credit ROI (21%) with production situation (7%) for a total of 28%. Again the rule of 72 gives you a payback of ~ 2.6 years. But you are also saving on electricity, so the actual ROI is even better.

No - the return is NOT 8 years but certainly less than 3, maybe 2 or so.

The negatives . . . . Climbing on the roof is not easy, but on a self install, you are "making a lot of $", so it is well worth your time (~ $500 per hour). A self installed system of 10 kW (~ 40 265 W panels) is about 40 or so total one person hours ($20,000 divided by 40 hours = $500 per hour). Maybe it takes you 80 hours - heck that is still a lot of cash you are saving.

You may need some basic tools. Socket wrench, cordless drill, measuring tape, ladder, etc. Nothing out of the ordinary.

You may (or may not) need a electrical permit to do the final hookup. I am an engineer, not an electrician, but you can hire an electrician to help or to go over everything at the end.

My prices are current as I just ordered from Renvu this week (Hanwa 265 w panels at $0.51/watt and Enphase microinverters at $90 each). To get prices, you need to register, but that is easy.

renvu.com | Search By

Hope this gets the wheels turning . . . . . .


Steve

Oh, the virtues of sweat equity... With nearly all of these ecorenovations, the return on your own labor pays back in tangible dollars quicker than estimated (if you do it right the first time). Besides saving the prevailing wages charged by skilled tradesmen, another adventure is added to your life story and skill set. If and when something goes awry, be it the system, the economy, the power utility, or whatever, you will be in a better position to deal with the change. Having commissioned the rig, the cause and effect relationship will be known without having to call on "the guy". Later, if you want to expand, the process will be much easier than the first time through.

Plus, you can share pics with all of us. Everyone wins!

Good luck making your decision. Everyone I know (especially those with electric cars) that has commissioned a PV system like you are contemplating had no regrets after the fact, except that they didn't go bigger earlier.

Roostre,

Renvu is a superb place to get advice for first time DIYer such as yourself. I do strongly advise against central inverter units and power optimizers.

Several people on this site have installed Enphase microinverters and it is really simple. Maybe they will chime in.

Lastly, avoid the perspective to "just wait, the price will come down". The solar industry will have further declines in modules and inverters, but at $1/watt for materials, we are getting close to basic manufacturing costs. For example, racking costs are fixed and are about $25 per panel. The basic cost of aluminum rails, nuts/bolts/screws is right there. The further price declines (next couple years) will only be a tiny fraction of the declines we have seen in the last ten years.

Waiting just reduces your ROI and you need to do something now considering your 2016 impending tax situation.

I agree with Jeff that putting in a too small system is a waste of time. Do it right the first time. The best way to do this is to design your system size correctly. I gather you have an annual metering so that you can "store" or bank kWhrs in the summer for winter use. Is that correct?

If it is, then you are very lucky.

Might be helpful to show us your month by month kWhr use as well as the charges per kWhr throughout the year. That way, we can assist you on designing the "right" size in kW and panel number. You are exactly correct that too large a system is a waste.

An intermediate install plan would be to hire a handyman that is not afraid to work on the roof. Let's say, you pay him $25/hour and the job requires some 40 hours. You are out some additional $1000 for labor, but then you still get some 45% back of this $1000 (fed and your state credits). Beats paying a solar installer some $20,000 + to put in $10,000 worth of solar materials (panels, microinverters, racking, wiring).

The last thought I wish to leave you with is that Enphase has a 25 year non-prorated guarantee. This is through Siemens. I have had to only replace one Enphase microinverter (of many hundreds) and it was here in four days with pre-paid shipping of the bad unit back.

Let us know how to help. Even though it is just a "nuts and bolts" install, this is a major project, let's be realistic. But it is one that will have incredible financial and satisfaction perspectives.


Steve







Steve

@Stevehull
We want pictures and a solar post on its own about your project. Please share your story to help others.
It is a good story that others can reproduce.

I was going to post to this but Steve has done a great job.
Here is my story.
http://ecorenovator.org/forum/solar-...lar-array.html
I even installed mini splits so I could heat with solar power.
I personally think it is really worth it. No regrets at all.
Our Chevy Volt just hit 59,587 solar powered miles. We have had two years with covering everything with solar.

you said.
"Facts: We have 2 EVs in our household. We use about 25kWh per day for the vehicles alone. "
We charge our Volt from empty 2 - 3 times a day so we have 25+ kWh a day charging also.


