Solar panels

Whether solar PV is environmentally beneficial depends on whether it covers the energy cost to produce the system to produce and deliver electricity (not just the panels).

With the technology available in 1970s the energy cost was certainly high. Someone (probably a physicist) said that "solar cells are just canned petroleum energy". It was perhaps a fair comment then. And many science-oriented people think that what was true in 1970s must still be true. But, thanks to evolution of basic science of solid-state physics, the technology changed very much. Experts at a Japanese national institution say that the energy pay-back time of recent solar PV systems is around 2 years.

But peripheral things matters. As a leading engineering professor remarks, the energy cost will be considerably higher if the stand to hold PV panels is made of aluminium, which is virtually re-packaged electricity. It is surely low if the existing roofs are used without reconstruction.

It is a good solution to reduce the bill cost. In Germany most of DMs use solar panels.

I put in a 4.68Kw PV system 1.5 yrs ago. After the rebate and tax credit my net cost was $9,500 (US). I installed the system myself, so that cut the cost in half. My annual electric bill was $2,100 prior to install. After the first year it was reduced to $340, Therefore my system should pay for itself in a little over five years.

People will not have difficulties with their humanities essays creating, because the papers writing companies can sell essay of premium quality.

Rather than 'ecological benefit' (whatever that is), measure it in terms of kgs of CO2 avoided. (There is an additional benefit for not burning coal.) This is much harder to determine than one might first suppose. Indeed, it is probably much less than one might first suppose based solely on kWh generated. The difficulty is in the additional variable generation of the balancing agent (i.e., backup).

If there are very few solar PVs installed, the additional variability can be neglected. As the number of installations grow so does the additional variability.

[In fact, working out the CO2 avoided is easy - because the little meter tells you. Of course, it may not speak sooth -W]

Whether solar PV is environmentally beneficial depends on whether it covers the energy cost to produce the system to produce and deliver electricity (not just the panels).

With the technology available in 1970s the energy cost was certainly high. Someone (probably a physicist) said that "solar cells are just canned petroleum energy". It was perhaps a fair comment then. And many science-oriented people think that what was true in 1970s must still be true. But, thanks to evolution of basic science of solid-state physics, the technology changed very much. Experts at a Japanese national institution says that the energy pay-back time of recent solar PV systems is around 2 years.

But peripheral things matters. As a leading engineering professor remarks, the energy cost will be considerably higher if the stand to hold PV panels to the right direction is made of aluminium, which is virtually re-packaged electricity. It is surely low if the existing roofs are used without reconstruction.

[The rails that the panels sit on look like extruded Al (see e.g. http://www.flickr.com/photos/belette/6443632385/in/set-7215762797900593…). The brackets connecting those to the roof are solidish steel -W]

William, should be solat, or solar?

[Hmm, not sure how I managed that, but now corrected -W]

And what about the low albedo of solar panels? ;-)

Interestingly, there were some protests in China regarding solar factory (70 % of all solar panels is made in China), because of polluting nerby river, more on protest in China here:

[Should that me nearby ;-? Our Trina panels are from China -W]

Back in September, massive protests outside a solar factory in eastern China forced authorities to shut down the plant, which had been accused of contaminating a nearby river.

http://www.businessinsider.com/haimen-china-protest-power-plant-2011-12

Alex

Yeah, nearby :-)

Little bit OT, but not so much, given the effort to reduce our collective GHG footprint..

Stuart Staniford seems to be less worried about (worsening, or overblown?) methane situation than prof. Ugo Bardi (both coming from the peak oil camp), sees Ugo's reaction here:

http://cassandralegacy.blogspot.com/2011/12/history-of-humankind-in-six…

Alex

[I'm not sure the "Arctic methane emergency group" can really be trusted. It includes Andrew Lockley, who I presume is this one which is Bad (check contribs). For the moment, the best guide is actual methane concentrations -W]

- I meant to look into it too, but too late now.

Overall, I think it is a good idea to withdraw the scheme - I think it is pretty clear that Fossil Fuel generation + carbon tax (even at Stern levels) would be currently cheaper than Solar.

[I would certainly support a carbon tax, and let the market sort out the How and What, rather than the government picking the subsidies. However, since we don't have one, that isn't an argument for reducing the subsidy now. My main argument for doing so is the governments one - that the subsidy is too lucrative -W]

I think this is why it is better applying a carbon tax rather than governments 'picking winners' - there is probably a whole stack of stuff that is marginal, that when you apply a carbon tax - would trigger a move away from fossil fuels - but I don't think Solar is there yet

"In fact, working out the CO2 avoided is easy"

Then it's simple.

