Thin film vs. monocrystalline panels in grid connect systems

Quite often we’re asked about the advantages of monocrystalline panels over their amorphous thin film counterparts; particularly in home solar power grid connect systems. 

In all our grid connect packages, we only use monocrystalline panels (except in very specific circumstances) for the following reasons:

Less roof space required

Monocrystalline solar panels need far less surface/roof area – and roof space is very valuable real estate when it comes to solar energy related electricity production. You may have just enough roof space to deck it out in thin film panels now; but what about later if you wish to upgrade? We’ve seen instances where home owners have had to rip up all their thin film panels and sell those at a loss in order to boost the size of their solar power system.

In the future, solar energy may also have a huge role in personal transport.  For example, Honda is working on a hydrogen car which will be powered by the sun . In this case a 4-5KW solar power system will create the energy to power a small pump station on the side of the house, creating hydrogen from water during the day which will then be available as fuel for the car. 

With the world rapidly moving towards renewable energy sources and with developments such as Honda’s, we envision a time in the not-too-distant future where the type of solar array used; specifically the ability to scale up, will also factor into house price values.

Don’t underestimate the value of your north facing roof area – monocrystalline solar panels are the best choice, even just on that point alone. 

Ease of installation

Some amorphous thin film panels actually need more mounting rails and take longer to install; adding to the overall cost of the system

Embodied energy

While thin film offers a lower level of embedded energy per panel, the fact that more panels are needed somewhat negates this aspect, especially given the extra mounting rails sometimes needed. Embodied energy refers to the amount of energy required to manufacture and supply a product.

Other environmental concerns

Some thin film solar products uses cadmium telluride (CdTe). Cadmium is a heavy metal that accumulates in plant and animal tissues. Cadmium is a ‘probable carcinogen’ in humans and animals. While cadmium telluride doesn’t pose a threat while the panel is in service, disposal of this toxic waste when the product reaches the end of its life comes at large cost and suitable facilities are not present in Australia currently

General performance

We’ve noticed that some companies use reports and impressive graphs on efficiency to show amorphous thin film as being superior. In most cases we’ve seen, the data is taken from the late 1990’s – it’s over 8 years old! Like any technology, solar power has rapidly evolved, and that includes the performance of monocrystalline panels.

In most conditions in Australia, we strongly recommend monocrystalline panels; the only exceptions being far North Queensland and the Northern Territory where amorphous thin film may have some performance advantages during the hottest times of the year and given the amount of solar radiation in those areas (a separate issue to heat.).

Durability

Thin film is still relatively new technology whereas monocrystalline panels have been around for decades. Some monocrystalline panel installations in the 1970’s are still cranking out power today. Monocrystalline has even withstood the rigours of space travel! Amorphous thin film is yet to prove itself in harsh conditions over a long period of time.

Flate plate vs. tempered glass

In many grid connect packages where thin film is utilized, the panels are covered with plate glass – this is incredibly inferior to tempered glass, both from a safety and durability aspect. The type of glass used in a panel is so important – it just doesn’t pay to cut costs by cutting corners on material quality. We’ve published a full article just on this topic – plate vs tempered glass.

Exaggerated claims of shading tolerance

The simple fact of the matter is, no panel is shade tolerant to any great degree and it just doesn’t make sense to install an expensive solar power system in an area that experiences a great deal of shade as the system’s performance will be extremely low.

Comparing apples to apples in grid connect

In a addition to the above points, if you’re looking to buy a solar power grid connect system, ensure you compare similar systems in terms of price – what you are getting for your money. The difference between a 1kw system and a 1.3kw system may not sound like much, but there’s a huge difference in power output; approximately 33%.

Adding to your system in the future

As mentioned, our 175W and 180W monocrystalline panels are some of the best in the solar industry – proven, long lasting, produced in high quantities and will still available for years to come. If in the future you wish to increase your system or need to replace a panel for whatever reason, there will be no shortage in obtaining these products. Many manufacturers actually produce very similar panels in terms of dimensions, so that you are not tied to one particular manufacturer, but actually have a choice(see table below). 

