Solar PV: opinions, merits, challenges

I read a lot about solar photovoltaics (PV). Some people believe they will save the world and that, in the future, we'll have electric cars with a solar panel on the roof (let's call them techno-utopians). Others believe that solar is useless. Interestingly, that latter group fall into two main groups (in my experience):

1. fossil-fuel-loving climate-change-deniers, who think that solar will never replace coal/oil/gas
2. devoted environmentalists, who believe that the cost of manufacturing solar PV outweighs its benefits (presumably, they believe that some sort of return to a non-industrial society is therefore required)

I have sympathy for the environmentalists, and can see where they're coming from, but I think they're wrong. I also think the deniers are wrong. I believe that solar PV can replace many uses of fossil fuels, and is starting to do so right now.

Making solar PV

Solar PV panels are reasonably energy-intensive to manufacture. They are a semiconductor and, although they don't require the same level of precision as (say) computer chip fabrication, PV factories still require clean-room manufacture. They also require a large number of obscure material inputs. This is energy-expensive. However,

1. Even with current technology, a solar PV system is thought to be energy positive after as little as a few years (ie. it has produced all the energy in its manufacture). [1] (remember that the system will generally last well over 25 years)
2. There is much research into lower energy cost solar panels. This may reduce the energy and material inputs still further

Solar PV performance

The amount of sunlight falling on the ground represents an absolute maximum to what energy a PV panel can produce. However, given most panels operate at well below 20% conversion efficiency, there's a lot of headroom! In other words, I'm not sure that lack of winter production is quite as bad as it is often made out to be.

PV panels "thermally derate", which means their production decreases when they're hot. On cold days, they work much more efficiently. Thus, if panels are oriented for winter production, cooler temperatures mean that they'll work more efficiently. This increase in efficiency tends to partially offset a lack of winter sun intensity. Of course, a cloudy day is a cloudy day, and production will be lower. Such is the nature of renewables.

What is solar capable of at a domestic level? Evidence

I have a 2 kW system at home, facing due north at about 22deg inclination. I have taken regular meter readings for the last 12 months, and throughout last winter I exported on average 3 kWh/day to the grid (in other words, the panels' average production was greater than this, because some of their power was consumed on site and not exported). I live at latitude 35 deg, in a climate that is often overcast and rainy in winter.

The data I've collected are shown in this article. Note that the winter data look artificially bad because at the time we had an electric storage hot water system that was consuming about 6 kWh/day (now replaced), some of which was produced by our solar PV and hence not exported to the grid.

My feeling is that my family of four could go off-grid with the system we have now. It would not be hard for us to live within our solar PV energy budget as it currently stands. It is possible that we are doing this right now, however winter 2015 will show whether our solar PV production exceeds consumption. Right now, I'm betting it will.

But, solar PV can't power industrial society!

The simple fact is that we do not know if we can run an industrial society on solar PV and wind power -- we've never done it before. I think that, given that an industrial society can be run on 1% (or less) of current power consumption, that it is possible to do this -- though there would be challenges. The question is: do we have the political will to vastly reduce our energy consumption to enable a complete transition to renewable energy?

I think we need to conceptually separate technical and political limitations. I especially think we should not limit political considerations based on incorrect technical opinions (eg. someone saying "we should not invest in solar or a transition to renewables because it is technically infeasible to replace fossil fuels and maintain our society": the latter part of that statement is unproven)

Solar is not a silver-bullet -- there are no silver bullets -- but solar can do a lot. Some people think that anything that is not perfect is useless. That logic is fallacious, in my opinion.

Off-grid versus grid-tied solar PV systems

While I'm at it, I also tire of criticisms of grid-tied solar, as if only off-grid systems have merit. In broad strokes, having a network will almost always represent better resource use than having batteries, because it means that resources can be shared (compare the installation and maintenance energy-costs of batteries versus a grid connection). If a network is available, it is best to use it (even if it is a "network" of two dwellings). By all means add some batteries if you want, as this can help the network function more effectively, but setting up batteries as an off-grid system means one requires a massive excess of storage for the rare occasion that it's needed.

Conclusion

Our current way of life is unsustainable. This means it won't continue. We cannot keep burning fossil fuels. Solar PV offers an alternative energy source that is available right now, that can probably allow us to maintain many/most important aspects of our society. 