I also installed enphase and there is a lot of info out there to do a by the book install.
I think this is the simplest install for a DIY person. The per panel monitoring is so good at a glance I can tell every panel/ microinverter is doing what it designed to do.


My return on investment is greater than the stock market and I am helping the environment at the same time. Win Win in my book.

Steve,

Thanks for the information, links, and enthusiasm!

Our power company will not pay for spinning the meter backwards, but in reading the "Net metering service" agreement they credit any generation forward to the next month. All unused credits accumulated expire with the regularly scheduled meter reading in March each year.

I have been following your thread for quite some time and it is an inspiration to make the leap!

Many of my skeptical friends say that the system maintenance costs will erase any benefit. Have you experienced any issues? How often do you need to clean them?

Was going to reply also, but like Pinball, realized that Steve has just about said all you need.
Go for it if physically able. You will learn a lot also.

You did not say what your age is or your physical capabilities. I'm over 70 an would DIY solar in a moment if I lived in a good solar area (In western WA, not enough sun esp. since I would not want to cut down my 170 ft trees!)

Since you are in Utah, back in the 1980s, when solar was more than 5X as expensive in inflation adjusted dollars as now (ain't tech advances GREAT!) we did a study of using solar power for a missile base in S. Utah/Nevada and saw areas where the LONGEST stretch without sun was 3 day during the previous 40 years! So, you may be in a great area if in the South of Utah.

Even back then, the solar would have been lower cost (including then state of art hydrogen/bromine fuel cell storage) than building a dedicated new power plant plus distribution lines.

How often do you need to clean them?

Posted before I say your question. The study from the early 80's I mentioned looked at the maintenance costs, specifically cleaning.

With the exception of cleaning after severe dust storms, never. The penalty was a 4 to 5% reduction in electrical output.

You can do your own trade on value of your cleaning time vs. say a 500 W loss of output on a 10kW array.

We are in northern Utah and up against some beautiful mountains; that is why I spent some time looking at the historical data from my neighbors. Sunrise takes a little longer coming up over a 10,000 foot wall of granite. (Due east of our place)

This weekend I am taking out 2 trees and trimming back a few more. Have a lift rented and hoping I can get them down safely. I'm 47, but my Son-in-Law is helping so it shouldn't be too bad. Great kid who is always eager to help me with projects. He is already on-board to help with the Solar.

One more PS:

What is great about this site are helpful pros like Steve: If you went to someplace like HVAC-talk.com for heat pump advice, all you would get from the 'pros' is a statement like: "you are too dumb to know how to DIY a heat pump (or solar), so better hire a pro".

My system went live 04/12/2013 9.2 Kw shortly after that I added more panels 12.5 kw.
I have done nothing at all except one time we had a freak snow storm and I pushed some snow off to get them producing faster. (This was not necessary)

I probably should clean them off but production is still strong. It just works.
http://ecorenovator.org/forum/attach...1&d=1476464778

Flynns Arcade 12.560kW | Yearly
I look at my online production at least once a day but I am on a computer/phone many hours a day.
I do keep an extra microinverter on hand just in case. But I have not needed it yet.

I told my neighbor I was installing solar they laughed at me and said good luck with that working out.:)

Just gets better and better, that bonding with a SIL doing constructive work is worth it all by itself !!!!

Grip 4-Head Suction Cup Dent Puller | Auto Body Tools| Northern Tool + Equipment
You can get it other places.

http://ecorenovator.org/forum/attach...1&d=1476466217


If you install solar get this tool.
You put the lock the cups on the glass on the panel. Then one person can carry the panel under your arm like a briefcase. I carried every one of a panels with this tool.
It works so well.

Knowing you are driving your EV using the sun’s power is such an amazing felling. I know you can’t take a felling to the bank it is still priceless.

Roostre,

Read pinball's entire posting - yes, all the pages. I really like the IronRidge set of rails that mount to the roof. There are three strengths. Depending on your snow load, you may need one of the two heavier ones; I have only used the XR-10. You can buy these from Renvu as well.

