Newbie here doing a 20.8kW DYI install (80 sunMAX 260W panels with microinverters)

[pclausen]

I checked out IronRidge and played with their configurator for a 24 panel setup. I was a little disappointed that the cost worked out to almost $2,300 and that was before me picking up 2" pipe locally and cement, etc. I would likely also need to do quite a bit of excavating due to my slope and a 32' long run going East to West given my slope. I'm going to take some measurements over the weekend to see just what the drop is. I could build 2 12 panel ground mounts instead and have less ground work, but then I bet the cost is going to creep up over $3,000, just for the IronRidge parts. At that price, I might as well look at a pair of 12 panel single pole mounts such as these:

http://www.dpwsolar.com/index.php/tp...le-mounts-utpm

They can be had for about $2,100 a pop for the 12 panel units.

I enjoyed reading your blog. Wow, 12 hours of driving to get the cement, that is quite something. I got a Lowes and a Home Depot both within 25 minutes of my house. In fact, 2 weekends ago I went to Lowes and picked up 3 pallets (126 bags) of 80 pounders along with a pallet of gravel. One trip.



Ended up using about 110 bags for the pad.

[tyab]

For the ground mount, I would suggest taking a look at the IronRidge setup and think about 2" pipe instead of 3" pipe for that smaller setup (more holes, shallower and pipe is less heavy compared to 3" pipe). It can be installed on a North->South downgrade, you design it as if it is level and just have a lot more pipe in the ground for the North side to take account of the grade.

http://www.ironridge.com/

pick the ground mounts tab and play with the design assistant tool. You don't even have to make an account to use it.

I'm using IronRidge with 3" pipe on an 80 panel setup across 4 mounts all at different elevations due to grade of hill. I have talked to their tech support several times and they have been really helpful especially during the design phase.

http://solargroundmount.blogspot.com/ - Jack

[pclausen]

I hear you. Been meaning to cut down some of those trees for a while, especially since some of them lean more towards the shop every year it seems. What I might do for fun, is wait until the panels are up, and then cut them down one at a time, and see how it changes the production. And point taken about the micro-inverters reducing the impact in partially shaded strings. That and the fact that I can monitor each panel individually is why I went that direction.

[SunEagle]

Minimizing the amount of shade is always a good idea when it comes to a solar pv system. Remember you plan to use the micro-inverters which will help reduce the loss of production output from partially shaded string inverter installations.

I'm just saying I hope you don't remove all them trees to get a little more solar output.

[pclausen]

I'd probably go for ground mount with those 24 panels - put them out on the western edge of your lawn pointing south.
Would also make it a lot easier to clear the snow off them in the winter.

If/when you run numbers for that, make sure you change the tilt - you can have "perfect" tilt on a ground mount - not just whatever the roof has.

Yep, I would set the tilt to 32 degrees being that I'm at 37.97 lat.

Running the numbers using PVWatts, I get 9,310 kWh, which is an improvement of 2,733 kWh 20 azimuth facing array, or an improvement of over 28%. Seems like the way to go for sure.

BTW - have you looked at TOU tarrif? I don't know VA, but many people around here use time-of-use to generate only ~80% of the kwh but 100% of the $ to offset their bill.
However each POCO has different rates and rules - so that may or may not be something that can help you.

No TOU where I live. Just the same flat rate all the time.

[pclausen]

Appreciate the feedback! Yes, I think having those 24 panels on a ground mount North of the shop is not a bad idea at all. I plan to cut down those pine trees that are casting a shadow anyway, as they will also shade the main arrays in the South shop roof.

So I walked out to a spot North of the shop and took the following pics, trying to hold my camera as level as I could. Red ovals are the trees I'm cutting down.

South:



West: (notice that I'm in close proximity to the 400A shop meter base, so the run would be pretty short.



North: (very steep grade up the hill to the house)



East: (this is also a steep grade)



For perspective, here's looking due South from the house upper level bedroom window:



And SW from the same window. The yellow marking is where I was taking those other pics from and orientation I envision for the ground mount, should I go that route.



Since there is quite an upward slope to the East, what type of ground mount would be suitable?

[SunEagle]

I was also thinking about having those 24 panels on a ground mount installation North of the shop but on the East side based on ground elevation in the first picture. At least
It would be close to the other 56 panels and still have them facing South. I am not sure of the cost but IMO it might be less then putting them on the West facing side of the House.

[foo1bar]

I'd probably go for ground mount with those 24 panels - put them out on the western edge of your lawn pointing south.
Would also make it a lot easier to clear the snow off them in the winter.

If/when you run numbers for that, make sure you change the tilt - you can have "perfect" tilt on a ground mount - not just whatever the roof has.

I would guess that ground mount pointing south will be >20% better than pointing northwest or northeast like your other options.

BTW - have you looked at TOU tarrif? I don't know VA, but many people around here use time-of-use to generate only ~80% of the kwh but 100% of the $ to offset their bill.
However each POCO has different rates and rules - so that may or may not be something that can help you.

Good luck.

[J.P.M.]

It looks like the 20 deg. az. arrays will produce revenue (bill off set) at ~ $0.129/ STC. Watt, while the 200 deg. az. will produce revenue (bill offset) at ~ $0.1756/STC Watt.

Not my project, but if it was, I'd have been looking at the economics of the whole thing in terms of the levelized cost of electricity (LCOE) compared to the POCO supplied LCOE and also alternate things I could to do with the money that might have a better return over time, Not with the idea of not doing the project, just as another way of comparing costs and opportunities.

That 20 deg. az. portion might be a poorer revenue producer and/or take a longer time than other places to put the $$ or to break even at $0.129/Watt current annual revenue.

moving that array to the hose may produce more annual output, but I'd wonder if the extra considerations and complications that might be entailed would make it less cost effective.

