DIY Grid Tie 5.1kW for $0.77/kW

[5654684]

I want to share my solar experience with everyone on this forum. Half of the cost of a PV system is in the installation cost, so I decided to do that myself and post it here so it might help you.

First, a picture:


And the details:
SMA Sunny Boy 5000-TL-US
20 REC 255 pV panels

Snapnrack roof mounts (composite shingle) with flashed L feet

I bought the system as a kit, it came with all the Snapnrack mounting and grounding hardware, 2x 50' PV cable with MC4 connectors, a couple of Midnite Solar surge protectors.

Total kit cost was $8500, with another $300 for shipping. I had it shipped to my business address and unloaded the semi with our forklift and hauled it home in my pickup to save another $300 for drop gate service to the house.

I had done my homework on my roof (35 latitude, 150 azimuth, 45 degree pitch) and had my system sized for it.

I then went out and started shopping for local installers. The first installer quoted me $10,500 and I quit right there. That's more than another whole system. Also, keep in mind that your solar installer needs to be a licensed electrical contractor and that your quote for any electrical work needs to be between you and the actual contractor, not a third party solar installer.

Well, the parts arrived Nov 21 and to get the tax credit in NC, the system has to be functioning that year. So, here is my guide for a handy homeowner to install a grid tied solar system in just over a month in Buncombe County, North Carolina:

Get your building permit. I am outside the city limits, so no structural analysis had to be done on my roof. It is a two year old stick built house with 24" spacing between the rafters, just FYI. Apply as the General Contractor and pull a building and electrical permit. Each one of these is $75, so I spent $150 here. I had a licensed electrical contractor that was running the connections from the array junction box to the service entrance, so I listed him as the electrical subcontractor. In Buncombe County, NC, you can act as your own General Contractor on your own house for projects under $30,000. Also, as the homeowner, doing the work on your own house, not for sale or rent, you can do ALL your own electrical work. This is listed in NCGS 87-43.1(5a). This is how I was able to legally install the solar array on my roof.

Apply for interconnection with your local utility. I am on Haywood EMC, which is a co-op. I just applied on their website and got the go-ahead. Their max for residential is a 25kW system and they do net metering. When you finish your project and it passes inspection, they come out and install your two way meter.

Now, the parts and the paperwork are done. Next comes the fun part: installing the array. If you are moderately handy and you have a roof pitch of 7:12 or less, then you shouldn't have any trouble. I had a pitch of 12:12 (45 degree) and this brought more work. First step was to climb up to the top of the roof and take off one of the ridge vents and install the roof anchor for the safety harness/fall arrest system. This is the most dangerous part, but also one that gives you the most safety for the rest of the project. After this, clip in to your anchor wearing your harness and install your roof brackets so you can put in the top row of rails and panels. Here is a picture of this:


Here is another pic from the ground showing other roof brackets:


This allows you to work on a steep slope safely. Of course, when you finish one row, you remove and reattach the roof brackets for the next row. Once you figure out how to mount one L foot, the rest are all the same. Same goes with attaching the rails to the mounting feet and panels to rails. Before you know it, your 20 panels are up and ready to connect. Be sure to do a string connection diagram so you know where each panel is going to be hooked up to and always leave one connection unhooked (the easiest one preferably) until last.

This whole process took me about 5 whole days, and had the electrical contractor out there two of them. We even worked Christmas Friday to get it in by the end of the year. One detail I ignored until it was almost too late was the labeling of the solar system


It was too late to ship labels, so I had a local graphics company print me some so I would be sure to pass inspection. Inspection came on 12/30/14 and we passed at 10AM, and the Co-op hooked up our meter around 3PM.

So, cost of system: $8800
Permits: $150
Safety Harness, stainless lag screws, roof anchor, roof cement, roof brackets and lumber, other parts: $400
Electrical Contractor: $1900

Total cost: $11,250.00, which would be $2.20 per kW without incentives, but:
less 30% Federal and 35% State Credits: $7312.50
Total out of pocket cost: $3937.50, so more like $0.77 per kW

I welcome all feedback and comments.

Here is what makes it all worth it:

I had a few surprises:

I thought I could mount all 10 top panels and then 10 more on the right side of the roof. I ended up only mounting 6 on the right and 4 on the left. If you notice in one of the pictures, the edge of the panel is really close the the valley of the roof. I made it work. This mistake actually bugs me because I thought I had planned out everything. The steepness of the roof prevented me from getting all actual measurements, so I took a couple and then extrapolated the rest using Google SketchUp. This is a great planning tool, but remember that a computer is only as good as its inputs...