What type of roof do you have, what is the roof pitch and how much is exposed to the south? Don't worry about the early morning sun (coming over the far horizon granite) - it is not a huge contribution. Any roof pitch from 2/12 to 6/12 is fine. Steeper pitch's (> 6/12) need a lift basket as you can't walk on them. You don't need a perfect solar south orientation either. Anything within 25-30 degrees of solar south is fine.

You can get the roof pitch from an iPhone as degrees. You need roof pitch in degrees to input data into PVWATTS anyway. The iPhone also has a great compass that can be set to either magnetic or true north. I set mine to true north and use the iPhone for both roof pitch and for solar south orientation in degrees. Hint - to get roof pitch, you go to the compass and then move the slider at the bottom of the screen. Then put the iPhone on edge and it reads out degrees of pitch! Really, really handy. Is this on Android type cell phones?

Maintenance? Huh? What? There is none. Maybe some dust decreasing the output by a few %, but you can use a home type sprayer washer to hose the PV panels down if you get anal compulsive (I don't do it; it rains enough to keep them clean).

Lots of people say you can't do this stuff unless you are some engineer - but the people on this site can talk you through ANY of the minor issues. Mostly nuts and bolts . . . .

Great idea for the suction cup device that pinball suggested (above).

Plan on some 40 hours planning and layout, then 40 hours putting it up. Every hour of planning saves two when you are up in the air.

Why not send us some pictures of the proposed roof area?

Lastly, find someone with climbing harnesses that you can borrow for safety.


Steve

Power Generation Issues: NONE since system went live 8/1/2013. :thumbup:
Cleaning: More than a dozen of my panels have never been cleaned in 3+ years! I cleaned two at year 1, four more at year 2. I used a Mr Clean Magic Eraser mop and hand washing dish soap and cleaned just a few to determine if any appreciable energy was available from cleaning. For me, the answer was NO. When comparing them in my energy production graph, after year one and year two it was nearly impossible to tell the panels I washed from the panels I didn't. At year 3, I'm sure they could all benefit from a wash since I saw some minor mildew growth on the glass when I was on the roof installing an anemometer a few weeks ago (just before the tropical storm called Hurricane Matthew). Cleaning my panels on the second floor stone coated metal tile roof is not for the faint of heart. I did all the work installing the PV system myself, but I still respect the second floor fall potential working on the roof. If I don't need to wash them, I don't! I live in a nearly sub-tropical climate where I get heavy rain, frequently. Dust is never a problem. Oak pollen is a minor issue certain times a year, but a good rain washes that away without human intervention. :thumbup:

As others have mentioned, there are literally enough of us with Enphase systems to explain anything you need to know.


My System: Self-installed, self-designed, self-permitted documentation(other than the structural engineering to survive a 3-second gust of 170mph, and I picked out the specific parts for the engineer to choose from to perform his wind load analysis calculations)
Panels: 4.4kW (20 panels, 220W Evergreen [after bankruptcy] Black frames)
Inverters: Enphase M215 (with MC4 connectors, Qty: 20)
Mounts: Unirac Creotecc Tile Hooks (qty: 102)
Racking: Unirac Solarmount (bronze, three rails per panel to achieve wind load rating)
End Splices: Unirack Solarmount Splice (bronze, one between every end butted rail, Qty:6)
Trunk cable: Enphase landscape, (26 drops)
Enphase Trunk End Caps: 2
Wire Mounting clips: Stainless Tie-wraps 11" (found them on clearance, cheaper than any solar track wire clips I could buy)

Roof Junction Panel: Hubbell-Wiegmann HW-80604CHSC (fiberglass)
Panel Subpanel: Hubbel-Wiegmann HW-MP806FG (fiberglass)
Terminal Blocks: Automation Direct DN-T10-A (qty:8)
Terminal Block Brackets: Automation Direct DN-EB35 (qty:2)
PVC Cable Glands: qty:4 (sized appropriately for Trunk/TC-ER cable.)

