Solar Scams

A dear friend of mine, knowing of my interest in solar power generation, asked me about an emergency power backup system being sold by Solutions From Science [sic]. She was quite interested in this offering because it was a seemingly reasonable alternative to a gas generator. In particular, she was attracted by the elimination of the storage of gas and the fumes from a running generator.

I took a look at the system which was being offered and sent her the following in an email:

Hi Friend,

I'm glad your forwarded this link to me as I was quite curious.

Executive Summary

It would be a waste of money and you would not be happy with this system's performance.

Analysis

This is basically a very low power solar panel (90 watts, barely enough to power a light bulb when in full sunlight). This panel is going to charge a battery capable of providing 1,800 watts.

They don't say how long that battery can provide those 1,800 watts which is one concern. Normally, a company will specify a battery's capacity in terms of watt-hours, or how many watts it can provide for how many hours. If we guess that the battery can provide 1,800 watts for an hour before it is completely depleted then we can estimate how long it can power certain appliances:

• A 22 cu. ft. Energy Star refrigerator typically uses 500 kWh per year, or 1.37 kWh per day. With 1,800 watt-hours available that refrigerator would run for about 31 hours.
• A washing machine uses anywhere from 1.9 kWh to 4.5 kWh per load. So the battery wouldn't even be able to do one load.

Actually, though, it's very bad to completely deplete a battery. Usually, a battery should never be discharged below 20%. I doubt that they're being honest about the battery capacity.

One other interesting question is: How long would it take to recharge the battery? Let's guess that we experience a power outage in the winter (since they seem to inject fear of power loss in a winter storm) but that there's no storm or even a single cloud in the sky. The normal 'peak' sun hours in winter is usually given as 4 hours. Let's say that we've used the maximum recommended capacity of the battery (80%) which means we need to put back into the battery a fresh 1,440 watt-hours. The efficiency of a charge controller is usually about 85%. So let's calculate how many hours it would take to recharge the battery:

• total hours to recharge = watt-hours required to charge the battery / (output of the solar panel x efficiency)
• total hours to recharge = 1440 / (90 x 0.85)
• total hours to recharge = 18.8 hours

• total days to recharge = 18.8 / 4
• total days to recharge = 4.7 days

So this says that at best you would have to charge that battery for five days just to do one load of wash.

This is also saying that the best power you could possibly get out of this system in the winter would be a measly 306 watts per day! This is barely enough to provide light.

This system is clearly a scam. You would probably be better off picking up a small diesel generator and barrel of fuel.

I hope these words are helpful.

Mike

It's disgusting how some people prey on other's fears.

$30!

Just got our September electricity bill -- $30.54!

Energy Production Report

The electric bill for April arrived last week and I'm pleased to announce that the bottom line was...

$37

This was about a third of what it was a year ago!

While I'm excited about the latest energy usage I'd like to say a few words about Tigo Energy. If you've read my earlier posts you will recall that Tigo provides small, individual micro-controllers which optimize the voltage output of each panel. In essence, this prevents a poorly performing panel from pulling down an entire series.

I cannot recommend Tigo highly enough. The product works as advertised and the company worked hard to insure that my 'bleeding edge' system had tender-loving care. Tigo has even automatically uploaded firmware updates to the LMUs increasing optimizer efficiency. The monitoring website gives high-level graphical information giving an instant view of system production. One can also download incredibly detailed information, by the second and down to the individual panel, suitable for low-level analysis using your favorite spreadsheet.

The weather has been too inconsistent to perform a thorough analysis of how the overall system works with and without the optimizers enabled. Later this year, when we have a forecast of several cloudless days, I will alternate days with the optimizers enabled and disabled to see if the boost in efficiency can be better established.

Gateway Placement & Analysis Tools

As with any antenna, the placement of the Tigo gateway is important. Things like aluminum soffit (commonly used for the ceiling of outdoor patios) and facia, metal conduits, and electrical wiring can make effective RF shields or introduce enough RF noise as to interfere with proper gateway operation.

Initially, I had hoped to place the Tigo gateway inside a portion of the roof facing towards the solar module array, above the plane of the array (understanding that the LMUs are below the plane of the array). Unfortunately, the combination of facia, conduit, electrical wiring and the relationship of the gateway to the plane of the array resulted in poor gateway communication with each LMU.

Tigo's website is a perfect tool for diagnosing such communication problems. On the right is an example of the Tigo 'Summary' page for my installation. Note the two panels showing in gray. Gray indicates a some kind of module failure; a communication failure in this case. At the bottom left of the page is a tool for scrolling through a day's worth of solar production data. If when dragging that scroller one sees frequent gray panels a communications problem is the likely culprit.

