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Detailed reviews and information of the best solar panels, inverters and batteries. Plus hybrid and off-grid solar system reviews and information articles on how solar and battery systems work.

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Reviews and information on the best Solar panels, inverters and batteries from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.

Top 7 solar myths busted

Jason Svarc

Solar Array Kinglake s.jpg

For one reason or another there’s a vast amount of misinformation on online about disadvantages or problems with solar panels. Also, some odd claims about solar panels being toxic, unreliable or not helping reduce emissions. Much of this information originated in the early 2000’s when rooftop solar was a relatively new technology and very expensive. During this period a few of these claims were even true. However, solar technology has advanced rapidly over the last two decades, the cost of solar panels has plummeted, efficiency has increased dramatically, and reliability has improved. With the increasing number of debates about the pros and cons of solar, it’s time to clear up some of these common misleading myths.

Top solar panels myths

  1. Solar panel will not pay for themselves

  2. Solar panels increase the cost of electricity for those without solar

  3. Solar panels don’t work in high temperatures

  4. Solar panels don’t work when it’s cloudy

  5. Solar panels will work during a blackout

  6. Solar panels use more energy to manufacture than they produce

  7. Solar panels are toxic and can’t be recycled

 

Myth 1. Solar panels will not pay for themselves

If you ask anyone who has solar panels installed, chances are they will have noticed a large reduction in their electricity bill. Not surprisingly, those who do notice big savings are also generally more aware of how much energy they use and when they use it. These energy conscious individuals will often be a little clever and use energy intensive appliances during the day. Things like dishwashers, washing machines, pool pumps and hot water systems can be setup on timers to maximise the ‘self-use’ of your solar energy. Pre-heating or cooling your home can also be an effective way of increasing self-use rather the feeding excess solar back into the grid for very little return.

The payback period for solar on most homes is 4-6 years. For businesses which operate during the day the payback can be as fast as 3 years. Not bad, when the life of a solar panel is generally 20+ years and most manufacturers offer a 12 - 25 year warranty.

Poorly positioned solar panels

Some people who install solar may not notice much of a reduction in electricity costs. This is generally due to most of their electricity consumption occuring during the evening. Unfortunately, poor performance is also often due to badly designed systems with excessive shading from trees or rooftop mounted obstacles. Most solar systems use string solar inverters which are connected to a string of solar panels - panels linked together in a row. Partial shading of one or more panels in a string results in a power reduction in the whole string.

Luckily, partial shading issues (as shown below) can be overcome by using DC power optimisers or micro-inverters which enable each panel to operate independently. These devices reduce the effects of partial shading and significantly improve the performance of the system.

An example of shading on a string of solar panels from a rooftop air-conditioner. Without panel  optimisers  the partially shaded solar panels will dramatically reduce the performance of the whole system.

An example of shading on a string of solar panels from a rooftop air-conditioner. Without panel optimisers the partially shaded solar panels will dramatically reduce the performance of the whole system.

Some larger households may also use a lot of electricity (30 to 50kWh per day) for heating, pools or hot water. In this situation a typical 5-6kW solar array may just be far too small. Larger homes with high consumption will need a larger size solar system, plus owners should try to install more efficient appliances.

The reasons above also highlight why you should purchase solar from a reputable solar company and not a door knocking salesman who will promise you “no more bills” just to make a quick sale.


Myth 2. Solar panels increase the cost of electricity for those without solar

This is a common misinterpretation and is often used to downplay the many benefits of getting solar. In Australia there are now over 2.2 million solar installations due to this simple fact - for most homes and businesses, solar is the only way they can reduce electricity costs. Unfortunately, not everyone can install rooftop solar and this has led to some suggestions that others will have to pay more. In reality the opposite is true…

Total electricity generation data from OpenNEM - Rooftop solar accounts for close of 20% on hot days.

Solar energy from the millions of homes and businesses is reducing the peak demand on the electricity network which is effectively taking the ‘stress’ off the national grid. As the population and cities grow, the greater demand for electricity would usually result in the need for larger transmission lines, upgrades and new thermal generators. These huge infrastructure costs would then be passed onto all electricity consumers.

Fortunately, there is so much excess solar energy coming from rooftop solar in cities (especially during hot days when demand it very high) that it is reducing the need for large transmission and network expansion to cities. However, in some locations where the concentration of homes with solar is very high, the excess solar energy (on days with low demand) can rise the grid voltage which can in turn shutdown solar inverters. This is where increasing self-use through heating hot water or installing a battery system can be very beneficial.

Excess solar is also reducing the need for expensive gas power stations, known as gas peaking plants. This in turn is reducing wholesale electricity price in several states. The reduction in ‘peak demand’ is particularly important and helpful during heatwaves when older thermal coal and gas generators often struggle to meet the high demand.


Myth 3. Solar panels don’t work in high temperatures

Surprisingly this is a rather common misconception that is completely false. Solar panel efficiency is slightly reduced at elevated temperatures but they never stop working at a specific temperature. A solar panel’s power rating, measured in Watts (W), is measured in a lab at 25°C. However, in the real world when a solar panel is exposed to sunshine, the temperature of the solar cells will rise to about 20°C above the ambient air temperature. So on a 25°C deg day, the cells could be close to 45°C (depending on the wind and orientation of the panel). This is turn will reduce the cell efficiency, which usually equates to a 8% to 10% reduction in power output. However, on a very hot day above 40°C a solar panel can reduce output by 12% - 18%.

Thermal Infrared image solar panel temperature 2.jpg

The amount of power loss at high temperature is determined by ‘power temperature co-efficient’. This is typically 0.4% per °C above 25°C. Panels with monocrystalline solar cells are slightly better than polycrystalline cells, but then best performing panels use the more advanced IBC and HCT cells. Read more about solar panel efficiency.

