There are solar shading tools available to mitigate the effects of shading on an array. Essentially, they are additional bypass diodes wired into the back of the solar panel. With the addition of these bypass diodes, the shaded portion of the panel is "bypassed." This bypass feature helps to reduce the loss in output caused by shading a series wired panel. These are often called solar "optimizers" or solar "maximizers."

In the above photo, there are power lines that shade the array at least an hour or so each day.  When we installed the system without the shade mitigation tools the system voltage was 280 volts.  After installing the maximizers the output was 300 volts! A gain of 7%! That is a huge gain over the lifetime a system.  There are multiple manufacturers who offer these shade mitigation tools.  With the addition of the mitigation tools, we can now add panels where they might have not been before, as in the shadow of a chimney, tree or vent pipe.

There was a unique opportunity at the recent AEE dealer show for attending the panel discussion of shade mitigation, with the represenatives from these companies. 

Here are the notes from the panel discussion (or smackdown...) :

or, as David Katz says, “Things that go on the back of the panels.”

Enphase,Tigo, Xandex, Solar Edge.

Shade mitigation or Individual module MPPT is the new Hottest topic on solar.

“Bringing intelligence to the module”

More companies lining up with similar technologies.

Shaded panels are like batteries in flashlight. One bad battery in flashlight lower overall power of all batteries.

A 'little bit of shade' is what blocks out most power. 10% shade usually equals 80-90% reduction or

½% shade drops production 5% unless all of a cell is covered then that row goes out. Only three rows in a module.

Some of these products address problems in shade mitigation in panels that have been installed in shade. Others to get most power out of all modules in the string.

Ohms Law I x V= W

Some systems have resolved safety issues (solar edge). High voltage on roof for fire (Tigo Jeff).

Tigo- As soon as a module is degrading power (more loss) to the string higher than it's contributing, it will trigger the bypass diode.

Tigo MSRP $56

Tigo Jeff says- Vmp (in constant temp) maximum power volts will be the same no matter how much radiance is available to the system. If panels are all operating and one panel is shaded, inverter will move max power point and move max power point down for existing panels. Reduced output of other strings as well. Real power loss.

Tigo Jeff- “I think it's tremendous that we have enough people in the market to have a market panel. Migration of talent into PV. 2007. PV is a “network of individual power sources”. Not just addressing shade. Duration for soil, thermals, clouds, can not design out 'mismatch' never less that 12% mismatch during the daytime. Bringing 'intelligence to modules for debug and optimization and information. Disconnect is important for firefighters and installers. “Not an inverter company” we work with their products. Efficiency most important. No heat dissipation from product. Smallest power loss from panel. Software company. Give 'intimate details' of system for life of system. Don't transform DC to DC on each module. Tigo communicates from each maximizer on two-three second cycle: input values, string parameters and calculates where each module needs to be. (vmp of each module). Fixed output of string is calculate by strongest panel in the string.

?'s DC product goes on every panel on system?

Answer: Yes. 5% to be gained during peak operating hours. Drive efficiency of each panel. Plan to drive cost of this technology down.

?'s: Do you need them on all of the strings?

A: No.

Xandex Tim- 30 years offering 20 year warranty. Only US made product from panel. From semiconductor industry. Tested quality.

Been making Sunmizer for three years. Can be deployed selectively, only to panels in string that are shadowed. Simple approach. Minimal components. Can use just one of them, if needed, on system. Efficiency similar to Tigo. Can't use with Evergreen currently as it will NOT accept more than 9 Imax Isc

Product has been tested in field over a year and no problem. Both roof and ground mount.

?'s Cost

A $313 list

? efficiency

A: 98.5% lowest. Average is 99%

Does not address mismatch. To much trade off in power loss to put electronics on each panel.

? Does it have to be grounded?

A: Yes. Easy to run ground wire through or weeb.

SolarEdge- Company 2006 founded. Based in Israel. GE invested in company. Competition? Is it fossil fuel? Not mitigation company but mitigation company. Founded by power electronic engineers. Want to improve over all picture. Aim to make difference across board. Simplicity through system design. Biggest energy loss is over and under voltage of systems. Our system designed to simplify layout of system; no limitation in string size, overcoming issues of panel mismatch, soiling, dust, roof utilization and shading. Can use different size and makes of panels on same string. Can mix and match size, types of strings. Effective maintenance and recovery. Must be on every module. Planning to have them embedded on modules. Inverter with no MPPT function. Fixed voltage in the string. Module level monitoring. Anti-theft system.

