When it comes to some materials, new technology can service both saving in manufacturing cost and enhancing the quality of the end product. Sixtron Advanced Materials, Dorval, Canada, provides a solution with a material that removes a well known hazard, silane gas (SiH4) from PV production.

“Silane gas is dangerous and has caused factory fires and explosions and killed many people,” Bates Marshall, Vice President, Sales & Marketing, says. “But it is still the most common way to get the silicon molecules to the wafers to make the anti reflective coating that goes on top of the solar cell (TOC) before it goes into the module.”

Silane has been used simply because there really hasn’t been a viable alternative. Marshall says that using a very well documented cost of ownership model developed by working with the global engineering firm CH2M Hill based in Colorado, shows that eliminating the silane molecule from the process not only saves cost on the molecule material side but also all of the special handling and safety measures required to do this.

The model basically says that for every dollar you spend on silane gas, you spend another US$2-3 on the infrastructure and handling to safely deliver and use the gas. The total cost of ownership of silane is therefore typically three to five times the amount of the actual material price.

The replacement for silane developed by Sixtron, is a non-toxic, non-explosive, solid source material, which can be shipped by air. “We take this solid material and generate a gas onsite. So instead of having to deal with these compressed cylinders of explosive gas, you can have this small gas generation system which is called a SunBox, to deliver this gas as needed on demand,” Marshall says.

The input to the SunBox is a cartridge of solid, environmentally stable, safe-to-handle polymer. Operators are no longer exposed to danger when performing cylinder changes with pressurized pyrophoric silane. The deposition tools and wafer handling remains the same for the Sixtron solutions.

The current state of the art for coating solar cells is silicon nitrite, which is created by combining silane gas and ammonia in a deposition chamber. The film created from the new solution is silicon carbon nitrite. According to Marshall, it can be used to effectively electrically passivate the solar cell, has good optical characteristics and provides a very good polymeric coating.

Sixtron just announced a major solar customer will be using their new technology in Asia.

“What makes customers willing to use our technology most of all is that it is compatible with the way they make things today. … [It] is easily manufacturable and fits right into any production line. Our process is designed to be transparent upstream and downstream. It is simply a material change,” Marshall says.

Bringing a new edge to old cleaning processes

Everything needs to be cleaned. This is a truism that stems from the basic semiconductor industry and followed the technology as it morphed into solar manufacturing. Singulus Technologies, Kahl am Main, Germany, focuses on increasing efficiency in a key area of both solar crystalline and thin-film production; cleaning wafers, glass back plates and flexible thin-film. Coming out of the optical business and wanting to apply their technology to solar manufacturing, Singulus purchased Stangle semiconductor equipment in 2007.

“We now specialize in wet bench or wet cleaning with equipment for cleaning the raw material or the silicon bloc, the wafers and the final silicon cells. It is always some type of equipment where the material goes through a series of baths and it is cleaned for the next production step,” Bernard Krause, Marketing Communications for Singulus/Stangle says.

Stangle has also brought another major product area to the Singulus partnership; copper indium gallium selenide (CIGS) processing. “[We looked] for a partnership where we could develop a new anti-reflective coating machine for the anti-reflective and passivation layer,” Krause says.

Rather than compete with the large process equipment on the market, the concept was to fill a needed gap with high quality and affordable equipment with a smaller machine. It does the coating process in a single solar cell mode, and “it fits on a table and it the cell goes through the three processes chambers and comes out again and goes on to the next step,” Krause says

The first anti-reflective machine is set for delivery, and more products are coming up. Products are made in partnership with customers based on their needs, Krause says.

An inverter solution for rooftop solar

Solar inverters are key to enabling solar panel end installations, crystalline and thin-film. Inverters take the DC electricity produced by solar panels and invert it to AC at an appropriate voltage for the location and integrates with the power grid.

To achieve high efficiency with all common inverter technology, it requires high input voltages. However, solar PV panels are inherently low voltage devices. So to get the maximum efficiency of the inverters, installers connect solar panels in series. If the input requirement for the inverter is 500 V and the crystalline panels are 50 V each, 10 solar panels are connected in series so the total combination generates the required 500 V output.

The problem, however, with this set up is that if one of the solar panels fails to produce those 50 V for whatever reason – shade hitting it at a certain part of the day, debris building up on part of it, or just a fault in the solar panel itself – it drags down the power of all the panels to its level.