Tigo's website also provides extremely detailed information on an 'Advanced' page. This data is downloadable in CSV format, suitable for importing into your favorite spreadsheet, and can be as fine as one sample per second. Evaluating the downloaded data by looking for gaps in reported data can assist in the diagnosis of panel problems. If a single panel's LMU never reports data then there may be a panel problem. One can then report this to their installer so that the search for the problem is simplified.

What one wants, of course, is a presentation showing all green panels with relatively similar wattage amounts, as shown to the right. Data for past dates can be brought up by clicking on the calendar control at the bottom left and choosing the desired data. The day's recorded data can be 'played' by pressing the 'play' button. And the total day's accumulated production can be seen at the bottom right.

In my case, gateway placement was causing communications issues so I tried different placements over a few days. In consultation with Tigo's Stuart Davis, we identified a number of candidate placements. The optimum location would be within the attic just below the top row of panels and generally facing towards all panels. Unfortunately, that would be a difficult location to get to. Ultimately, I settled on a location about 25 feet in front of and two feet up from the bottom of the array. The gateway will be mounted on a short pole from the side of the house and face directly towards the array.

With this setup, things are working extremely well, and, on sunny days, I am seeing about 35kWh of production. I expect this number to rise as the days get longer.

Our March Rocky Mountain Power bill was, once again, one half of what it had been a year ago.

Production Analysis

The Tigo web site has several other important tools for analyzing power production. The 'Energy' page can show the performance of the entire array or individual solar modules. On the right is a daily snapshot hour-by-hour of my system for April 7th.

On the left is a weekly snapshot showing day-by-day production from April 3rd for seven days. Clearly, the 5th and 6th were cloudy days with low production, but the 8th was a terrific day for production.

It's Alive!

Monday, March 22nd

I received a call from Stuart Davis, one of my heroes at Tigo, telling me that yes, they had indeed modified the connectors on the LMU based on installer feedback. He said he would overnight a crimper and some new connectors.

While I was talking with Stuart, he mentioned that their system was seeing power from all of the modules! I was surprised, though I shouldn't have been — it isn't necessary for the panels to actually be feeding power to an inverter in order for the LMUs to be reporting panel performance.

Tuesday, March 23rd

The crimper and connectors arrived from Tigo in the early afternoon. Anxiously, I ran the scissor lift back to the panels, gathered some tools and cable ties, and proceeded to:

1. replace the connectors on the home-run cables,
2. connect the home-run cables to the series feeds,
3. re-energize the DC disconnect,
4. re-energize the AC disconnect, and
5. watch the inverter expectantly.

SUCCESS!

Power to the inverter!

SUCCESS!

Power being reported by the Tigo website!

Being on a roll, I then proceeded to cable tie everything nicely so there were no more loose, dangling cables.

The Big Day™: LMU Swap-out

March 20th, 2010

Finally, the forces of the universe converge (i.e. a Saturday with excellent (i.e. non-freezing) weather when my co-installer (i.e. my son) is available) and a swap out of the LMUs can proceed.

My very kind neighbor has once again loaned me his scissor lift. My son and I evaluate the situation and decide that it would be best to remove all solar modules from the roof rather than try to perform the LMU swap on the roof. So that's what we did: started with the bottom row, loosened the restraining bolts, and lowered panels to the patio three to five at a time. This took about three hours and we broke for lunch.

In order to prevent theft while off to lunch at Astro Burger, I pulled my Smart car into the space between the house and the garage so no one could get through the gate and to the panels. There's little theft in our neighborhood, but I wasn't willing to take any chances.

Once all panels were at ground level, and before we swapped the LMUs, we discussed how best to replace the panels on the roof. The idea was that we could sort the panels so that the desired panels would be front-most in each stack ready for the swap and then lifting to the roof.

We went round-and-round: Should we replace the panels one row at a time from the top down? Should we place the panels starting at the bottom in a diagonal pattern giving a base to hold the higher panels during mounting? Or should we place panels in series order?

We made our choice, sorted the panels, and it didn't matter anyway since we changed our approach. So the panels were all out of order! It would have been better to have left them in the order we removed them from the roof. No matter. We bravely motored on.

Three panels were pulled out of the stacks at a time, I disconnected and removed the old LMUs (with my brilliant clutch drill and hex wrench), my son clipped on the new LMUs, and I connected the LMU wiring to the panels. Then Jackie (my sweetheart) helped test each panel for proper voltage output (~50VDC), I strategically placed some UV-resistant cable tie mounts on the module framing, and back up to the roof we'd go.