If it was my project, considering it looks like you've got a fair amount of land, I'd add another alternate of a one array, fixed ground mount , provided it was within aesthetic and practical realities, and provided the LCOE came out less than the other LCOE's, both for the POCO power and the alternates. I can always choose to do any/all alternatives regardless of costs, but it's always nice to have the information for the decision making process.

Before I did all that, I'd be looking at the most cost effective bill off set. That off set may be less than a "get even with the POCO" scenario which, while feeling good, may not be the most cost effective system size and I wind up with lead poisoning in my foot. Just sayin'.

But, whatever I did, I'd be making sure it was within whatever cost constraints that life cycle costing methods using reasonable and realistic assumptions might require.

Good luck.

[pclausen]

I thought about that, but as you can see from the below pic, the house only has a tiny section with a Southern exposure, and there is a tree South of it.



I do have quite a bit of West facing roofing. Here's what those numbers look like:



So having those 24 panels on a West facing roof only gives me an extra 600kWh per year, vs. the North facing roof. That's less than a weeks worth of usage for me. Probably not worth the effort and I'm not sure I'd want to tear into that 19 year old asphalt roof, vs. the metal shop roof.

[emartin00]

Personally I think it would be much easier to just put the last 24 panels on the roof of the house.

[pclausen]

Hey guys,

I live in Central Virginia and have decided to go all in on a grid tied solar system. VA does not allow residential systems to be any larger than 20kW, so that is the size I'm going with, which will almost meet my annual energy needs. Here's my 2015 and 2016 usage to date:



I have been an avid fan of Ubiquiti products for a number of years and have a lot of their UniFi gear deployed in my house (Wifi Access Points, Switches, Gateway and central management). So I was exited when they released their sunMAX product line at a price of about $1,50 per watt (includes everything but the installation itself).

I spent the last few months prepping. I originally had 2 400A services on my property, one feeding my house (with 2 200A panels) and the other feeding my shop building with a single 200A panel, but with provisions for adding in a 2nd 200A panel in the future if I added a large welder or something along those lines. Spent quite a bit of time talking to my POCO (CVEC) about my solar plans, and they would not let my install the panels on my shop roof and then apply the credit from the power generated there my residence which uses the most power by far (above spreadsheet is just the house). So I had them drop the service from the pole that was feeding the shop, and I dug up the 3 500 MCM cables the 200 ft back to the shop meter base and then dug a new trench up to the house, to tie into that service.

It was a lot of hard work, but that part is finally done. Here's a shot of the run from the shop to the house, and you can also see the original run going over to the power pole running to the left.



At the house, the POCO dropped off a new meter base for me, and I then purchased and installed a 400A fused disconnect, and a 400A automatic transfer switch for the 2 x 200A service into the house. Here's a shot of that work being completed and me getting ready to pour a pad for my generator. My girls are 4 and 5, so as you can see, those are some decent size panels. It was a challenge to mount those solo and run the wiring, most of which was 300 MCM Cu!



Everything has been approved by the AHJ so far and the POCO has also signed off on my 20kW system. All the parts are ordered and should be arriving sometime next week, at which point I'll begin the install. Here's a schematic of the overall system:



The diagram is not 100% accurate in that my original plan had me doing 60 panels for the 15kW system, but I changed my mind and upped it to a 80 panel 20kW system. I made this decision after running PVWatts and discovering that putting 20 panels on my North facing shop roof (12:4 pitch or 18.4 degree angle) would actually generate a pretty decent amount, and then me to the point of being able to produce all the energy I am consuming.

I did 3 scenarios in PVWatts as seen below:



In all 3 scenarios, I have 56 panels on the South facing shop roof, plus an additional 24 panels in different configurations, going from least efficient to most.

Scenario 1 has the 24 panels at 20 degrees azimuth, which generate 6,700 kWh annually.

Scenario 2 has the 24 panels at 180 degrees azimuth, which generate 9,450 kWh annually.

Scenario 3 has the 24 panels on a 2 axis tracker, which generate 12,900 kWh annually.

Given the cost of a 2 axis tracker that can hold 24 60 cell panels, I'm pretty much ruling out option 3. But I'm torn between option 1 and 2. Option 1 is the easiest of course, but option 2 would not be too bad. It would basically involve me building a car-port like structure with a single shed roof leaning directly to the South with an angle of about 31.5 degrees (I'm at 37.33). The PSWatts calculation above shows it at 18.4 degrees like the shop, but it does not change that much. I have plenty of space, no shade to speak of.

So is it worth building the car-port to get that extra 2,750 kWh of annual production? I figure I can do it for around $1,000, so it would pay of itself in 3-4 years, and I would have a place to park my trailer, and or store some of my tractor implements that don't fit in the shop building at the moment.

And finally, there seems to be very little love for sunMAX on this forum. I hope I didn't make a mistake going with their product, but $28k delivered for a 20kW system seemed like a really good deal, and I have not really heard anything bad about the sunMAX product and I have had great luck with the rest of their products.

P.S. 4 years ago, I installed a Trane XL20i heat pump with a 20 SEER rating. It contains 2 compressors, so for stage one heating or cooling, it only runs the smaller one. This helped a lot with my electric bill. When they installed it, they also did an assessment of the house overall and found level of insulation, doors, windows, etc, to up to par with little to be gained. I have a pond with a pump, a pool with a pump, and servers and network equipment in the basement that runs most of the time that I can't really do anything about. Almost all my lights are LED at this time.

I do have a sense on order (sense.com), which will allow me to identify all my power consumers to see if there is anything else I can do to cut my consumption further. But the house is large and I live with 4 females, so there is only so much I can do.

Thanks!

Peter