CO2 avoided x Stern value of social cost of CO2 (8 US cents per kg). If this is greater than subsidy then it's fine. If less then we're wasting resources which is most unecologic.

As an example, the number from a year or so back in Germany was $1070 per tonne CO2 not emitted as against that Stern cost of $80. Pissing money away and thus wasting resources.

I'm one of those who think that solar will get there, will actually be cheaper than coal even ignoring externalities, but it ain't yet.

[I was joking, though. The device tells me the CO2 avoided, but presumably it is making some assumptions about the UK generating mix. I could have signed up to use Nukes only in which case my CO2 avoided is ~0. Or something -W]

You obviously got it installed by 12th Dec. I imagine last 6 weeks were rather fraught for installation companies with customers very anxious about installation dates. Were you close to 12th and did this cause concern for installation date?

[There was some concern, especially as a couple of things needed fiddling and reduced our time margin. In the end, we had our work finished by tuesday, our certificates by wednesday, and I was going to mail them in on thursday but they turned out to accept email so that was less hassle; and the deadline was the next monday -W]

I am expecting that we will get 50% of generated electric sold to grid at 3.1p/KWh making payments effectively 44.8p/KWh generated. They don't meter usage just meter the generation and assume 50%. If it is connected to grid I cannot see any reason not to opt into scheme so hopefully supplier guided you to tick the box on the forms. If you failed to tick the box to opt in, I think there were annual opportunities to opt in or out.

I think you should be able to get 3.92KWp system for about £10k and less than that after April. I paid ~£10.5k and subsequently saw advert for £9950 but prices probably rose approaching 12 Dec.

So you can tell that I think it is clear that the 43.3p subsidy is sufficiently lucrative to allow the installation companies to get away with charging a high rate for their services.

After the subsidy reduction, competition between the installation companies to survive might be interesting. I wonder how low the installation element of the cost will fall.

[Agreed. I expect panel prices will fall (I think they are ~60% of the cost), and people could get more efficient -W]

The aluminum in the frames is of course, highly recyclable with minimal additional energy inputs, so you are really just borrowing the cost of smelting the aluminum for perhaps thirty years or so. Other factors like corrosion resistance affecting estimated lifetime probably make aluminum the best choice.

Here in Manitoba, Canada, our electricity rates are very low - 6.5 cents per kWH for domestic use, which makes solar unattractive. Payback times for small solar installation would be at least 25 years even with zero interest cost. Ontario has subsidized small to medium renewable energy tie ins with guaranteed rates up to ten times commercial rates which has led to farmers plowing under orchards and vineyards and paving them with solar panels. I have my doubts this is overall a smart move.

[Um, but don't forget that what makes my panels attractive isn't the electricity cost either - its the subsidy per kW generated, which is entirely independent of use -W]

Solar makes sense where mains electricity isn't available. We use it for powering electric fence energizers, many cattle farmers use it for pumping water for cattle on remote pastures. I know a small ISP who has a number of hilltop wireless relays powered by solar, and I'm sure it is a boon for the third world for things like lighting and battery charging for cell phones and radios.

At present, the low-hanging fruit is energy conservation, everything from mass transit to energy-efficient cars to retrofitting buildings with better insulation to reduce heating costs. Just my opinion of course.

Of course if one used solar electricity to make the aluminum, and all the components, the CO2 costs are entirely different. This is where I get completely confused.

>{Agreed. I expect panel prices will fall (I think they are ~60% of the cost), and people could get more efficient -W}

16 of these 245W panels (the ones I got, made about 14 miles from me)
http://www.swithenbanks.co.uk/Solar_Photovoltaic_Equipment/294/product…
at £310 each inc VAT is less than £5k and I wouldn't be at all surprised if solar installers get some volume discount. So panels already under 50%.

Re People could get more efficient. Hmm, at doing the installations or at remaining MCS accredited rather than becoming accredited and similar? I think there is more in the pricing of the labour than in the hours per installation.

[Our people could have scheduled things a bit better - they used more electrician time than was really needed (see-also http://www.flickr.com/photos/belette/6466637459/in/set-7215762830696642…, showing them putting the meter in the wrong place to start with). Scaffolding time must be a cost, too - not sure how that can be improved -W]

I put in a 4.68Kw PV system 1.5 yrs ago. After the rebate and tax credit my net cost was $9,500 (US). I installed the system myself, so that cut the cost in half. My annual electric bill was $2,100 prior to install. After the first year it was reduced to $340, Therefore my system should pay for itself in a little over five years.

When calculating the kgs of CO2 saved, you shouldn't use the average of the energy mix rate. When renewables go on line, they displace the most expensive other supplies. These generally tend to be the most inefficient and probably the most polluting. However, as it's a free market, you can't be sure. For more details check out the Merit Order Effect.