Once we got an entire series of 8 panels re-installed we'd once again check voltages, this time looking for something in the range of 384VDC.

It was about 5 PM when we placed the last panel and sent my son back to his family. I then prepared to reconnect each series to the home-run cables to the inverter:

• DC disconnect disconnected: check!
• AC disconnect disconnected: check!
• Cable ends not laying in water in gutters: check!
• Visual inspection: check!

"It's ready to connect!" I say to myself.

A quick trip up on the scissor lift and I grab a feed from the last LMU in the first series and the matching cable from the home-run and... Huh? They don't match!

The two cables in the middle should look the same, as should the two cables on the outsides. Clearly, the connector types have changed with the new LMUs. Previously they used Tyco connectors and now they are using MC4 connectors. Well, no power to the inverter for a day or two I guess.

I dash off an email to Tigo hoping they will, once again, be able to help.

In Search of a 3mm Allen Key

In preparation for the Big Day™ (when the MMU/LMU swap-out would take place), I ran down to the local Home Depot to see if I could find a 3mm allen key (hex wrench).

The original LMUs are fastened to the frame of the solar modules with hex head bolts. Recalling how much time it took to perform the original, manual installation with an L-shaped hex wrench, I came up with a brilliant idea (if I say so myself): "I'll get a new 3mm hex wrench and cut off the end of the 'L' so that I can put it into my clutched drill and let a little electricity remove the old bolts."

I already had a very nice metric hex wrench set (a gift from my oldest son) but I didn't want to ruin the set by destroying one of its members. So it was off to the old Home Depot. Unfortunately, I could only find hex wrenches in sets (I miss the old hardware store where one could get just what one needed!) — and it wasn't worth running all over town in the vain hope of finding a single hex wrench of the desired size — so now I have two sets of metric hex wrenches.

But at least I have my drill all ready to go and I can look forward to a rapid disassembly of the modules.

There was no reason to delay enabling the new Tigo MMU and gateway so I temporarily placed the new MMU in our laundry room (which has a convenient ethernet connection), temporarily installed the gateway looking out the laundry room window towards the module array, connected the MMU to the ethernet, powered things up, and insured that there was an Internet connection.

Of course, I didn't not expect the panels to report anything yet because the LMUs had not yet been replaced.

Good News & Best Laid Plans

It's now mid-February and two important things have happened:

• We've received our first full-month Rocky Mountain Power (RMP) utility bill since the installation of our PV system went on-line, and
• Tigo has sent the latest version of their MMU & LMUs for replacement on the solar modules.

Our RMP bill was half of what it was a year ago!

Granted, weather conditions have a dramatic affect on power usage, but this type of reduction is a very hopeful sign.

As mentioned in an earlier posting, Tigo had offered to send out the "latest version" of their MMU and LMUs for a wholesale replacement of those which I'd installed in December. I took them up on this offer in that the earlier equipment was some of the first to come off of their new production line and the effort required to get it all working properly would certainly be greater than just replacing everything. Plus, the latest version of their LMUs promised better efficiencies in power production.

Now to schedule a day when my co-installer (my son) and I could perform the swap. It had to be a Saturday since my son was out-of-town every week for five weeks. We picked a week in February and set our plans.

Three days before our planned re-installation: The weather looks like it will be great with clear skies and temperatures in the 40°Fs.

Two days before our planned re-installation: The weather is starting to look iffy but perhaps it will still prove acceptable. I also prepped everything by pulling the new equipment out of the boxes and getting it staged for rapid assembly once the swap-out started. It was fortunate I did the prep because I discovered that the new LMUs mounted with pressure clips instead of screw clamps AND THERE WERE NO CLIPS INCLUDED IN THE SHIPMENT!

A quick call to Tigo and a bunch of clips were shipped overnight. What a great bunch of guys! No, "Well, I'll have to get back to you on that." Just a, "I'm so sorry! You'll have them tomorrow."

One day before our planned re-installation: The weather is clearly deteriorating and it looks like we're going to have to put things off.

The day of the planned re-installation: Rain! No way I'm getting up on the roof in rain!

Meanwhile, the existing setup (i.e. without the Tigo system fully operational) was producing lovely amounts of electricity, especially on sunny days.

Shocking Developments

An exciting day!

Rocky Mountain Power arrived in just a couple of days of my request and performed the meter swap. I was so excited that I forgot to take pictures.

