Moving forward on MN solar installation

[pleppik]

I am in Plymouth.

House is two story with SW facing profile. Layout has 11 panels on garage and 13 on 2nd story roof.
20 degree pitch to the roof. I have black roof and normally the snow melts except for the large blizzards.

Just a small shading effect on my garage from a chimney.

I'm in Minnetonka, and my configuration sounds very similar to yours. I have 8 panels on the garage facing SE, and 8 on a 3rd story roof facing SW.

Have been reviewing the posts about TenK and the snow removal issues. Great pictures on the install of the panels.

Who was your installer?

Aladdin Solar

[pleppik]

Have been thinking about installing 9.84 array of TenK panels next year under Made in Minnesota program. Seems to be a large incentive with State now paying incentives for 10 years.

Noticed the discussions about shedding snow. How is your system doing with the January snow in Minnesota?

Are panels performing as expected?

I've been posting my performance data to this thread: Comparing Production Estimates to Actual Production.

The bottom line is that my solar panels have been outperforming the installer's estimates by a huge margin (like 30%). I don't know if that's because the installer intentionally underestimated the production or what (I have been correcting for weather).

This winter we haven't much in the way of big snowfalls, just a series of 1-2" clippers. An inch or two is enough to cut solar production by 90% or more, and it's not heavy enough (or warm enough) to slide off the panels. But it is thin enough that if we get a bright sunny day and temperature in the upper 20's, it will melt off in a few hours.

Your mileage will definitely vary. I've been brushing the snow off one of my arrays, and leaving the other to melt on its own (too high to brush). Based on the relative generation of the two arrays, the one I can't reach with the brush has lost about 20% of its production due to snow cover in the months of November, December, and January. On the other hand, those are the darkest and cloudiest months of the year, so the lost production is the equivalent of just a few sunny days in June.

If your roof has a higher tilt than mine and/or faces more directly South, you will probably get more self-clearing of snow than I experience.

The TenK modules look good, and I have no complaints. I think the TenK design really helps with my partial-shade situation.

Where are you located, and have you selected an installer?

[Solarnemo]

TenK panels and snow

Yes, that was one of the things which really interested me in this product (that plus the fact that Minnesota will pay for half the cost).

The garage array pictured gets both partial shading mid to late the afternoon (mostly in winter) and dappled sun early in the morning (again, mostly in winter). I'm really interested to see if this design gives good performance under these conditions.

Have been thinking about installing 9.84 array of TenK panels next year under Made in Minnesota program. Seems to be a large incentive with State now paying incentives for 10 years.

Noticed the discussions about shedding snow. How is your system doing with the January snow in Minnesota?

Are panels performing as expected?

[flem0061]

The equipment was delivered yesterday for our 18 panel tenk system. I noticed that the racking is by SnapnRack instead of the IronRidge that was proposed. Can anyone weigh in on the differences between the two? Thanks in advance - we're southeast of St. Paul.

[ChrisOlson]

We're a few ladder rungs north of Minneapolis with 6.75 kW off-grid. Using the figures from our logging system from Sept 1, 2013 to Aug 31, 2014 our arrays produced 7,612.4 kWh, and that's DC output to the battery. PV input energy to the controllers for the same period was 7,831.7 kWh.

[specialgreen]

the design... will consist of 16 410W TenK modules for 6.56kw, . Estimated annual production is about 5,800 kWh.

Does that annual kwh seem low?
If I plug into PVWatts (http://pvwatts.nrel.gov/pvwatts.php)
- Minneapolis MN
- 6.56 kW
- Standard module (not premium)
- Roof-mount
- Azimuth:SW
... then I get 8,567 kwh/yr for a 30-degree roof.
Tilting the roof to 40 degrees adds 0.6%;
turning to SE instead of SW adds 0.4%.

Asking because I'm also in Mpls, and had been using PVWatts as an estimator.

[tfbrice]

Just to follow up: I am in Northfield, MN. We had the inspection by Xcel yesterday (7/28, 10 days after the local electrical inspection). We were told that since we are outside of the Twin Cities area we could not schedule a meter installation, rather it would be 7-10 days. Well, they came today and replaced our existing meter with a bi-directional meter and added a production meter. We are now actually sending power back into the grid. The final step will be to configure the eGauge monitoring system.

@pleppik: Has your system been brought on-line yet?