Tray Cable: General Cable 279910 (UL TC-ER rating 12awg-4cond, runs between roof junction panel, down a weatherhead, and to the attic junction panel)

Attic Junction Panel: Carlon 8x8x4 PVC junction box (qty:1)
Terminal blocks: Automation Direct DN-T10-A (qty:8)
Terminal Block Brackets: Automation Direct DN-EB35 (qty:2)
Terminal Block Rail: Automation Direct DN-R35SAL1-2 (qty:1)

Attic to PV Combiner Wire: UF 10/3+G
Rack Ground Wire: Bare 6AWG (solid)

PV Combiner Panel: Square-D QO QO816L100RBCP (8 space 100A)
PV Combiner Breakers: Square-D QO 15A (two pole, qty 2)
Wire PV Combiner to Main Breaker Panel: 6AWG (bulk, in three distinct colors, Qty: 6 ft per color)

PV Main Breaker: Square-D Homeline 30A (two pole, qty 1)

Rack Grounding:
WEEB 6.7 Grounding Lug (one for every rail)
WEEB Bonding Jumper (one between every end butted rail)
WEEB DMC Grounding Clips (one under every other panel pair attached with one mount)

System Monitoring: Enphase Envoy
Monitoring Wifi Connection: TP-Link TL-WN721N

Three-Line Wiring Diagrams: I drew those in AutoCAD, submitted as 11x17 paper copies. (at the time I designed my system, I worked for a company that designed A/V systems and integrated A/V gear all over the world. I was always drawing wiring diagrams, so drawing a PV system wiring diagram wasn't much different.)

Permits: My local AHJ required structural and electrical permits and multiple inspections. They also allow homeowners to do their own work on their own house, so long as the work meets applicable codes. I studied up on the applicable codes, asked questions where I didn't quite understand how the AHJ preferred to have things: like labels. I studied the appropriate version of the NEC being used, and designed the entire system to be NEC 2011 compliant. As a result, I can explain how the whole system works, top to bottom, Sunshine to 220Vac in my meter sub-panel.

I wrapped all the stainless tie-wraps with black heat shrink tubing to avoid electrolysis (separate the stainless from the aluminum mounting rails) and to limit potential wire chafing. It also disguises the tie-wraps from standing out like a sore thumb on the black rails. I painted the lowest visible tile hooks so the silver hooks don't stand out against the black track, black panel frames, and arctic blue stone coated metal roof.

When I assembled my components to build my system, I acquired things piecemeal as budgeting allowed and pricing seemed right. (my employment was in a bit of a downturn at that time, so I had to be frugal, but when I had second income from my part-time job I could put toward the project, I did!) My parts came from combinations of Civic Solar, AltE Store, Solarpanelstore, Automation Direct, and others. I had no bad experiences with any of the vendors I used.

If you look closely at the list I made above, you'll see some panel components I borrowed from my work experience behind the scenes in world renowned theme parks. UL Listed, NEMA 4x rated, weatherproof fiberglass panel enclosures by Hubbell-Wiegmann . Even my AHJ inspectors hadn't experienced those before. I simply opened the panel, showed them the UL Listing, the NEMA ratings, and the weather seal. They responded: You know your equipment. The terminal blocks I used in two of the panels: Attic and Roof, are also borrowed from commercial applications. They're UL listed, 30A, 600V rated and any AHJ inspector who has inspected heavy commercial work has probably seen them before. They beat the pants off trying to wire nut a 12AWG stranded to a 10AWG solid wire, sitting on the roof. Sure, a wire nut is cheaper, but I tend to use the best device for the application, not always the cheapest. :rolleyes: I can trouble shoot my terminal blocks on the roof without disconnecting the wires to get a meter probe in them.

Occasionally people ask about my Evergreen panels and "why did you buy from a bankrupt manufacturer, aren't you worried about warranty down the road?". My response remains: I have no guarantee any PV panel company will still be in business should I have a claim down the road. At $0.78/W in 2011, I was willing to take a gamble with panels from what appeared to be a quality manufacturer who couldn't compete with cheaper competition. I consider myself self-insured with the money I kept in my pocket the day I ordered those panels.

where2

Great post. I like some additional info on the fiberglass enclosures and the terminal blocks. I have used the 6" x 6" x 4" plastic Carlon boxes (Home Depot) as I can drill in holes for waterproof connectors. The Weigman boxes on their web site look better - any particular part number?

Like you, I never wire nut stuff together and am always looking for better terminal blocks. Any specifics there?

edit - just reread your post where you identified each of the above! Arrrgh, me stupid!
THANK YOU for the specifics!





Thanks,

Steve

Where,

The only thing that I would change on the panels is the connector, the MC-4 which is now the standard.

Have you seen any age degradation with your panels (lower peak power or lower peak daily energy)?