Other thoughts:

PVwatts puts out 6855 kWh/year on my system

The inverter has the wiring for the SPS, I just haven't connected it yet. I was in a time crunch to get this install on my 2014 taxes, so I left out that part of it. The shading you see was at 3:53 PM on Jan 10, and that was just the way it is. As the days get longer, that shading should diminish or at least be still about 30 minutes before the sun hits the tree line 150' away. I did wire the two strings to be on the left (West) and right (East) sides of the roof, so each string (and corresponding MPPT, the inverter has two) would be as similar as possible within the string, and one would maximize the morning sun and one would maximize the evening sun. The right (East) string includes the top right 4 panels and the panels directly below them (4 then 2). In a perfect world, I could have used microinverters, but that late in the day in the winter, it is not going to significantly decrease my power generation. I guess no one says "acceptable shading" in the solar world, but this is my thinking on it. I also want to leave myself the option of adding a battery bank in the future that would be grid interactive.

Also, I haven't stated this yet, but I am just an amateur with this whole solar thing. I think I have researched everything right and done everything right, but I very well may be very wrong. This is why I put my system out there so I can get the feedback.

With the drop in solar pricing now, I do think that you need to grab the bull by the horns, though. Solar is only about 3 years from being mainstream in my view, at least in my hometown.

Anyways, here are a few more of the photos of the finished install:

This is the service entrance on the side of the house with the two way meter.


This is the open service entrance, which has has small panel that we installed the 30 AMP breaker in that feeds the solar to the house from the inverter. This made it easier, ran less wire, and didn't take up more room in the main load panel.The local utility (Haywood EMC) requires the separate AC disconnect even though there is a 200 AMP breaker that they could cut off. I do like the fact that we can isolate the inverter without cutting all power to the house.

This is the junction box and dc conduit up the side of the house.

A closer shot of the junction box, at least from the ground.

 

[Where2]

Nice to see others join the DIY PV system owner's club. Nice write up.

 

[jebatty]

No matter which way a person slices or dices, solar pays. Congratulations.

 

[valuman]

That's a great write up of a very ambitious project. Congratulations on what looks like a job done well and special congratulations on going solar! Love it!

 

[peakbagger]

Given the shadow in the photos how did you split up the arrays for the input to the Sunny Boy (I assume its has two MPTT inputs)?

Did you give any consideration to installing a surge protector up on the roof at the junction box? I have only 1 mppt so I installed on Midnight solar SPD on the home run cables at the junction box.

In general looks like you lucked out in not having to meet the new NFPA standards for roof clearance and the new electrical code for the remote disconnect within 5 feet of the panels

Pretty generous incentives in NC.

 

[sloeffle]

What do you expect your ROI to be for this project ?

Very nice write up and pics.

 

[begreen]

Very nice write up. Thanks for taking the time to post it. What is the net metering payback per KW for your utility?

 

[5654684]

peakbagger - The array faces 30 degrees east of South, so the panels run roughly East/West. The top right (Easternmost) 4 panels, the 4 beneath them, and the 2 beneath them are on one string. The left (Westernmost) 6, the 3 beneath, and 1 beneath that are on the other string. This way, one string is compromised briefly in the morning and then another again in the late afternoon. The same effect could have been reached by wiring the top 10 panels in one string and the rest in another, but I would have had a longer run of cable to connect the bottom panels. The picture that shows the shading was taken at 3:53 PM on Jan 10. This is where a microinverter system would be preferable, but since the sun angles that late in the day in winter don't make much power, it was a tradeoff I was willing to take. Good eye there.

As far as the surge suppressors go, the kit came with one for the AC side and one for the DC side. I wired in the AC side one in the house entrance box that is mounted on the bottom. Since I have two strings, I would actually need two suppressors that would be mounted in the junction box. I only had one, and was in a time crunch, so I didn't mount that one. I do plan to buy another one and mount both of them at some point in time. Correct me if I am wrong, but these are mainly for lightning strikes. It seems that more surges could come from the utility lines than from the panels themselves, since the panels would have to receive a direct strike and the incoming lines could get a strike that follows the lines. Anyways, it is good practice to install both sides and I plan to do so in the near future. To do so would require disconnecting one section of each of the strings at a MP4 connector. This would have to be done at dark so there is no production on the panels. Good eye again.