The technician was very careful. The safety considerations were obviously important. He wore heavy gloves and a full face shield. Where previously he would have just broken the meter seal and yanked the old meter off by hand, he now employed a very heavy duty plastic tube-like device which surrounds the meter and clamps on, and, after a slight tug, removes the old meter. The new meter is installed using the same tool.

He explained that they do this now because so many meters have exploded because of some short that occurs when removing or installing the meter.

Of course, I'm just standing there watching with no face shield or other protective gear.

The longest part of this process was spent in the RMP truck programming the new 'smart' meter.

The new meter, among other things, records a) power sucked from the utility (consumed), and b) power pushed to the utility (produced). Our new power bill will show these two numbers, calculate the difference, and bill us for that difference.

So, if in a month we consume 70 kWh and produce 50 kWh then we will have to pay for 20 kWh. If we produce more in a month than we consume then it gets 'banked' for the next month. Anything still banked at the end of March of each year simply disappears. Since our intention was to minimize peak usage we are unlikely to have anything banked at the end of March.

The new meter also has an animated display and shows the two important numbers. If you look closely at the area highlighted in yellow you'll see a bar with an arrow pointing to the left. That's a good sign! It means our solar modules are producing more electricity than we are consuming and that the extra is being fed back into the utility. The bar animates and the faster it runs the more power is feeding in whatever direction.

Failure to Communicate

Meanwhile, it's back to figuring out why I'm 1) not seeing power being reported at the Tigo web site, and 2) not seeing any power at the inverter DC input.

Let's just make a long story less long.

December

We were never able to exactly identify the reason why the Tigo MMU/gateway was unable to communicate with the LMUs on each of the solar modules. I did discover that powering down the MMU would cause DC to appear at the inverter. This was somewhat of a surprise to me in that the individual LMUs moderate the voltage coming from the solar module to which it is attached and I had expected that failure to communicate would result in zero VDC. Tigo explained that the LMUs fall-back to just passing through the unmodified voltage in the case of a communication failure; makes perfect sense.

January

Once again I checked the continuity of the cable which runs between the MMU and the gateway. With Tigo's help I also checked the voltage inside the gateway and inspected the LEDs. Tigo sent out a new gateway. No change. Tigo sent out a new gateway cable. No change. Remember, this is all bleeding edge equipment so challenges like this were expected. In no way was I frustrated by these communication issues—the only anxiety I felt was that we could in fact get the Tigo Maximizers working.

February

So Tigo sent out replacements for everything: new MMU, new gateway, and 24 new LMUs!

I hate to keep you in suspense, but since this was still Winter and I despise working in sub-freezing weather I postponed getting back up on the roof until the daytime temperatures were going to be at least in the upper 40°F range.

Dotting the T's with Rocky Mountain Power

Now that the panels have been mounted, the inverter installed, conduit run, disconnect installed, and the DC and AC wiring completed it's time to get Draper City to send out their building inspector for a final electrical inspection and Rocky Mountain Power (RMP) out to swap the meter and get this system producing!

Draper City is very responsive and an inspection was scheduled for the next day. The inspection was mostly chewing the fat about solar, how it's an 'emerging' technology, how nice the panels look and what the pay-back was expected to be. If Vince and I hadn't opened up the main service panel and opened the cover of the AC disconnect I don't think they would have gotten a look-see. Sorta reminded me of a guided tour.

I had previously (that is, months ago) completed and mailed in to Rocky Mountain Power the Interconnection Agreement for Utah. I'd called in to verify that they had received it and was instructed to call back when the system was ready for inspection. So I made the call and asked for an inspection. Before RMP could inspect and do the meter-swap they required a copy of the city building inspector's report to be mailed in—and they apologized for not following-up by sending me the packet of information which would have given me detailed instructions on what to do as the power-up day approached. Also, a separate inspection visit by RMP would not be required if I provided photographs showing that the 'signage' at the main service panel met their requirements.

Rocky Mountain Power has an office only a couple of miles away so it was easy to run over a copy of the city inspection approval and photos of the signage. Everyone there pretty much wears heavy work boots and wears suspenders. They promised to get the installer scheduled within the next two weeks Since net-metering is an 'emerging' technology they warned me that a meter might have to be ordered and that only properly trained technicians could perform the install. This kind of talk made me nervous since I needed to have the system functional before the end of the year to guarantee that we could take the federal tax credit for 2009—who knows what might happen to that credit if it slips a year! I mentioned this concern to them and subtly reminded them it was they who'd jeopardized the schedule by not sending out the preparatory material.