In the case of thin film there is no such assurance as these panels are produced in much lower quantities by a smaller number of manufacturers. You might find that you are stuck with old technology that cannot be easily upgraded

Mono-crystalline solar module comparisons (showing similarities of panels)

So why do we sell thin film panels?

Energy Matters does stock thin film solar panels, all good quality brands. As mentioned, we recommend amorphous thin film for North Queensland and for the Northern Territory. Flexible thin film panels are also extremely well suited to curved structures where flat panel mounting isn’t viable. Thin film is also desirable for some off grid and mobile applications as they are lightweight. Finally, we also sell them because our customers demand them, however we do point out the advantages of monocrystalline when people enquire.

There’s a great deal of competition among suppliers of grid connect systems now given the generous government solar power rebates on offer and the decreasing price of solar technology. It’s very important that consumers shop around and check the way systems are promoted against the actual facts behind any particular type of component before making a purchase decision. Don’t be afraid to ask questions – after all, it’s a substantial investment and a decision you’ll be living with for a very long time! 

Confused about grid connect solar power? Contact one of our friendly experts for free, no-obligation advice tailored to your specific needs on 1300 727 151 or via email

Types of solar collectors for electric generation

Parabolic troughs, dishes and towers described in this section are used almost exclusively in solar power generating stations or for research purposes. The conversion efficiency of a solar collector is expressed as eta0 or η0.

[edit] Parabolic trough

Parabolic trough

This type of collector is generally used in solar power plants. A trough-shaped parabolic reflector is used to concentrate sunlight on an insulated tube (Dewar tube) or heat pipe, placed at the focal point, containing coolant which transfers heat from the collectors to the boilers in the power station.

[edit] Parabolic dish

Solar Parabolic dish

It is the most powerful type of collector which concentrates sunlight at a single, focal point, via one or more parabolic dishes — arranged in a similar fashion to a reflecting telescope focuses starlight, or a dish antenna focuses radio waves. This geometry may be used in solar furnaces and solar power plants.

There are two key phenomena to understand in order to comprehend the design of a parabolic dish. One is that the shape of a parabola is defined such that incoming rays which are parallel to the dish’s axis will be reflected toward the focus, no matter where on the dish they arrive. The second key is that the light rays from the sun arriving at the earth’s surface are almost completely parallel. So if dish can be aligned with its axis pointing at the sun, almost all of the incoming radiation will be reflected towards the focal point of the dish — most losses are due to imperfections in the parabolic shape and imperfect reflection.

Losses due to atmosphere between the dish and its focal point are minimal, as the dish is generally designed specifically to be small enough that this factor is insignificant on a clear, sunny day. Compare this though with some other designs, and you will see that this could be an important factor, and if the local weather is hazy, or foggy, it may reduce the efficiency of a parabolic dish significantly.

In some power plant designs, a stirling engine coupled to a dynamo, is placed at the focus of the dish, which absorbs the heat of the incident solar radiation, and converts it into electricity. See Knowing Parabolic Concentrators and Concentrating Solar power overview

[edit] Power tower

Power Tower

A power tower is a large tower surrounded by small rotating (tracking) mirrors called heliostats. These mirrors align themselves and focus sunlight on the receiver at the top of tower, collected heat is transferred to a power station below.

[edit] Solar pyramids

Another design is a pyramid shaped structure, which works by drawing in air, heating it with solar energy and moving it through turbines to generate electricity. Solar pyramids have been built in places like Australia. Currently India is building such pyramids.^[4]

[edit] Advantages

• Very high temperatures reached. High temperatures are suitable for electricity generation using conventional methods like steam turbine or some direct high temperature chemical reaction.^{[citation needed]}
  
• Good efficiency. By concentrating sunlight current systems can get better efficiency than simple solar cells.
  
• A larger area can be covered by using relatively inexpensive mirrors rather than using expensive solar cells.
  
• Concentrated light can be redirected to a suitable location via optical fiber cable. For example illuminating buildings, like here (Hybrid Solar Lighting).

[edit] Disadvantages

• Concentrating systems require sun tracking to maintain Sunlight focus at the collector.
  