The new NFPA guidelines just about gave me a fit when I read about them. Once again, it is my understanding that they have been adopted in California and it is up to each state as to whether and when they choose to adopt them. At the time of my installation, North Carolina had not adopted them. This is where you need to call your local building inspector. I called the county permits and inspections office and asked him specifically about this issue. His words were, "We can't tell you that you can't". They know the code is changing, but under current law, I can run my panels to the edge of the roof and not have a DC disconnect near the panels. This might change, but currently this system is grandfathered in. This might be fodder for another thread, but I don't see the advantage of this code when you have a mirror image north facing roof with no panels on it to make a ventilation cut and all my DC wiring is in conduit outside the house and is readily visible (with the exception of wiring through the concrete wall to the inverter) . I digress.

The incentives are great in NC, but they do have a catch. You can only claim a credit of 50% of your actual tax liability each year. You can roll that remaining credit over to the next year (or the next 5). My renewable credit this year was $3937.50, which was 35% of my installation cost. To claim all of it this year, I would have had to owed the State of NC $7875.00. I didn't owe NC that much this year, but suffice it to say that I can claim the remainder of the credit in the future. One of my goals in sizing this system was to have it paid for in one years time through Federal credits, State credits, and tax refunds. I borrowed money upfront to buy the system, but in a month, it will be paid off.

sloeffle and begreen - ROI and net metering payback are variable and here are my most recent numbers on it:

My co-op pays $0.059 per kWh sold back, which they say is the wholesale rate for electrical power. Currently my electric rate is somewhere between $.13 and $.14 per kWh. This is where it gets fuzzy with time of day usage. If I ran all loads during peak producing hours, I would get more payback. Here is the first bill I received:

This bill also reflects that we drained and cut off power to the hot tub, which I estimate was around Dec 30. This energy hog probably accounted for $70 in electric each month. This bill also does not reflect the whole time the solar system was connected, which was 12/31/14.

Next month's bill will tell more, but these are the numbers I am going by:

For January 2015 I made 540 kWh, and at the sell back all rate that is $31.86, so a simple ROI is 10.29 years
If I used all that power in the house at $.13 per kWh, then the ROI is 4.6 years.
Solar production will increase with more sun hours, so this is just a January baseline. We also didn't just do it for the monetary benefit, it feels good to know you are offsetting a little bit of coal.

NC also has a program called NCGreenPower that will pay you for generating power, but they don't do net metering, so you have to do a sell all system, and the homeowner systems are capped at 5kW.

I do not know what the renewable generation charge is on my bill. I emailed the co-op for an answer.

 

[peakbagger]

I am in no way picking on your install with respect to code. Many folks read these posts and use them to make decisions on future projects and the new code provisions can impact the cost and amount of PV that can be installed.

The standard response to surge protection devices (SPD) is that nothing will survive a direct hit but proper suppression may protect from an indirect hit. My racking and panels have a ground that goes direct down the side of the house to an auxiliary ground rod that is tied into the primary ground field. If the panels get hit, the goal is to direct the strike down the ground wire and keep if from heading into the house.

A general note on SPDs. My utility had an equipment issue and managed to surge my incoming power, I had a Delta on the panel and a whole house surge suppressor and sill Iost an inverter. I switched to the Midnight SPDs as the cut in point of the SPDs are much lower than the Deltas.

 

[valuman]

[

sloeffle and begreen - ROI and net metering payback are variable and here are my most recent numbers on it:

My co-op pays $0.059 per kWh sold back, which they say is the wholesale rate for electrical power. Currently my electric rate is somewhere between $.13 and $.14 per kWh. This is where it gets fuzzy with time of day usage. If I ran all loads during peak producing hours, I would get more payback. Here is the first bill I received:View attachment 154752

Next month's bill will tell more, but these are the numbers I am going by:

For January 2015 I made 540 kWh, and at the sell back all rate that is $31.86, so a simple ROI is 10.29 years
If I used all that power in the house at $.13 per kWh, then the ROI is 4.6 years.
Solar production will increase with more sun hours, so this is just a January baseline. We also didn't just do it for the monetary benefit, it feels good to know you are offsetting a little bit of coal.

I took a quick look at dsireusa.org because I thought NC had a net metering law in place and they do, but apparently it doesn't apply to the may co-op utilities in the state. Kudos to you for the installation as well as the desire to generate your own electricity using the power of the sun, regardless of the wholesale credit program.

 

[DBoon]

Kudos to you for a great install. Netmetering and modern technology make this far easier than it used to be in the days of battery-storage off-grid systems and many, many components, but your post highlights the skills (and they are considerable) to manage and install such a project.

 

[5654684]

peakbagger - I appreciate your comments and I don't see it as picking on. I hope this thread does help someone in planning their own DIY installation, and code compliance is definitely key in the planning process. You need to know your state and in some cases, local codes. I jumped the gun and bought the system before I knew exactly what the codes were. It all worked out in the end, but I would encourage anyone planning their system to not only call the building inspector's office, but their local utility as well.