Whew - those Weigman fiberglass boxes are pricey! Take a look at this Carlon box from Home Depot at ~ $12

6 in. x 4 in. Junction Box-E987RR - The Home Depot


Steve

Here is another advantage of Enphase . . . .

A customer had an Enphase 6 kW system (I installed) where the Envoy (power and energy recording box) was acting abnormally. This box gets house wired digital signals from each roof mounted Enphase microinverter, converts them and sends info via Wifi or USB cable to the standard home internet router box. Then the Enphase Enlighten internet site allows you to see system total power, daily energy, each microinverter parameter (voltage, current, power, temperature, etc, etc). Very nice for geeky people like me.

Anyway, instead of the nice smooth parabolic power output that you should get over the day, there was nothing and then large square wave jumps in power output. Then all would be OK. The daily power output was appropriate, but the output curve was screwy.

I checked all my electrical connectors in roof junction boxes, at the circuit breaker and nothing was wrong. 120 V on L1, 120 V on L2, all OK. This is stuff I know - what was going on?

Called Enphase . . . They are able to look at FAR more data that I can see on their site. They have the means to see data, and where there is a fault, to capture all kinds of information (voltage, current, frequency, phase angle, etc) down to the msec on each microinverter. Turns out there was a transient L1 L2 imbalance. Normally L1 should be ~ 120 V and L2 ~120 V for a total for ~ 240 V across L1 and L2.

For a brief moment (a hundred msec, sometimes much longer, but always transient), these potentials became ~ 80V on L1 and 160 V on L2. The microinverters will accept some imbalance (5 V or so), but not this big. Note that the total potential is still 240 V - so the inverters are still sending out power. But the inverter was not sending it out to the internet in real time.

Both the Enphase tech and I immediately recognized this as a bad neutral. If the neutral is flaky or floating, then the ground is uncertain and you get odd split voltages on L1 and L2. The worst of this is that it was INTERMITTENT and incredibly short lived!

Enphase sent me the data by e-mail and I called the electrical utility company to come out and check the homeowners voltages - especially the neutral. They arrived and there was no imbalance at that moment.

The head lineman insisted that it was the customer's fault and a "capacitor was bad" on some 240 V appliance. He and a helper spent the afternoon looking and found nothing. Meanwhile I am looking at the electrical box behind their meter. This box has a wire "security" tag so that only utility people have access to that panel. This is a place that I cannot check.

Nothing in house - no issue with any 240 V appliance - and still no imbalance seen.

At this point, we are talking about having a voltage recorder put on the system and THAT is paid for by customer ($100 per day!!). The lineman also kept blaming the PV system and me (as I was installer) as the cause.

After they found nothing, and as a compromise, I suggested they look in "their" panel, the one the meter is mounted on to check those connections. "No, it can't be there" was the response. I persisted and said it would only take a couple more minutes.

Reluctantly, the panel was opened and each of the three lugs, L1, L2 and neutral were tightened (with insulated tools and rubber gloves on lineman). L1 was tight, L2 was a bit loose (took 1/2 turn to tighten), but the neutral was completely loose (3 full turns to tighten).

The utility repair person and helper were incredibly embarrassed, but I thanked them in front of customer and told them they did a GREAT job (never, ever piss off a utility person).

Now we had to wait to see if the problem came back. No it didn't and hasn't for months now. But here is the kicker . . . .

Turns out the customer had been having "odd problems" at times with appliances. Some lights would suddenly brighten, others would dim and some kitchen appliances would not work - then two minutes later they would work. Eeee gads! This had been going on for years (long before my PV install) and they just got "used to it" as it would go away. The imbalance was on a lot of the 120 V lines and it was lucky that nothing burned out.

Scary . . .

I called Enphase back and thanked them. They said they "see it all the time".

Bottom line - make sure your neutrals on your big junction boxes coming in from the utility are tight to the lug . . . .


Steve

In my 1AM stupor, I mistakenly noted those panel/inverter connectors were Tyco when they are in fact MC4 (now that I compared the two). I edited my post above to correct that.

Day to day, year to year PV output has so many variables that I cannot see any degredation. I'm sure it's there, because I believe the textbook science that says the output degrades 1% per year, but the palm tree that shades my array part of the day also grows taller each year. You'll note when I post my monthly data on the 12.5kW thread, I provide previous years data for comparison.