One more trip was made to the RMP office to drop off the completed and signed the net metering agreement, the one they had neglected to send as part of the preparatory material.

Oh, and one other thing: we notified our home owners insurance carrier that we had installed the solar equipment and made sure our coverage was increased as needed.

Catching Up: Inverter & Wiring Installation

The Tigo folks, in particular Daniel and Stuart, have gone above and beyond in helping to figure out why there did not seem to be any communication between the MMU and the gateway. We spent a bit of time on the phone with the cover off of the gateway box, prodding and poking and looking at LEDs to see if we could figure out what might be wrong.

Meanwhile, Vince Landvatter and his brother, both master electricians, came by and we got the inverter mounted, the high-voltage DC wiring run, the AC feed to the service panel installed, the AC disconnect mounted, and the heavy-duty Tigo MMU box set up.

The inverter, a Fronius IG Plus 5.0, is mounted inside our garage, thus keeping it out of the elements and in a more moderate climate. Our outdoor temperatures range from just above 0°F to 110°F over the year. Also, the most convenient locations outdoors would be in full sun, which is something I wanted to avoid. This indoor location is just around the corner from the service panel.

Once the electricians got the Fronius mounted, I popped it open (the bottom part that is), pulled off the cover panel, removed the insulating sheets, and pulled the slugs Fronius had pre-installed in the fuse holders. DON'T FORGET TO DO THIS BEFORE THE DC FEEDS FROM THE MODULE SERIES ARE HOOKED UP!

The outdoor installation includes the main service panel, the AC disconnect, a place for the Tigo MMU, and, very importantly, signage.

The small box in the middle is the AC disconnect. It must be located very near (i.e. adjacent to) the main service panel so that a utility technician can pull the disconnect should maintenance work be required in the area. In this case, the AC disconnect is redundant (but required by the utility for safety) since the Fronius will automatically shut down the AC feed should it discover no AC on the utility side of things.

The beige box in the right is where the Tigo MMU goes. The flexible conduit coming out of the bottom of that box and snaking upwards is for the gateway cable. The flexible conduit coming out of the bottom of the Tigo box and snaking to the left is for the ethernet cable.

The beige box just below the AC disconnect is the network interface box. Formerly used by the telephone company, I had the foresight when building the house to pull four Cat 5e ethernet cables from the utility room. This was very convenient for use by the Tigo MMU to connect to the Internet and Tigo's monitoring web site.

The electricians got everything wired up so all we need now is for Rocky Mountain Power to come and inspect things. Well, almost ready...

One last thing to do: check the module series voltages at the inverter. And it's a good thing I did! And it's a good thing I pulled the fuse slugs earlier! Because one of the module series had been wired in reverse. A quick trip to the j-box on the roof and everything was back on track.

Catching Up: Mid-December

First, let me apologize for not updating my blog for several months. Life is busy and while the path may have been a bit rocky, the ultimate outcome of this project has been very satisfying.

When we last left the story, the day was too long in the tooth to do any MMU/LMU testing. The next morning, after sunrise, I was back outside with my handy Fluke 12 Multimeter checking the string voltages. All three strings were reporting full voltage of around 385 VDC! I decided to keep an eye on things and move ahead with getting the Tigo MMU up and running. Doing so would allow me to monitor each individual panel performance on the Tigo web site.

The MMU connects to the Internet in order to send data to Tigo's data center. There is a 'gateway' box connected to the MMU. This gateway communicates with the LMUs wirelessly. It allows the MMU to collect performance data and to control the power output of each module.

The Tigo gateway is connected directly to the MMU by a small, four conductor cable. The cable is quite long and allows great flexibility in the placement of the gateway, which I was to learn later was very important.

Here's how it all fits together, communication-wise:

I temporarily installed the MMU in our laundry room, which is just through the wall from our main electrical service panel and with a convenient ethernet nearby. I placed the gateway in the window with the face of the gateway aiming towards the array, connected the ethernet cable, and plugged in the power.

Things are looking good: The MMU 'boots' up. I play with the simple menu system and discover the IP address and see that it's connected to the Internet. Then it's a quick trip to the Tigo web page showing my system and...

...everything is gray. No information coming from the LMUs! Hmmm.

In the meantime, the electricians have a job to do in Deer Valley and I must wait a couple of days before they can come and get the inverter mounted, the high-voltage DC wiring run to the inverter, the AC feed to the main service panel, the outside AC disconnect installed, and various other odds and ends.

