News of My Canadian Pharmacy

PV Fast Facts

It’s relatively easy to estimate the amount of annual output from a solar photovoltaic (PV) system, its comparative price with other solar systems, and its economics in terms of cents per kilowatt-hour (c/kWh).

Local Sunlight

Local sunlight is an important factor in the output and economics of a solar PV system. Electric output is essentially proportional to the amount of local sunlight, and cost is inversely proportional to output.

US Sunlight on a module at latitude tilt

US Sunlight on a module at latitude tilt (kWh/m2-day)

Solar maps are a good source of local sunlight. Here is one from NREL for the US, showing sunlight available for a fixed array pointing south at a tilt equal to its latitude, about optimal for such designs. You need a different map for one- and two-axis trackers for flat plates; and another one for concentrating trackers, which use only a portion of the light. But most installations are simply fixed tilt; or, in a few cases, large systems use single-axis trackers.

Our Excellent Renewables Adventure

renewablesPut simply, society doesn’t know much about renewables. It’s a vast vacuum of information, which shouldn’t be surprising, because renewables are a total paradigm shift.

The New York Times added some to the confusion with a recent article that baldly states that renewables are universally burdened with serious water issues. The truth is that some renewables are burdened with serious water use issues. But others are not. And one must add that conventional coal, natural gas, and nuclear plants are all burdened by serious water issues, to the point of drawing as much water as irrigation in the US (about one third of all water use, each). We know that water issues for electricity production are endemic.

But the point here is not to throw stones at the NYT, which is doing a good job with renewables and is part of the solution to our serious knowledge gap. And it isn’t to make renewables just a little less black than conventional electricity on water use, but to explain that we have only begun our journey towards a correct understanding of renewables, and there are some great renewable options that essentially do away with water issues. These select renewables technologies not only meet our climate and energy security needs, they do it while freeing up water for other uses. Water use will be a strength of our renewables future (hardly what the Times implies, I am sad to say).

Fast Cloud Transients

One of the thorniest issues that seemed to be facing large, utility-scale PV systems was sudden changes in PV system output due to the movement of single clouds on an otherwise sunny day. Now it seems that this issue has been resolved favorably, in an economical manner.

Figure 1 shows a particularly excruciating example of solar variability.

Figure 1. Worst case example of incident sunlight caused by the movement of transient clouds on a clear day (After Hoff and Perez)

Figure 1. Worst case example of incident sunlight caused by the movement of transient clouds on a clear day (After Hoff and Perez)

This kind of sunlight graph put chills down the spine of utility engineers and caused a major setback for the deployment of large-scale PV systems. PV output responds instantaneously to such changes. Such variability also compares unfavorably to solar thermal electric (STE) systems, which have natural thermal inertia, which damps out the sudden changes. STE system installers gladly took note and publicized the PV problem to everyone making a choice between STE and PV.

Getting Real on Wind and Solar

Getting Real on Wind and SolarPerhaps no recent article irritated me more and made me feel more vulnerable as a solar professional than James Schlesinger and Robert Hirsch’s Washington Post op-ed, “Getting Real on Wind and Solar” (April 24, 2009). The op-ed said we shouldn’t take solar and wind seriously, because they are unpredictable and cannot be turned on at will. There is a grain of truth to their statement. It is a serious criticism of wind and solar, and probably the most telling after the worst one – high cost. But I think it is because high cost is being overcome, especially in wind, that this next level of criticism is being raised. That’s progress.

I authored a response with Bundestag member Hans-Josef Fell, the co-author of the German feed-in tariff legislation (see Fell’s presentation at our kick-off symposium here). The Washington Post didn’t see fit to print it. Maybe they had not heard of the German feed-in tariff or its transformational importance to the global PV market.

An Unusual Comparison with Nuclear

We don’t burn solar modules to produce electric energy. If we are able to reutilize 100% of them forever, we would manufacture an unlimited amount of electric energy per gram of material. Even practicalally, we utilize less PV material per kWh than uranium per kWh when we produce PV electric energy comparing to nuclear electric energy. The active materials amounts utilized in PV are little tiny.

Just how little tiny? To receive an up and coming tenuous film, known as cadmium telluride (CdTe), we utilize about 12 gm of this substance to create a square meter module. In a year on the average US location, we obtain about 11% x 1750 kWh/m2-yr, or 154 kWh/yr (after suming for another 20% in deviation losses, but not for an additional, but small yearly loss). Thus during one year, we demand 0.08 g/kWh. But wait! We don’t burn PV modules, and they don’t die after one year – commitments are about 30 years, so this is really one thirtieth of that, or 2.6 milligrams per kWh. Let’s tabulate it:

Paula Mints on the Failure of Tenuous Films

photovoltaicsPaula Mints is a reputable delegate of the PV community elite. Her article in Solar Industry (November 2010) is not incorrect, it is just profound enough. Yes, to a high degree, tenuous film miscarried to modernize PV modules. But there are too many entertaining points to make out from her data to block there.