My house came with one of those Carlon boxes buried in the front yard as a junction box, it takes on water. I used a similar carlon box in my attic out of the weather, but for the roof I wanted something more robust. I drilled the Wiegmann box where I needed cable gland entrances, that's not a problem. They're uniform thickness fiberglass side walls and a forstner or spade bit went right through them.

There is a torque specification for the main lugs, sub-panel lugs, and the terminal leads coming off the breakers in most UL panels. However, most everyone seems to overlook that, and torque "to feel" without a measuring device. When I pulled out my torque wrench with the appropriate end bits and asked my AHJ inspectors if they wanted to check the torque of any of the bolts or lugs during my final inspection, they chuckled, said "If you a) know they are supposed to be torqued, and b) are offering us a tool to check them, then we expect you have torqued every one of the connectors to spec. Most homeowners don't know there's a spec, and most contractors develop a 'feel' for what's right and don't actually use a tool. Kudos for reading the NEC and knowing there's a specification for that." I had purchased the micro-torque wrench to torque the panel mount nuts on the racking to properly ground the WEEBs, it only made sense to torque the wiring connections if I already had the tool. I have heard electricians say they occasionally see lugs loosen over time, especially in areas with drastic temperature variations. The intense heat developed by arcing from a loose lug or loose meter blade terminal connection has been one of the concerns as smart meters were rolled out to consumers in my power utility. When the arcing caused a fire, consumers automatically blamed the "new smart meter" for the fire. I'm sure a fire marshal would properly diagnose the origination point for the fire if an inspection were performed.

What do you know about electrical work.
Because going from not being able to add a circuit to your home or replacing a switch or receptacle to building a diy solar system sounds like a recipe for disaster.

Roostre,

I believe you need to have the system installed and OPERATING by Dec 31 of this year to get the 2016 tax credit.

There is always GTA (good until audited), but I like to get things done "cleanly" for the IRS. No sense waving any red flags in front of bulls . . . . .

You have a lot to do - but we can help you. First off, we need your month by month kWhr consumption for past year and the associated costs for kWhrs in the varying seasons and for differing consumption levels. This allows us to figure out how many kW system. Then we figure number of panels. Then we look at roof to see how panels can go up and where. That determines amount of racking and wiring.

Not trying to be scary, but old man winter is puffing up . . . . .


Steve

An 8 year payback is a 12+% return on investment, which is pretty good in my experience. That's ~1.5x the real return of the S&P 500 over the past century.

:thumbup:

It wouldn't be 1.5x the return.
I considered this when I bought my solar system and mine doesn't beat the stock market.
If I consider a conservative average annual return for the total US stock market to be about 7%, that means the value would double every 10 years.
If I figure a lower cost solar system is $10,000(mine was slightly more) after the tax credit, ignore the delay in getting the tax credit money back, and consider the idea that the money put into the solar system is sunk until it comes back out, this is what my math looked like based on my own expected payback.

Solar installed(figuring 8 year payback, but mine is actually over 10) -$10,000
$-8750 Year 1
$-7500
$-6250
$-5000
$-3750
$-2500
$-1250
$0 Year 8
$1250
$2500 Year 10
$8750 Year 15
$10000 Year 16 (Took 16 years to double)
$15000 Year 20
$27500 Year 30

Of course, this isn't accounting for changes in electricity cost or net metering factors specific to your region or electric provider.

Stock market starting with $10,000 with 7% annual return
$10,700 Year 1
$14,025 5
$19,671 10
$27590 15
$38696 20
$76122 30

Compounding returns is powerful. You could take the returns you get from the solar system and invest those in the stock market, but even if you do that, you still need to consider that the price paid for the system is not going to be in the stock market and you've lost the opportunity cost for that initial potential principal. The idea that the original poster is about to otherwise lose the cash and is willing to DIY the install, I'd say that it's still a good move to do.

For what it's worth, the financial component of solar was a factor but I still wanted the solar and I figured it was better than spending the money on a couch, a car, or some other depreciating asset. It is fun for me to look my eGauge power graphs and see the power the system is generating and what the house is using.

I work in the power business. (Generation/transmission/distribution) 17 years mostly instrumentation and controls. Have friend that is a master electrician who is willing to help as I take good care of him when he does. I'm probably more comfortable with the project than most would be. It's actually the mechanical part (roof racking, shingle modification, snow load, wind load) stuff that I have blind spot in.