Panel Installation, Part 2

The Next Morning

Early the next morning we were off to Nuts & Bolts Supply who could supply us with the proper stainless hardware, then back home to replace those 42 mid-clips and bolts which, as you have guessed by now, required sliding everything off, replacing the bolts, and sliding everything back on. The new wrinkle this time was that over the night moisture had condensed on the rails, in the track, and had frozen. It took some effort to get the old bolts off.

Things started to move pretty smoothly. A neighbor had very kindly loaned us a scissor lift which made the job oh so much easier.  Once we got the first nine panels in place we tested the 'A' string with a voltmeter. The meter read a very pleasing 387 VDC!

Note that it is very important to use a proper torque wrench when tightening the end-clip and mid-clip bolts. Exceeding the recommended torque will easily damage the panels by cracking the tempered glass. It's also critical to avoid damage the back of the panels since it consists of a thin coating over the back of the individual cells and scratching of that coating would be a serious matter.

As each string of 8 panels was completed we tested the output voltage to make sure we were getting the desired output. We finished mounting the panels just as the sun set (and things started to get really cold) and it was not possible to test the final string since there was no longer adequate light.

Putting that last panel up was very satisfying. I tried to give my son a hug, he went on his way, and I cleaned up all of the cardboard from the panels while collecting the serial number stickers for my records.

The next morning, after the sun came up, I went out and measured the voltage of the final 'C' string and double-checked the 'B' and 'A' strings.  'C' and 'A' was fine but 'B' was measuring only 334 VDC, indicating that one panel was not producing. Since I was getting some voltage I concluded that the Tigo Maximizers were properly wired to one another. The problem had to be either a bad connection between one panel's output into its Tigo Maximizer or a Maximizer was flaky.

The best way to identify the problem was by using the Tigo MMU (Maximizer Management Unit). Tigo had already set up my account at their web site so that once I hooked up the MMU to my Internet service I could go to that web site and see how each panel was performing.

There was some confusion on my part, mostly due to inadequate documentation of the MMU and how the Tigo products worked — but this was a brand new product and I had expected some 'bleeding' edge experiences along the way.

The installation manual for the MMU did not explain how to hook up the sensor/gateway cable. The sensor/gateway is a small box that wirelessly communicates with the 24 Tigo Maximizers (LMUs) which we had earlier mounted to the back of each solar module. I dashed off an email to James Bickford at Tigo and very quickly had a Tigo engineer on the phone helping me get things set up.  The engineer also explained that it was not necessary for the solar modules to be connected to an inverter in order to determine how each module was performing.

After some initial miscommunication, I got the sensor/gateway all cabled up, the MMU connected to the home's ethernet, and powered up. By this time the sun was going down and it was futile to see if there was any output coming form the panels.

Panel Installation

We hired a couple of roofers to mount the rails. They did a fine job and the cost was reasonable.

The key when installing the rails is to insure that the L-feet are firmly lagged into the trusses.  Roofers are good at that, though one does end up having a few extra holes in the roof — nicely sealed, of course, or, in roofer-speak, 'gooped'. Chalk-lines helped keep things aligned.

The rails are mounted horizontally so that they will support the solar modules, which are 'portrait' oriented: the longest dimension of the module is vertical. The L-feet are no more than 48" apart.

The weather was starting to get cold. Because the wires from each Tigo Maximizer run between the panels (as shown in the previous post) we put adhesive cable tie holders at strategic locations on each module. It was so cold that evening that the adhesive wouldn't stick so I had to warm up the aluminum frame a bit and slap on the cable tie holder. It took a couple of hours.

A few days later my son and I started mounting panels.  Earlier in the project I was a bit reluctant to scramble around on the roof but the rails made getting around a lot easier. First thing was to slide the mounting bolts and clips into the track of each rail: 42 mid-clips and bolts, 12 end-clips and bolts, and six grounding straps over the rail splices.

We forgot the grounding wire clips! Slide off about half the clips and bolts, slide on the grounding wire clips and slide back on the other clips and bolts.  Ready.

We mounted the first panel. Almost. The end clips went on just fine and held the panel pretty firmly but we were anxious to get the other side of the panel secured. It would not be good if the panel came loose and slid down the roof. That's when we discovered that the 2-1/4" stainless bolts used to secure the mid-clips were too short! Big mistake by Wholesale Solar! We needed 2-1/2" bolts! So it was a mad dash off to the local hardware store and pick up a bag of 50 bolts.