The opposite effect can occur when the air temperature is below 25 degrees, or if there is a very cold wind blowing across the panels. The cooling effect of low air-temperature and wind actually increases the performance of solar panels.


Myth 4. Solar panels don’t work when it’s cloudy

Like the clouds in question this one is a little grey. Solar panels will very rarely stop generating during cloudy weather and the reason is quite simple - clouds don’t completely block sunlight, otherwise it would be completely dark outside during bad weather.

Solar cloudy weather problem.jpg

The amount of solar energy generated during cloudy weather is reduced due to solar radiation being absorbed or reflected by the clouds. How much radiation passes through the clouds depends on the type of cloud and its density or thickness. Surprisingly, some high level thin cloud layers can scatter the sunlight which results in a slight increase in generation, especially during early morning and late afternoon.

During ‘normal’ cloudy weather the amount of solar generation is typically reduced by 60 to 80%, depending on the time of day and time of year. Summer is obviously much better than winter. However, during a thunderstorm or when clouds are very dark, the amount of solar radiation can be reduced to 5 or 10% compared to full sunshine, so the solar generation will be reduced accordingly.

In summary solar generation can be significantly reduced during cloudy weather but it varies depending on the type of cloud and time of day.


Myth 5. Solar panels will work during a blackout

Due to the strict safety requirements common grid-connected solar systems are required to shutdown during a grid outage or blackout. Blackouts often occur during severe storms when trees fall across power lines. To protect the emergency workers and service personnel fixing the damaged lines, all solar inverters must be automatically deactivated within 2 seconds of a blackout or a major grid voltage fluctuation being detected.

However, most ‘hybrid’ systems with battery storage are able to isolate from the grid during a blackout (called islanding) and provide some level of backup power. Generally, the amount of backup power is limited to lights and basic appliances, but several more advanced systems using multi-mode inverters are able to offer full backup power to most household appliances.


Myth 6. Solar panels use more energy to manufacture than they produce

Solar panels do not produce any emissions while in use but they are made of different materials including glass, aluminium, silicon and some plastics, which all require different levels of resources and energy. The energy used to extract, refine, transport and manufacture a product is known as the ‘embodied energy’. A typical solar panel will generate enough energy to repay the embodied energy within 3 to 4 years, however as panel efficiency increases this is expected to reduce to less than 2 years within the next decade.

Close up of common silicon crystalline solar cells made mostly from high purity silica sand.

Close up of common silicon crystalline solar cells made mostly from high purity silica sand.

The energy payback time of solar panels is supported by multiple studies and life-cycle analysis (see references below). However, many detailed studies are now very out-dated as solar cell efficiency has increased dramatically over the last few years. Due to increased efficiency and improved manufacturing methods, payback time for many modern systems could already be less than 2 years. Considering a well made solar panel will last 20-30 years, it will easily repay the embodied energy multiple times over and offset thousands of tonnes of emissions.


Myth 7. Solar panels are toxic and can’t be recycled

The claims of toxic solar panels come from the obsolete thin-film or ‘amorphous’ solar panels. These older generation, less efficient panels were sold up until around 2010, but quickly became obsolete due to the huge advancements in silicon crystalline solar cells which were also much more efficient.

While the old thin-film solar panels did contain trace amounts of cadmium, unless the panels are broken up into fragments the very small amount of cadmium is contained and cannot leach out. It’s important to note that there are many toxic elements used in common consumer electronic devices, mobile phones, TV’s and computers which is why electronic or E-waste is a large global problem.

Common solar panel construction using typical silicon crystalline solar cells made using silica sand.

Common solar panel construction using typical silicon crystalline solar cells made using silica sand.

Approximately 96% of all solar panels installed globally are made up of silicon crystalline PV cells encased in a polymer material and protected by a glass front and aluminium frame. There are no toxic materials except for a trace amount of lead used in the solder. However, even the use of solder is being phased out with the new busbar compression joining techniques and conductive paste materials being used.

Recycling

Most solar panels installed over the last 20 years are still in use so there is a relatively small amount of solar waste. However, over the next 10-20 years many thousands of systems will reach the end of life (EOF) and there is expected to be a large increase in the volume of solar related waste which will need to be recycled.

Solar panel recycling is an emerging industry but due to the easily recycled materials such as the aluminium frames and mounting systems there are many recycling facilities being built around the world. Most solar panel manufacturers are pushing to be more sustainable and are now part of the not-for-profit PV Cycle organisation - “PV CYCLE offers members and waste holders better access to take-back and ensure recycling rates above the industry standards.”

  • In Australia there are several companies which will recycle old or damaged solar panels including the Adelaide based ReclaimPV. http://reclaimpv.com/

  • In Europe the French waste management company Veolia has opened the first dedicated solar panel recycling facility in southern France which is able to recover and recycle 95% of the materials.

  • For further reading here is a great article from RENEW about solar panel recycling.


References

Detailed life cycle analysis of solar PV systems

  • http://www.appropedia.org/LCA_of_silicon_PV_panels

  • http://iea-pvps.org/fileadmin/dam/public/report/technical/Future-PV-LCA-IEA-PVPS-Task-12-March-2015.pdf

  • https://www.researchgate.net/publication/264672000_Life_Cycle_Analysis_LCA_of_photovoltaic_panels_A_review

Manufacturing Silicon Wafers

  • https://sinovoltaics.com/solar-basics/solar-cell-production-from-silicon-wafer-to-cell/

  • https://pv-manufacturing.org/silicon-production/cz-monocrystalline-silicon-production/

Wholesale electricity price reduction

  • https://arena.gov.au/projects/peak-demand-reduction-using-solar-storage/

  • https://theconversation.com/wind-and-solar-cut-rather-than-boost-australias-wholesale-electricity-prices-119979