No pressure!! Right?? :D

We only recently moved into this house, so my data is limited.

July-1581 kWh August-1455 kWh September-1260 kWh

Yesterday was actually step 1 in this process. We rented a lift and took down 3 large trees. One of these completely shaded our southern side of the house, but it needed to go. I will add pictures of the roof in a separate post.

Roof2
 

Roof3
 

It may be obvious from the pictures; the entire front of our roof faces south. You can also see our shop in the backyard has a nice south facing area that might be used for panels, but I'm not sure how far apart they can be.

You can also see the service going into the left corner of the garage; it hooks into a 200 amp panel there.

That looks like it will work.
What direction is the roof facing?

Roostre,

First, you can get years of back monthly data (for years) from the electric utility. You just have to ask for it. You need monthly kWhr, monthly $ and the various rate plans. I like to get five years of data and get an average looking for odd months that are not consistent with other years.

Let's assume your yearly historic total kWhr consumption is 20,000 kWhr (1,666 kWhrs/month). This is not unusual.

Since you have yearly net metering, you "bank" excess kWhrs in the summer for winter use. Sweet - not many people have that. So we plan for a system that will deliver, for this example, 20,000 kWhrs.

I can help you with PVWATTS. This will tell you the amount of sunshine hours per month over the year. What is you local zip code?

From this, we get the number of panels. Let's assume a 40 panel, 265 W system. The panel dimensions are ~ 40 inches by 66 inches. Can you do four rows of ten on your roof? You will need to go up there and measure the roof carefully.

The least expensive way to mount panels is in the portrait configuration with mounting rails going perpendicular to that.

It looks like you have a 3-tab shingle roof (is that correct)? I really like the IronRidge "Flashfoot" attachment (on the Renvu site in the IronRidge section).

You can go to the Renvu site and they have very nice design software that will guide you to the type of rail strength, interval between roof attachments, etc, all dependent on your location (snow load, wind, etc).

But first steps first - get utility data, send us (me) zip code), measure roof and try out Renvu software on a simple trial system.

I am going to assume you have natural gas heat and conventional compressor type AC?

Assume you have put in LED bubs everywhere? That is actually the first step!

Get 'er done . . . . .


Steve







Assume that you have a need for

The whole house faces south.

I called and they will not give me previous owners usage information; it may be worth calling again to see if the policy varies dependent on the person you talk to like so many things in life.

xxxx is the zip.

LEDs was the first thing done. Gift cards from real estate agent were put to good use immediately. :thumbup:

Natural gas heater and conventional A/C system is correct.

I spent a few hours on Renvu, but I was mostly exploring their kit pricing not *really* understanding what I need per snow/wind, etc. I even tried to call my local building department with no luck.

Storm rolling in right now, but I will try and make some angle and dimensional measurements this afternoon. Thanks for all your enlightening help and support!!

The problem with your example is that you're starting off with -$10000 in the PV panel comparison. In either situation, you would start out with a +$10000 investment. In one, you put that money into the PV panels, and the another, you put it into the market.

You could deduct that amount you spent on panels at some EOL (although they should still have some residual value/generating capacity), but starting at -$10k is assuming you're spending $10k on the panels and another $10k on something else like installation. With that said, you should still invest your annual savings from the panels in the S&P, or some other broad index.

In your 25 year example, with PV panels at a real 9+% and the S&P 500 at a real 6+%, you should have a $10k initial investment in both scenarios. Granted, the $10k PV panel investment will depreciate, while the all S&P investment will do whatever the market does, but there's no -$10k starting point in the PV panel example unless those panels run you $20k.

At 25 years, in the PV panel scenario, you'll have the value ($2000?) of your depreciated PV system, plus your 9% earnings/savings, plus the amount that your 9% in annual earnings (savings from PV system) made in the S&P, less repair costs ($2000 for inverter replacement is the only thing I can think of), and less taxes on your S&P earnings. That should be about $22500(9% annual returns from the PV panels, so $75/month) +$28300(6% earnings on reinvested PV panel savings) - $10000 (initial investment) + $2000 (marginal value of PV panels) - $2000 (inverter replacement) - $28300*your_tax_rate($4200 at 15%), so about $36500-$40800.