Perhaps Mints’ most conclusive tabular facts of the misfortune of tenuous films to modernize PV is her Figure 1, tenuous films share of total deliverables. She signifies that tenuous films’ share gone up in 1988 at 32% and gone down from there to 5% in 2004. Then it only picked up slightly to 17% by 2009. She didn’t take numbers from 2010, but push to the growth of Chinese silicon, tenuous film share may even go down in 2010. Is this the distinctive for a revolution?

The Cost of Solar PV

The Cost of Solar PVI get brassed off of constantly seeing ultramundane high prices for solar PV charged as the only possible price. You read this in articles from all sorts of media, and it is gulped by the slump and sinker. So how much does PV cost?

The response is “prices.” There is no real price, because there are many prices. Price differs by the local sunlight amount and by the system’s size and type.

And two types of prices exist– dollars per watt, which is price per momentary output. And cents per kWh, which is price per unit of energy imparted. Dollars per watt is difficult; cents per kWh is harder.

So with this in mind, let’s do some prices!

Great systems are cheaper than little systems; pocket-sized systems, like those on your house, are more expensive again. If we admit the greatest systems can be inducted (sans delays and all sorts of undefinable costs) at $3/W; then large rooftop systems on WalMart might increase the price for $4/W; and inhabited systems for $5/W. These would be “entire” systems, with no withholdings and other arrests. For more characteristic ones, you can supplement a dollar or even $2/W. These are all stationary mounts; if you wish tracing, supplement another 50 ¢/W to a dollar to the great system price (but you get 25% more output).

Solar Power: The Teddy Bear of Energy Sources

Originally posted at: Transition Voice by: Erik Curren
teddy-bear-294x300

Solar is so ingenious and pretty we can bearly make it stand firmly on the ground. But does this teddy have any teeth?

Is there a more encouraged sympathy energy source than solar energy?

Its fuel material is striken from the sun, which is comprehensible and accessible almost anywhere. It’s overwhelmingly pure to run. It’s easy to construct and sustain. The large support systems can utilize it to manufacture green grid power, but you can also place it on your own roof to become your own support system or to make it off-grid.

And did I point out that it’s maintained by THE SUN?

(Full disclosure: I do some work for a solar power company in Virginia knowns as Secure Futures).

It’s no surprise that public encourages solar power, with 92% of Americans in a 2009 poll claiming that it’s significant to work out solar energy sources. Particularly, environmentalists including My Canadian Pharmacy admire solar energy best of all amoung different energy resources. It’s as pure as wind power, but solar is much less questionable.

$/MT CO2

CO2I have never witnessed the inside of a computation of how much it is worth to evade CO2 utilizing PV. So I guessed I’d realize it myself and witness if it’s as terrible as some people seem to assume.

Now a watt of PV constructed for a year can manufacture from about 1-2 kWh/yr. Maybe that watt is worth $3 to construct. One kWh manifestured correctly in the US, by the EPA appraisal, is about 0.7 kg CO2 / kWh. So utilizing an average valuableness of 1.5 kWh/W-yr, we could admit about 1 kg/W-yr.

But this leaves behind two pretty important things – those kWh are prizeable; and there is a loan that supplements price to the PV. So for round figures, let’s admit the loan doubles the amount of money wasted on the PV; but the valuableness of the electricity payments the original amount. Voila, we are back where we began – $3/W of supplemented cost. This is obviously very complex! But it is conjectures like this that make all these computations ‘complex’.

The 20% Barrier, or Long-Distance Transmission Again

compressed air energy storageRecently, I cought hold of compressed air storage (CAES) as a devices of moving solar-generated electricity to night-time.

More recently, I pointed out that in far as wind was less expensive than PV, wind would be preserved at the first point in CAES.

Under the considerations that wind is less expensive than PV and wind gives blows more at night-time, we won’t be watching much PV preserved for moving to night-time.

It’s going to be difficult for PV to become less expensive than shoreward wind. Wind today looks to have about 50% more run-out per constructed watt than PV does. So that implies PV must be 2/3 of the price of wind per watt to be of equal value to it. If shoreward wind is about $2/W, then PV would have to achieve $1.33/W – maybe $1.5/W because wind has greater O&M prices. This is compact but ultimately likely about 2020. Even when it is reached, nevetheless, it only implies PV becomes about the same cost as shoreward wind is considered to be now. (Of course, solar is manufactured during the day, when it is more worth than wind. And PV is already about the same price as shoreward wind.)