?: If you have a long string. It just can't be in a parallel with short string.

A: Yes, you can have short and long strings.. Inverter is operating at fixed voltage. Allows for mix-match and parallel short and long strings connected to inverter. Accumulated voltage of panels is the fixed voltage.

? $ for $ is it more expensive?

A: Plan is to maximize value with minimizing cost. 12 year warranty on inverter. Same price as SMA inverter. Have solution for thin film issues as well.

DC to DC converter.

? Does your system have separate converter box (98% efficient)?

A: No From inverter to router.

?? pay 1% power for efficiency

A; Inverter operating at peak efficiency (97.7) at all time, but 1% loss.

Can detect DC arcs and communicate and shut down system.

?: If I use your system am I married to your inverter and the rest of your systems?

A: For now, yes. Not for retrofit now. Not the best use of this technology.

Enphase Jeff. Started in 2006. Engineer started company to make improvements in technology, monitoring. Beta tests for three years. 200,000 units shipped out.

Invert PC power from single module. Advantages over sting. Can design from one module to multiple modules until you run out of space. No DC wiring leaving the array. Components in system are single micro inverter from each panel. Internet gateway gets data from each panel and. Maximum pp (MPPT) conversion right at each module. Monitoring-website of the array available from internet anywhere. AC bus is parallel bus. Daisy chain. Distance is a limitation as it is lower voltage. 15 amp on single branch circuit.

? Limitation on distance because of limited voltage?

A: Yes. Concerned about voltage drop. Use larger wire to go further.

Advantages to converting to AC right at array.

? Planning to make something that will work with larger than 230 watt panel.

A: Yes. Looking at products to come out with. Higher wattage and higher voltage (think thin film) in the future.

? Combining technologies with modules?

A: Replace junction box etc. Hope to have running system with real partner.

Tigo: We all want these units on back of every unit made. This year module guys have similar modules and are looking for technologies that will make their modules 'stand out' from other modules. This was not so last year. Next year there will be modules with 'smart technologies'

? Enphase had panel last year. Was it a mock-up.

A: Katz said, “It was an innovative installer producing a product.”

? Katz:string sizing must still be consistent with Tigo?

A: follow inverters suggestions. Can you get it past inspectors? Do they look at output of panels or maximizers? Most look at output of panels. Be careful about longer string sizes when it comes to passing inspection.

? Katz: Your power box changes voltage of string for short period of time. Does the power point tracking of a system change during those times?

A: IV curve is multi-peaked. We smooth that out into smooth power curve- loss Is nominal.

? Made in USA

only the Xandex solar optimizer is made in the USA.

? tigo: 5 to 6% incremental output during day?

A: put censors on modules for six months to look at string performance on each module. Found constant pattern than showed voltage variance from 12 to 15%. (Dust, clouds etc.) Increased output only happens when there is mismatch. Brings voltages back to peak operating point. Out of 15% loss, we can get 6% of that back. We are talking about peak production hours. $

? Enphase. System loss from inverter to each module

Only loss from inversion. No line loss. Conversion efficiency. Longer AC wire than with string.

? Tigo Mounting and grounding?

A: plastic box? We don't use plastic box. Unit snaps to corner. Our device is made from polycarbonate.

? Tigo-Mismatch caused from degrading silicone.

A: Degradation will very from same modules in the same string. This is because of the nature of silicon.

Tigo Jeff says he did his own study and says he found a 10% degradation over 10 years

.Other dude says 1% per year and thin film 2-3% per year. Difference between mono and poly modules about the same.

Warranty. 25 years? Tigo says “yes” same as panel.

? What competitor would you buy from.

Xandex says 'every installation is different.

SolarEdge would buy Enphase. System based solution

? Enphase Jeff would buy SolarEdge

Tigo weaseled out of answering.

? what is the ideal thing your product does best?

Tigo- large scale unshaded. Peak performance in large, unshaded systems.

Enphase- smaller systems with multiple roof angles and challenging small sites.

SolarEdge- Commercial rooftops, residential rooftops. Small portions of large fields.

Xandex- You can use just  where the shading occurs, made in USA - build quality.

? Long term maintenance. Do you see using your systems as optimizing systems by trading out degraded panels?

A: Having instant insight into what is going wrong makes most $. sense.