The straight S&P 500 example will be the value of your initial investment ($10k) plus after tax earnings on the compounded 6% rate of return. That's $32,900(6% of the initial $10000, or $50/month) - $32,900*your_tax_rate + $10,000(initial investment). That would probably be ~$38,000 to $42,900 assuming your capital gains rate is 0-15%.

You're going to see a much larger difference in the next 25 years though (~$80k more from the PV panel scenario, less taxes), since the first 25 years of higher earnings in the PV panel scenario are offset by the depreciation of the panels.

Like you said, energy rates could drop a lot, but I wouldn't bet on it b/c the costs of the utility, transmission, and distribution are in my experience much greater than the costs of generation, and if people continue to install PV panels and/or disconnect from the grid, it's likely going to be more expensive for whoever isn't self-generating and/or off the grid.

On the flip side, it's possible that you could enter the market at a low point and decide to cash out at a high point, which would put the all S&P investment solidly ahead of PV panels at 25 years. At the same time, you could also enter the market at a high point, and be far behind the PV panels at 25 years.

My sense is the returns will be similar in the near term (first 25 years), and diverge in the long term (50+ years), with the PV scenario having a lot of depreciation (I'm guessing it's 40% once installed, even if it's brand new), but ultimately providing greater returns with less volatility in the long run b/c the PV panels are, at least at the moment, going to return 3% more in untaxed earnings/savings than the market.

Edited b/c I forgot about capital gains on S&P earnings in the PV scenario.

Roostre,

I assumed you have a roof pitch of 14 degrees (3/12 pitch). At least it looks like that from the photos.

Here is the solar radiation data for your specific area using the SLC airport (PVWATTS) using units of kWhr/M**2/day.

This unit is also called a "solar hour" as it represent the average amount of 100% sunshine hours you would get on an average monthly day hitting a panel at 14 degrees facing 180 degrees south.

For January, this means, on the average January day, you have about 2.55 hours of 100% sunshine "hitting" a PV panel at 18 degree pitch facing due south. This PVWATTS summary includes rain/clouds, etc so is a conservative number to start with. For the month, you multiply by the number of days in that month to get the total monthly solar "sunshine hours".

Note the July data where you get almost 8 total hours per day. In summer, you "store away" kWhrs for winter use and then it all gets wiped out in March where you pay some - or loose those banked kWhrs. The key is not to overproduce in the summer so you don't loose too much every March.

For estimates a 10kW system (40 panels producing 250 watts max) would give you about 17,000 kWhrs a year. If history plus your EV use shows a yearly use of 20,000 kWhrs, you would reduce your kWhr consumption by some 85%.

Your EV cars consume 25 kWhrs per day and that accounts for some 9000 kWhrs yearly (25 x 365). This may be a bit high as I counted every day, but on a M-F basis this is still some 6500 kWhrs. For an average call your EV consumption 7500 kWhrs per year. This needs to be added to the historical utility data (as I did above).

But 250 Watt panels in reality only put out 90% of that in real world conditions. That is why I couple 265 W panels with the M215 (that actually puts out 225-230 watts maximum. 90% of 265 = 239 W which is a perfect match for the Enphase M215.


Jan 2.55
Feb 3.65
Mar 4.65
Apr 5.64
May 7.03
Jun 7.34
Jul 7.60
Aug 7.14
Sep 5.95
Oct 4.63
Nov 3.05
Dec 2.10

average of 5.11

Now, we just need an estimate of those monthly kWhrs. If you could even get the YEARLY total, that would be a huge help. We don't want to put up more solar panels than necessary.


Steve
ps I have always gotten this data by asking for a supervisor if need be.

Ok, called the power company and got a much nicer operator. Although they cannot divulge previous persons info she was able to give me the following:

May2015-May2016 total KWhrs 14,761
Average bill: $153
High bill: $273
Low bill: $88

Keep in mind that we have 2 EVs added to this. It's funny that our highest bill this summer was still lower than the POs... the LEDs must be working. ;)


Measured the roof using a downloaded pitch gauge app. It read 3.9 on both the house and back shop. I'm going to guess it was built as 4/12 and the phone or app is a little off.


http://i.imgur.com/sv5zAAq.png



http://i.imgur.com/2pJGbGs.jpg