[tfbrice]

I am in the same boat. Our inspection was completed yesterday on a 21 panel tenKSolar install. I would really like to get Xcel out here but I am waiting on them to get info into their system so that I can sign the final documents for the MiM incentive and schedule the commissioning of the system. I will be following this thread with great interest.

[pleppik]

We have now passed the electrical and building inspection, and we're just waiting for Xcel Energy to install the production meter and the bidirectional meter for our home.

Xcel has a new online system this year for doing the solar paperwork, and our installer says it's broken in a hundred different ways. This does not give me confidence in Xcel's ability to do things quickly or efficiently.

I'm beginning to really appreciate just how much of the installation cost in the U.S. (or at least my corner of the country) is driven by red tape and inefficiency.

[pleppik]

Yea, big. Are those 6" square cells; those seem to be about state of the art these
days? My no name panels are 72 cells; even on the ground, I made a jig for helping
put them up myself. My 60 cell panels I can manage comfortably. Bruce Roe

I didn't really pay that much attention to the cells themselves, but let's see.

Zoom in. Enhance. Enhance. Enhance.

Cropped cell.jpg
Judging from this picture, I'd say these are either 3"x6" rectangular cells, or 6"x6" square cells with a conductor or something down the middle.

[pleppik]

Check out the TenK solar website. Not only are those panels huge with a lot of cells they are also wired in a "mesh" arrangement which provides multiple paths to keep producing even if some cells are covered with leafs.

Yes, that was one of the things which really interested me in this product (that plus the fact that Minnesota will pay for half the cost).

The garage array pictured gets both partial shading mid to late the afternoon (mostly in winter) and dappled sun early in the morning (again, mostly in winter). I'm really interested to see if this design gives good performance under these conditions.

[SunEagle]

Yea, big. Are those 6" square cells; those seem to be about state of the art these
days? My no name panels are 72 cells; even on the ground, I made a jig for helping
put them up myself. My 60 cell panels I can manage comfortably. Bruce Roe

Check out the TenK solar website. Not only are those panels huge with a lot of cells they are also wired in a "mesh" arrangement which provides multiple paths to keep producing even if some cells are covered with leafs.

[bcroe]

Size

Those are some HUGE panels!

Yea, big. Are those 6" square cells; those seem to be about state of the art these
days? My no name panels are 72 cells; even on the ground, I made a jig for helping
put them up myself. My 60 cell panels I can manage comfortably. Bruce Roe

[HX_Guy]

Those are some HUGE panels!

[pleppik]

Day 3

We had good weather for working on the roof today: cool and overcast but no rain. The installers put in a heroic 13-hour day and got the project wrapped up (mostly).

IMG_0632.jpg
Here are the first modules getting lifted onto the roof. This was the first residential installation this company has done of the 410W panels (and, I am told, only the third residential rooftop installation of these modules anywhere--these have been mostly marketed for flat roof or ground mounted systems until now). If it looks like they are trying to figure out the best way to get them on the roof, that's about right. These are at about the limit of what you can move around on a roof by hand, and the installer told me that for future installations they're going to consider renting a lift or crane for a day.

DSCN0033.jpg
The completed installation over the garage. An identical array sits on the upper-level roof off the left side of the photo, but can't be easily seen from the ground. 6.56KW total in 16 modules.

Of course the advantage of these huge modules is that once you horse them into place, there's fewer bolts to tighten, fewer cables to connect, etc. With 250W modules there would have been 26 modules to get the same capacity, and correspondingly more stuff to fuss with to complete the installation.

DSCN0034.jpg
Our wall of meters, with a blank place for the production meter which the power company will supply when we complete the final inspection. The two existing meters are for our the home and for the geothermal HVAC (which is metered separately because it gets a special rate). The power company also gets a special disconnect switch they can use to completely isolate our solar panels from the grid for safety. Even though the solar inverters are supposed to stop producing power if the grid ever goes down, the power company is understandably paranoid about keeping their linemen safe.

DSCN0036.jpg
And a third set of breakers which disconnect the solar production. All told there are three ways the system can be shut down: automatically if there's a blackout, using these breakers, and with the power company disconnect. Definitely some belt-and-suspenders going on here.

There are some minor cleanup details left to be done, and we have to pass three separate inspections (in sequence!) before we can start producing power: an electrical inspection, a building inspection, and a power company inspection. I'm told that the power company is the longest wait, and they won't even schedule it until the other two inspections are done. It's likely to be a few weeks before we're fully activated.