Slide off 42 mid-clips and bolts, six end clips and bolts, the six grounding wire clips, and the six grounding straps.  Replace the mid-clip bolts and slide on 42 mid-clips and bolts, six end clips and bolts, and the six grounding wire clips.  Forgot the six grounding straps.  Slide, rinse, repeat.

We mounted the two panels immediately below the original panel, connecting the Tigo maximizer cables, and called it a day.

During the evening, as I was checking and double-checking everything, I realized that the new 2-1/2" bolts we had installed were galvanized, not stainless steel. This was not good — the galvanized hardware would have a galvanic reaction to the aluminum rails causing the metal to degrade. Sigh.

Tigo Maximizers & Module Preparation

Tigo Maximizers

Through some heroic efforts on the part of Tigo Energy, DC Power Systems, and Affordable Solar, I was able to acquire 24 ea. Tigo Module Maximizers (MM-ES060V300W-4RL), 1 ea. Module Management Unit (MU-ESW), 1 ea. wireless transceiver (which communicates with the Maximizers), and some odds and ends.

As mentioned in an earlier post, there is one Maximizer for each solar module.  In fact, the Maximizer attaches to the back of the module.  Its purpose is to balance the DC output of the panel in order to reduce the effect of shading and other module inconsistencies on the whole string of modules.  Without the Maximizer, one shaded panel would seriously degrade the production of the entire string.

The Tigo Maximizer product is brand new and is only now becoming available to the U.S. solar PV market.  Their products will initially be available through two distributors: AEE Solar and DC Power Systems.

Because AEE Solar has a local distributor, I originally attempted to work through them in acquiring this brand new Tigo product.  Unfortunately, they were uninterested.  DC Power Systems, though, were very anxious to help get me the Maximizers in time to meet my deadline (of being on-line by EOY).

I cannot say enough positive about the fine folks at Tigo Energy and, in particular, their new Marketing Manager, James Bickford!  James has tirelessly pushed internally and externally to help me acquire their Maximizers in time.  James has called and emailed numerous times to insure that things were 'in motion' and, once I'd received the product, to make sure any questions or issues I might have were being addressed.

Kudos to Tigo Energy, James Bickford and many others at Tigo Energy, DC Power Systems, and Affordable Solar, a retailer for DC Power Systems.

Module Preparation

Each Tigo Maximizer comes pre-attached to a mounting plate with a clamping assembly along two edges.  The intention is to loosen the clamps, place the maximizer in the corner of the solar module, and tighten the clamps onto the framing of the module.

Unfortunately, the Sanyo modules have a frame edge to which the Maximizer can be clamped only along one edge.  Single-edge clamping is inadequate inasmuch as any vibration at all causes the clamp to loosen.  Our solution was to drill two holes in the frame edge and then directly mount the Maximizer to the Sanyo frame:

 

Of course, it is important to place the Maximizer in one of the corners adjacent to the cable connections of the solar module.

Note that we waited to connect the cables from the module to the Maximizer until just before module installation.  Also, some Maximizers were attached to the left of the panel connection and some to the right.  This was done so that the Maximizer cables could best connect to the next and previous Maximizer in the series according to the following diagram:

Mounting Rail Reprise

For mounting the solar modules onto the roof I used Ironridge Solar Mount rails.  These are heavy-duty aluminum rails with channels into which bolts are inserted for the L-shaped mounts and the module clips, one channel for each:

Ironridge Solar Roof Mount System Rail Cross-section

The channel on the top is used for inserting bolts for:

• solar module mounting clips
• grounding straps straddling joints in the rails
• grounding wire clips for running the grounding wire from rail to rail and to groung

The channel on the side at the bottom is used for attaching to the L-mount which is then lagged into the roof.

Since this is aluminum it is very important to use stainless hardware.  If galvanized (zinc-plated steel) bolts, washers, etc. are used then a galvanic reaction will occur and the aluminum will be weakened.

So far so good.

Attaching the rails to the roof was straightforward:

• locate the trusses
• lay down chalk lines
• pre-drill holes for the lag screws
• goop up the lag screws and the bottom of an L-mount
• screw the L-mount into the truss
• slide the mounting bolts into the lower channel of a rail
• line up mounting bolts with the L-mount and insert
• apply the washer, if required, and attach the nut
• tighten with a torque wrench according to specifications

This part of the mounting was pretty much trouble-free.  Placing the panels was an 'experience'.