BTW: I live in France and there are subsidies for home installations in the form of tax breaks. I was interested in a system a couple of years ago but not being in a position to fully benefit from the tax breaks I looked at getting an installation outside of the subsidy scheme. I looked at systems from the UK, Belgium, the Netherlands and Germany as well as France.

I easily got quotes for systems with subsidies, but not for unsubsidised sytems. I was mildly amused to find that if I subtracted each countries' subsidy from the price in that country I arrived at similar figures across all the countries.

What concerns me, from a "sustainability" aspect, is the mandates that power companies buy this electric power from people.

It is an odd scenario where someone must buy a product due to government mandate.

Who pay for those buying the power?

Other customers through higher rates. Will that encourage a massive number of people to buy solar panels? It seems to me that this would eventually reach a point where the power company couldn't pay for the solar energy anymore.

They would have to raise the rates incredibly or the government mandates would have to be abolished.

I mean, it is nice for the people with solar who can sell the energy during the day at a premium and get fossil fuel energy at night in exchange, they get a cheap bill, subsidized by poorer people who can't afford solar systems, but I don't think it can be scaled up effectively.

[Not sure what you mean. The power companies buy power back at a much lower rate than the rate we pay for power, as I said -W]

> Scaffolding time .. not sure how

Some simple arrangements: First, which we used, is get together with neighbours and order at same time offering the benefit of minimal movement of scaffolding. If you are lucky and they don't want to find the £10k, you rent their roof in order to double your investment. I wasn't that lucky.

Second would allow homeowners to fit rails themselves to reduce installation cost but that may involve more accidents and take more time.

Third each gang to own their own scaffolding, preferably after job going to a gang-members home rather than extra journeys to the company's premises. Probably with some extra company scaffolding to cope with 3 stories .... I believe our installers owned their scaffolding and trailer.

Even if unnecessary for a bungalow, I wouldn't be too surprised if time putting it up may be saved in carrying out work.

AIUI scaffolding time is pretty cheap, it is the (dis/)assembly that is risky and expensive. Making sure assemblers are going to be using it seems to be one risk reduction strategy.

Solar PV tends to displace first, natgas burners and second, coal burners.

William, congratulations !
You are ahead of me here. Here in California, your panels will probably generate more power (even today, we had bright sun and clear skies) so we could have made a deal where you pay for my panels and I pay you back the savings ;o)

[That is a fair point, though you wouldn't have been eligible for our subsidy. Some people have been getting them installed on west-facing roofs, because that is what they have. Undoubtedly the same panels, in California on a south facing roof, would generate double the power; that would be far more sensible, in an ideal world -W]

Uptil last year, the utility company here also would not pay you anything for the kWhs you generate in excess of your usage. However, the law changed here in California, and you now get residential rate paid for every excess kWh generated. This is done on a yearly basis.
Either way, I still think that solar power could only become economical if done on a large scale. Installation costs (with people climbing on your people's roofs, with each roof being different and such) simply will always be much more costly than simply lining up thousands of panels in the Mahovi desert.

[Very likely. Roofs are used just because they are spare (though for new-build, the scaffolding costs disappear, and indeed you should be able to save on tiling costs). We have no empty deserts, other than Slough, to put our panels in. I've seen semi-serious proposal to put the panels in the Sahara, and xfer the power back (cables, or as hydrogen) -W]

Roofs are used because they are spare, but also because they do not require new transmissions lines and rights-of-way, as do some utility-grade solar farms. THer is plenty of room for both, and of course, new construction is easier.

Commerical roofs are easier, and one finds panels sprouting around Silicon Valley on roofs and over car parks.
The latter is a triple win:
1) Generates electricity.
2) Keeps cars cooler.
3) Asphalt parking lots can get hot, making a little heat island around the building, thus making air conditioning work harder. Solar panels over parking lots lessen this.

If starting from scratch, here's a very cool NASA building.

Of course, climate differences matter, and optimal solution mixes vary radically.

There may not be deserts in the UK, but East Anglia is not short of flat land. There's a 5MWp solar farm out at Wilburton, north of Cambridge, and another being built at Chittering.

"we could have made a deal where you pay for my panels and I pay you back the savings"

Three cheers for offsets!

Way to go. You're now in the running for this year's Exemplar of the Bottom Up Walk the Walkers. The price of the fossil fuel externalities your installation prevents should factor into your economic calculations. Also, there is a real economic value to the fulfillment of your desire to do something beneficial for climate and/or be on the cutting edge of technological progress.

We have no empty deserts, other than Slough,

Seriously? Have the friendly bombs fallen at last?