Sustainable Energy Technologies, Calgary, Canada, has not only developed a more effective version of inverter, but also taken the added step of creating a whole new and highly effective method of routing an entire panel layout for higher efficiency and easier installation.

“We have developed a new design of inverter that will increase the yield from all photovoltaic systems,” Gregory H. Nelson, Executive Vice President, COO says. “Our Paralex Energy Technology is a unique low voltage, high yield commercial rooftop solar power system. It offers a ground breaking approach to commercial PV systems that increases total system output while simplifying design and lowering costs.”

These new power solar inverters do not rely on series architecture and instead enable “massively parallel” systems. Paralex combines Sustainable Energy’s Sunergy low voltage inverter with solar thin-film PV or crystalline modules connected in parallel. The company claims that this optimizes the power from each solar module, reducing the impact of shading, soiling, and other real world factors, without increasing installation and maintenance costs by adding electronics to each module. Using a parallel setup for the panels, if one goes out, the others stay at full power – like a modern string of Christmas tree lights.

Aside from the power maintenance aspect, this allows much more flexibility in solar panel placement. It is easier to accommodate rooftop obstacles such as air conditioner units, chimneys, etc.

“Our systems work best with thin-film panels because the output voltage matches our input voltage. Our technology works with crystalline as well, but crystalline panels are lower voltage. They are down into the 25-40 V range so most typically we would require two in each series. Our inverter voltage requirements are 50-150 V as compared to conventional inverters that require 300 V, 600 V or higher,” Nelson says.

Nelson claims that the Paralex system is the lowest cost system available per kilowatt hours produced. In terms of installation, it does not require a string calculation and offers very flexible layout design. Because the solar inverter is low voltage, the components that go into the system are much lower cost than the components needed for high voltage inverters – which also have a higher manufacturing cost attached to the whole assembly.

More power from large installations

Taking power from the rooftop to the solar part or utility installation is where everyone hopes this technology is heading. Skyline Solar, Mountain View, California, says it can enable these large industrial and utility structures with a system that it claims will greatly increase the usable power generated by the panels.

As a baseline, most solar engineers are familiar with solar plants using flat track solar panels or modules, also called high gain solar as it gains more energy out of the same set of materials.

“What we are doing is the next natural step along those lines. We say if you are going to track the sun, along those lines, you might as well do it in the most cost effective way possible by using components that gather even more energy than they could if they were just put under a flat plate, plain vanilla system,” Tim Keating, Vice President of Marketing says.

To do this Skyline wraps some mirrors around a fixture that collect sunlight from a large area and direct it onto a flat plate panel so it can generate more energy. “Our system will reduce the amount of solar panels needed, reduce the needed amount of costly silicon, by 90% when compared to a standard flat plate system,” Keating says.

Taking the “reuse and recycle” slogan beyond the use of the solar system itself, Skyline has also partnered with the struggling automotive manufactures to put plants and workers laying fallow back to work.

“The way we design the systems is that the photovoltaic or solar panel is completely separate and manufactured in a standard module line. So we are really reusing that factory capacity,” Keating says. “Then the system which is a large metallic structure is manufactured in an automotive plant.”

“Basically, this leverages this incredible industrial capability that’s gone into all types of metal stamping and forming and attachment and retooling those productions lines so that instead of building the chassis for a vehicle, they are building the body of our PV system. That is an effective use of our industrial plant system. It is a win-win all the way around,” he adds.

Keating says that Skyline is focused on the design set that integrates all of those materials into a working system. One PVA system was installed earlier in the year and another, larger in size, is scheduled for 2010. This one will reflect the design that will be going into volume production for utilities.

“We are just building off of that theme. The pioneers in this area include some domestic and some European companies that have developed tracking and other systems for High Gain. We view these companies not so much as competitors but as collaborators that will help take solar to the next level,” Keating says.

“Right now in the USA we are fortunate to have the Federal tax credit program for the development of all things solar. As an industry we are all driving cost down so when those incentives go away, our industry will be ready to stand on its own and compete on a level playing field with all other conventional power sources – or even undercut them.”

Wrap up

From the front end to the back end, solar PV innovations are continually being announced. Not all will make it past the R&D stage, but many will and every new technology, material or product that makes the grade will bring the world closer to cost effective solar power.