Solar Modules & Inverter Arrive

Parts start to arrive!  First in was a palette of panels:

24 Sanyo HIT Power N 210N/HIP-210NKHA5 Solar Modules

Next up, the inverter:

Fronius IG Plus 5.0

And some miscellaneous hardware:

Miscellaneous Hardware

The miscellaneous hardware includes the AC disconnect, fuses, grounding straps, mounting clips, etc.  [The rails had actually arrived after the panels, inverter and miscellaneous hardware, but they were discussed in the previous post.]

All of these components, including the rails, were ordered from Wholesale Solar.  The folks at Wholesale Solar were very helpful and their prices are mostly excellent, but you must know what you want — n00bs are likely to end up with the wrong equipment.

Be careful!  Two examples:

• When asking for my first quote I informed Wholesale Solar that I would have 3 strings of 8 Sanyo modules and "appropriate rails" and explained the arrangement of the modules.  The rails they proposed would work well for an arrangement of 3 rows of 8 modules, but it would not work well for the arrangement I described for them: 1 row of 9 modules, 1 row of 8, and 1 of 7.  
• Their price on the solar modules, inverter and rails were very competitive, but their prices for other components such as fuses, disconnects, and cables were actually higher than MSRP.  Even though I pointed out such discrepancies to them and they promised to check into it there was no adjustment made and I eliminated some of those components in favor of purchasing them locally.

So always check things over carefully, regardless of from whom you may purchase the various pieces parts.

Rail Installation

The rails upon which the solar modules will be mounted were installed this week.  Here is the before:

And here is the after:

The rails are heavy duty aluminum.  L-shaped mounts attach to the roof every 4 feet.  The L-feet are attached to the roof by lag screw driven into a truss.  Sealant is applied to the lag screw and to the bottom of each L.  Altogether, it took about 5 hours to install the rails with two roofers, one rail assemblyman (me), and one 'supervisor'.  (That's a 40° roof!  There was no way I was going to get up there.

The conduit for the DC power leads will run just under the edge of the roof in the soffit.

Panel Optimization Part 3

Last week, while in the San Francisco Bay area, I was able to stop by the Tigo Energy offices in Los Gatos, CA and visit with their very pleasant marketing manager and ask many questions about the Tigo Energy Module Maximizer (EMM)

The EMM is a very simple device which clip on the back of each solar module.  The power leads of the solar module are connected to the EMM.  Separate, and different, leads daisy chain from one EMM to another.  Each EMM has a built-in thermocouple.  The EMM essentially insures that the voltage output from the solar module is kept high enough to prevent series degradation.  Without the EMM, a solar module in shade would develop a high resistance and seriously degrade the entire series of solar modules.

Each maximizer communicates with a central Maximizer Management Unit (MMU).  The MMU can be used to control each EMM (to enable or disable one, for instance).  The MMU also collects:

• the performance and temperature of the solar module attached to each EMM,
• solar radiance information from a separate (optional) pyranometer, and
• AC power generation from the inverter (also optional).

The communications between the EMMs and the MMU can be either wired or wireless.  The wired version uses the DC power lines.  This option requires that the MMU be physically connected to the DC power lines at a point after the individual series of solar modules have been 'combined' into a single DC feed.  This is usually just before the individual series DC feeds enter the inverter.

The wireless version of the MMU and EMMs do not require the MMU to be physically connected to the DC feed, so the MMU can be placed anywhere within a reasonable distance of the solar modules, up to 300 feet (90 meters) away.

In order for the MMU to record the AC power generation of the inverter, the MMU will need to be mounted somewhere between the inverter and the power panel.

Availability is an issue.  Supposedly, 60 EMMs and a number of matching MMUs were to be shipped out to AEE Solar in Redway, CA this week.  I need the following:

• 24 EMMs, wired, 72" power leads, MC4 connections for the solar panels
• 1 MMU, wired, with AC metering
• 1 pyranometer (Licor)

Armed with the exact information I needed to place an order, I contacted AEE Solar's CEO, David Katz.  I'd spoken with Mr. Katz several weeks ago and he had assured me that AEE would help meet my need.  Now that I knew the parts that I needed I passed that information on to Mr. Katz as well as to our local AEE Solar distributor, Orrin Farnsworth.  That was last Monday.  On Wednesday I learned that the 'wired' versions were not being shipped yet so I called and left a message that the 'wireless' version would be fine

I haven't heard back yet!

The solar modules cannot be installed until I have the Tigo components, unless I decide to forego the monitoring, which I am loathe to do.  Nevertheless, if I cannot get cooperation from AEE Solar I may be forced to either go to a competitor (DC Power Systems) or live without the Tigo components.