It is not certain that we will successfully transition from fossil fuels to renewable energy. Failure to do this means our civilisation will collapse. We need to be installing as much solar capacity as possible, as quickly as possible, and not waiting for some pie-in-the-sky, perfect technology to appear. 

To the greenies who don't believe in solar PV or renewables, I say: fine, don't use them. But don't keep using coal/oil/gas powered electricity -- you know that road is a dead-end.

References

[1] http://www.nrel.gov/docs/fy04osti/35489.pdf

Reducing electricity consumption to affect political change

Many people are concerned about the negative effects that humans are having on the Earth's ecosystems, and with good reason: those systems support us, and without them we would not survive. It is estimated that for every dollar of GDP produced, the natural world contributes .75c -- these are services that nature provides for free and, without which, our quality of life would drop by 75%.

A big cause of human destruction of natural systems is in the provision and delivery of energy. The main culprits are fossil fuels which are starting to alter the world's climate -- a change that, if unchecked, will wreak great destruction on both the natural and human systems that support us. There are now technologies (solar PV and wind turbines) that can produce energy with much  less damage to the environment, and it is imperative that we transition to these as soon as possible. Unfortunately, there are entrenched interests that are heavily committed to fossil fuels and use their influence to slow the adoption of newer, less harmful, methods of energy production.
What is clear is that majority political support for serious action on climate change is currently lacking.

There are huge forces at work here. In the absence of a government with the ability and disposition for serious action, what can an individual do to help this process?

Number one: Use Less

When it comes to reducing one's impact on the systems that support us, there is simply no substitute for using less. Even "green" energy sources have impacts (albeit much more minor). Using less frees money and resources that can be better deployed by helping other, less fortunate, people adapt.

Number two: Avoid electricity or fuel where possible

Electricity is hard to produce, and there are always wastes and damage to the environment -- even when using solar PV or wind turbines. This is because the manufacture, installation and maintenance of these generally result in carbon emissions and other forms of pollution.
Therefore, if a task can be performed without using electricity at all, it is preferable to do so. A great example of this is hot water, which can be heated directly from the sun without need for electricity at all. By doing this, your electricity consumption will be much lower.
Similarly, a solar cooker can cook food without fuel or electricity, using only heat directly from the sun. These are simple and cheap to build.

Number three: buy carbon-emission-free ("green") power, and/or install solar panels

Here is where your large reductions in consumption will help -- because you're now using a lot less power, you will not need many solar panels to offset your electricity consumption (cheaper!).
At my house, we have reduced our power consumption to about 3 kWh/day for a family of four without significant lifestyle sacrifices. I think it can go lower still. We have a 2 kW solar PV system, which produces an average of about 6 - 8 kWh/day (averaged over the year) -- more power than we consume. We do draw power from the grid though, as we do use power at night (when the PV panels aren't producing), which is why we also buy carbon-emission-free power. By doing this, we ensure that we're not directly supporting the use of coal for electricity generation and because our power consumption is so low, the additional cost is very small. This also supports the businesses that are producing renewable carbon-free energy in Australia.

Dirty companies only have as much money as we give them

Using less means less revenue for the large energy generation, distribution and retail companies that, generally, are slowing the adoption of renewable energy technologies, and affecting public policy in negative ways. Make no mistake -- the combined actions of individuals is very powerful. The uptake of domestic solar PV has already had a huge effect on the energy generators and retailers in Australia.
This is because solar PV is usually producing power at precisely the times that energy is most expensive (energy retailers pay a fluctuating ("spot-") price for electricity,  and the times when the spot price is highest are the most profitable for the generators. Domestic solar PV is taking the edge from this demand, which is having a significant affect on the profitability of some of the big dirty producers. These kinds of commercial disincentives work to the advantage of renewable energy technologies.

If Australians continue to reduce their consumption and simultaneously install distributed generation (like solar panels, solar hot water, etc) and buy carbon-emission-free power, this will help to encourage the necessary changes. This will have a concrete effect on Australia's carbon emissions and reduce the likelihood of catastrophic climate change.

Remember, a carbon tax only has benefits because it causes people to use less -- we as concerned citizens can use less all by ourselves.

This post was written by Angus Wallace and first appeared at guesstimatedapproximations.blogspot.com.au