Good point on the ground for the panels and racking going directly to an auxiliary ground rod. What are your thoughts on running a new ground wire from the racking to an auxiliary ground rod for my system?

valuman - I thought the same until I was ready to interconnect my system. I thought I would have true net metering instead of having to just sell the excess at wholesale generation prices. This really affects ROI. That being said, with doing my own install and the state and federal credits, when I plug into pvwatts, the cost of what I am producing is $.06 per kWh. I don't know what time frame pvwatts does this over. This is just above the $.059 that I get selling excess back. That being said, if I sold all back, the ROI would still be around 10 years. Solar is one of those things that there are intangible values in doing. It is not a strictly financial move, but one that gives you the knowledge that you are actively taking steps to lessen your coal footprint.

DBoon - thanks for the Kudos as well. There are quite a bit of hoops to jump through and skills to possess or learn when doing a solar install. I definitely had a steep learning curve in the whole project. The good thing about the internet and forums like this is that the information is out there. You just need to filter it for your particular situation. This is why my install only applies to Buncombe County, NC outside the Asheville city limits in 2014. Then you just need to roll your sleeves up and do it. I used to think solar was unobtainable for anyone but the well off West coasters. Prices have dropped and with the incentives out there, this is the perfect time to jump in.

In other news, I talked to Haywood EMC today for some clarification on the billing.

There is a $25.00 base charge each month just to have a connection. Use 0 kWh and your bill is $25.00
There is a $5.25 charge for renewable energy generation each month
kWh charge is $0.11754
and there is an energy efficiency rider of $0.00068 per kWh bought and sold
I bought 1099 kWh last month.

From 12-31-14 to now I have made 1112 kWh. Averages out to 550 kWh each month. Last month I sold back 324 kWh for $17.79 so I used around 225 of my own generation (for a savings of $26.45 from not buying that power from the utility). Take off the $5.25 fee for generation and I had an benefit of $38.99 this month on my bill. Extrapolate that out and the payback is 8.4 years. The payback will shorten with more generation in the summer months, and I will be using more of the electricity I generated to power the AC system (which mostly runs in the daylight hours anyways). Maybe the sweet spot on ROI will be between 6 and 7 years.

 

[jebatty]

I am an inveterate do-it-yourself kind of person, but I did not undertake my PV install, the main reasons being I thought the learning curve plus freeing up the time to do it (project was installed in October) before freezing and winter snows were too much for a probable one time effort. Now I'm going to be adding 5.2kw, and still having it done by a contractor. I have plenty of other things I really like to do, even though I wouldn't mind doing this one the second time around.

As to ROI, I never bothered with that in making the decision to install PV. Only after the system was in did I do the financial analysis. The fact is, ROI always has been secondary or lower on the list when my impact on the environment is the focus. The woods and meadows, lakes and wetlands, wildlife, smells and sights, peace and quiet, experiencing the cycles of life in real time, and more -- all are far more important to protect and preserve, because they are what makes my life possible, than is ROI.

In fact for the great majority of people, asking about ROI is laughable, because they have no investments, they have no savings, they have no retirement funds, and if they have anything, it is debt to fund consumption. Asking about ROI is a bait and switch argument for them, a distraction from what is important.

 

[peakbagger]

Good point on the ground for the panels and racking going directly to an auxiliary ground rod. What are your thoughts on running a new ground wire from the racking to an auxiliary ground rod for my system?

I don't claim to be a grounding expert but my understanding is that the ground grid needs to be interconnected. Auxiliary ground rods are a good addition but the auxiliary has to be tied into the primary ground point. As an example I have three PV systems, one is pole mount 200 feet from the house. It has a SPD on a local disconnect, the SPD and equipment ground is tied into an auxiliary ground rod and then I have a #4 copper conductor that runs in the trench with the DC conduit to a lighting pole. The light pole has an auxiliary ground rod and then a #4 runs in a trench along with the conduit to an artesian well casing and then continues to my main grounding rods for the house. The second wall mounted PV system has a ground running down to a auxiliary ground rod that is also tied to a #4 copper that runs along the side of the house underground to the main ground rods. The roof mount has a ground that runs along a soffit and down directly to the primary ground rods. The theory with a lightning discharge is that you want all the grounds at equal potential as if there are two separate ground points, one or the other may be more conductive and the surge will run through the house wiring to try to get to the ground point that is most conductive.

I agree its painful to buy and bury all that darn copper but if it keeps my house from damage, I bite the bullet.

