Solar Power II: What you need to know in five parts.

Part Two : Efficiency


Our first installment introduced the various types of solar panel. We will now examine their operating efficiency and costs.

The efficiency of solar panels has a technical limit.

Even in outer space, current solar panels mounted on satellites are achieving just 25 per cent efficiency; and that is operating 100 per cent of the time.  

On earth, that efficiency drops to 20 per cent and the normal cycle of night and day reduces that efficiency to 10 per cent or even less.

A new, lead-based (perovskite) solar panel technology may well be the next generation. Panel manufacture is as simple as applying a liquid to a glass supporting medium. 

Oxford Photovoltaics is the leader in perovskite research. Oxford PV forecasts serious competition for silicon cells, with lower production costs and manufacturing flexibility, if they can achieve generating efficiencies closer to those of monocrystalline silicon.

Solar efficiency  basics

“The Economist” reported: The cost of solar power is not just about the systems that households and businesses install. On cloudy days and at night, they need power from elsewhere: Either from storage of some sort, or from the grid. But who is to pay for it? Backup generation, and the grid infrastructure across which it flows, become increasingly uneconomic as consumers generate more of their own power (and thus pay less to other providers). 

Solar systems rely on the steady absorption of sunlight. In our locale insolation, the amount of sunshine hours  per year, is about 1100. Leaving aside the targeting of the panels, that is the maximum production time for solar panels here. 

Given that there are 8,760 hours in a day, that means for 87% of the time, our power must come from somewhere else, as noted by the Economist.

Sunshine at any spot on the globe is intermittent and often unreliable. Solar panels can deliver roughly 7am to 5pm each day. Solar can help supply the hot afternoon demand for air conditioning, but demand for electricity generally peaks during the dinner period, from about 5:30 pm to 7:00 pm, when production from solar is minimal, approaching zero.

Although solar power is an option almost anywhere on the planet; however, effectiveness falls sharply as distance from the equator increases. Given our high latitude, residents of Southwestern B.C. are at a significant disadvantage; our cloudy weather also has an impact.

Okay, what does it all cost?

A household solar system has four main areas of expense:

Roof structure upgrade;

Solar panels and racking;

Inverter/rectifier and supporting wiring;

Battery system.

If you have a south-facing roof slope that you want to use for your solar installation, you may have to consider beefing up the structure of the roof and its supporting walls to carry the added weight of the panels and their racking; conservatively, figure $3,000 to $5,000.

Next, there are the panels, themselves. From speaking with local suppliers, the installed cost of a solar panel array is about $4 per watt and that the average house would normally see a 4.4 kW system installed. Financing aside, you are looking at an installed capital cost of around $17,000.

If you want to go off-grid, you then have to consider battery storage, which will allow your system to deliver power at night or on cloudy days. 

The trouble is, at the consumer level, each kWh of storage carries a whopping price tag of $600 per kWh. Adding a 25 kWh battery array to a household solar system would tack on $15,000 to the total cost. We should also bear in mind that these batteries will likely need replacement long before a solar panel’s 20-year lifespan is up.

Technology is advancing, though there is a long way to go. Elon Musk’s Tesla Motors Inc. has shaken up the market with its Powerwall battery pack. It looks smart, operates smart but carries a stiff price tag, US$3,500/10 kWh. To kit out a house with 30 kWh of backup power, three Tesla units alone would cost US$10,500. Installation, wiring and inverter/rectifier can easily double the price.

Based on the above, depending whether you want to go completely off the grid or use net metering as a backup. Excluding financing, the real cost of installing a home solar system is somewhere between $20,000 and $37,500; no small investment.

An important side note: Promoters of solar power often declare that the cost of solar is getting lower and lower. The aggressive marketing methods of Chinese exporters have gotten the better of them; earlier in 2015, the Canadian government announced anti-dumping duties ranging up to 289 per cent on solar panels imported from China.

Solar panels deliver, but at a cost

Solar energy works. but what is the cost? Well that depends on the assumptions we make.Depending on where they are made, the solar panels would need to produce emissions-free electricity for years to make up for the greenhouse gases generated by their manufacture. Their components, which include several so-called conflict minerals, are often mined in countries with weak health and safety regulations.

The production of solar panels requires caustic chemicals such as sodium hydroxide and hydrofluoric acid, consumes water, and uses electricity, which emits greenhouse gases. The manufacturing process also creates waste. 

Getting the context right when judging solar power’s impact is vital.

If one ignores the coal burned in China to generate power for glass manufacture, metal smelting and refining, and production of the heavy metal salts that are the critical photovoltaic layer on the solar cell, one can talk about the operating benefits of the cells with some confidence.

However, the fact of the matter is that 70 per cent of the solar cells made in the world are produced in China, where burning coal is the primary source of energy. 

There are other environmental impacts, too; stories of Chinese panel makers dumping silicon tetrachloride on fields near their factories, for example. A backlash is already being felt elsewhere in China. Panel manufacturer Jinko Solar, has faced protests and legal action since one of its plants in Zhejiang province has been accused of dumping toxic waste into a nearby river. 

Next – The Environmental Impact of Solar

Understanding the impact of solar on the environment is vital. This impact is far-reaching and greater than many of us realize. Next week’s segment will give you an overview of this important issue. 

References for Research

“How Much Do Solar Panels Cost” – Energy Informative – The homeowner`s guide to solar panels – Last updated March 23, 2015 by Mathias Aarre Maehlum –

“How Much Does it Cost to Install Solar on an Average US House?” – Solar Power Authority – April 20th, 2012 by Lee Devlin –

“Complete Solar Panel Cost Guide” – Solar Panels Cost Guide

“Everything You Need To Know About Adding Solar Panels At Home” – Forbes – May 17, 2014 by Christine Tusher –

“Meet the battery-powered home” – The Economist –


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