• Inability to provide power in diffused light conditions. Solar Cells are able to provide some output even if the sky becomes a little bit cloudy, but power output from concentrating systems drop drastically in cloudy conditions as diffused light cannot be concentrated passively.

BNSF Railway and Vehicle Projects Demonstrate Experimental Hydrogen Fuelcell Hybrid Switch Locomotive

30 June 2009

Rear view of the fuelcell hybrid switch locomotive. The dual Ballard fuel cell stacks are to the left (i.e., rear) of the switcher. Source: Vehicle Projects. Click to enlarge.

BNSF Railway and Vehicle Projects Inc. of Denver/Golden, Colo., a developer of large fuelcell vehicles such as mine loaders and mine locomotives, unveiled an operational hydrogen fuelcell hybrid switch locomotive at BNSF’s Topeka System Maintenance Terminal. (Earlier post.)

Following its introduction, the locomotive is heading to the Transportation Test Center in Pueblo, Colo., for additional testing. Late this summer or early fall, depending on the outcome of the testing, the locomotive will go into service in the Los Angeles Basin, where it will face the test of actual service in the railroad environment.

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BNSF operates through several locations that are in non-attainment areas for air quality as designated by the Environmental Protection Agency. We are investigating and experimenting with this hydrogen fuelcell technology for its potential niche application in areas with air quality concerns.

—Mark Stehly, assistant vice president, Technical Research, Development and Environmental

 

Arnold Miller, president, Vehicle Projects, suggests that the fuelcell locomotive is the least-cost solution for such areas when the social costs of diesel-electrics and the infrastructure costs of catenary-electrics are considered.

The fuelcell powertrain was developed by Vehicle Projects with the support of BNSF, the US Department of Defense and a collaboration of industrial partners. The switcher is being also designed to be able to serve as a mobile backup power source (i.e., “locomotive-to-grid”) for military bases and civilian disaster relief efforts.

Expanded view of fuelcell hybrid switcher. Source: Vehicle Projects. Click to enlarge.

The locomotive features a 240 kW (320 hp) fuelcell prime mover (based on the stacks used in Daimler Citaro hydrogen fuel cell buses. It stores 70 kg hydrogen at 350 bar (5,100 psi) at roofline. A lead-acid traction battery allows transients above 1 MW. The locomotive has 9,000 kg of extra ballast to bring it to 127 tonnes.

The vehicle platform was based on the Green Goat diesel-battery hybrid switcher.

Resources

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  The BNSF FuelCell-Hybrid Switch Locomotive for the Los Angeles Basin (March 2009)

June 30, 2009 in Fuel Cells, Hydrogen, Rail | Permalink | Comments (7) | TrackBack (0)

Comments

There is little doubt that the energy potential of tides is huge. The largest power plant is the La Rance station in France which generates a whopping 240 megawatts (MW)of power. The idea of constructing a power plant on the La Rance dates to Gerard Boisnoer in 1921. The site was attractive because there is a large average range between low and high levels (8 metres, with a maximum equinoctial range of 13.5 metres).

In spite of the high cost of the La Rance project, the plant’s costs have now been recovered, and electricity production costs are lower than for nuclear power generation. (18 Euro cents per kWh, versus 25 per kWh for nuclear). However, the barrage has caused progressive silting of the Rance ecosystem. Sand-eels and Plaice have disappeared, though Sea bass and cuttlefish have returned to the river. There are only two other plants operating worldwide, one being the 20MW Annapolis station in Nova Scotia, and a small 0.5MW plant in Russia.

Tidal power schemes do not produce energy 24 hours a day. A conventional design, in any mode of operation, would produce power for 6 to 12 hours in every 24 and will not produce power at other times. As the tidal cycle is based on the period of rotation of the Moon (24.8 hours) and the demand for electricity is based on the period of rotation of the earth (24 hours), the energy production cycle will not always be in phase with the demand cycle. This causes problems for the electric power transmission grid, as capacity with short starting and stopping times (such as hydropower or gas fired power plants) will have to be available to alternate power production with these power schemes.

The less intrusive plants utilising kinetic energy from current flow rather than potential energy of barrage dams would appear to be more environmentally friendly and sustainable in the long term.