 

[billjustbill]

I do not know what the renewable generation charge is on my bill. I emailed the co-op for an answer.

Thanks for your work and taking the time to show us! A 12/12 pitch must have made things harder.

First, I believe the "renewable energy charge" is the monthly charge they stick you with because you are causing them "book work"....

I was wondering what kind of liability clause they had? Do you have to provide a liability coverage through your homeowners policy to back feed to their grid?

Thanks,
Bill

 

[5654684]

The Co-op requires $100,000.00 of coverage under a homeowner policy. The complete details for my co-op are here:
(broken link removed to http://www.haywoodemc.com/content/rgr-rate)
In reading this, I also realized that I am selling back at $.0549 instead of $.059 per kWh, which is going to change all my figures on ROI. If someone is going to have to justify a system based on ROI, be sure what power sellback rate you are going to receive. For myself and others, just having the system is justification enough and everything it produces is icing on top of the cake.

 

[Where2]

Glad my utility doesn't bring in the insurance clauses until you pass 10kW system output.

 

[5654684]

I am an inveterate do-it-yourself kind of person, but I did not undertake my PV install, the main reasons being I thought the learning curve plus freeing up the time to do it (project was installed in October) before freezing and winter snows were too much for a probable one time effort. Now I'm going to be adding 5.2kw, and still having it done by a contractor. I have plenty of other things I really like to do, even though I wouldn't mind doing this one the second time around.

As to ROI, I never bothered with that in making the decision to install PV. Only after the system was in did I do the financial analysis. The fact is, ROI always has been secondary or lower on the list when my impact on the environment is the focus. The woods and meadows, lakes and wetlands, wildlife, smells and sights, peace and quiet, experiencing the cycles of life in real time, and more -- all are far more important to protect and preserve, because they are what makes my life possible, than is ROI.

In fact for the great majority of people, asking about ROI is laughable, because they have no investments, they have no savings, they have no retirement funds, and if they have anything, it is debt to fund consumption. Asking about ROI is a bait and switch argument for them, a distraction from what is important.

jebatty - Different strokes for different folks... The whole time vs. money argument is fully appreciated here. I wanted to maximize my PV array at the lowest cost, while still getting the federal and state tax credits last year. I am going to do the same this year with a DHW system to help with the hot tub. My state (NC) credits expire at the end of this year. Kudos to you for your install and adding on!

 

[5654684]

Just to bump an old thread and give you some updates on performance; here are the numbers as of today:

My system has been running since January 1, 2015. This has been 175 days. Total output has been 3.719 MWh. This works out to 21.25 kWh per day. I made 24.64 today, and as you can see, the steep drop off is due to the sun moving west of my array. My best day was back in March when I produced 34.96 kWh.

 

[jebatty]

Congratulations on your system and your accomplishment. Another breath of fresh, clean and healthy air for everyone.

 

[sgcsalsero]

Griz, can you give another update on your PV performance. Great information, thanks for all the time and effort to post.

 

[5654684]

Griz, can you give another update on your PV performance. Great information, thanks for all the time and effort to post.

So, this is my system after 366 days. Daily average is 19.68 kWh/day. If I had sold all back to the co-op, I would have a yearly benefit of $395.39. If I used all, the benefit would be $846.52. Those numbers are just based on the sell back rate and the buy rate per kWh, not counting the energy efficiency rider or the $5.25 monthly fee for the 2 way meter (renewable energy generation charge). PvWatts estimated my production at 6855 kWh/year, so 7202 was pretty good. Our weather here was pretty dry and sunny all summer, but rainy and cloudy the last 3 months of the year. It was a good year to go solar, and now that the Feds have extended the tax credit, we are planning expansions.

 

[5654684]

Total as of today 1-4-18

 

[WiscWoody]

I only use around 200 KWh of electricity a month for 9 months of the year and around 280 the other 3 months, in the summer. But I am in the north where the sun isn’t strong in the winter.... it’d be neat to put a system in and I have done quite a bit of DIY project like building my own 3 level home here and electrical work here and in my past job in facilities maintenance.... huh... I don’t know... maybe someday.

 

[jebatty]

Griz - excellent results. A 6.1kW system in my area of northern MN would be expected to produce about 6600 kWh of electricity in a shade free location.

WiscWoody - where in NW WI are you. I'm about 150 miles straight west of Duluth. Does WI have net metering? Unless you would be affected a lot with clouds by Lake Superior, a 2.2 kW system in a shade free area probably would provide on an annual basis nearly all of the energy you use. Of course, on a daily or monthly basis production is variable.