Will Area/kWp within a PV technology decrease in the future?

[xiaoshir]

Hi, I'm new to PV industry, and I have a question on whether the area required per kWp within a PV technology (eg. c-Si, or thin film) decrease in the future? If it does, how was the historical development look like, and what would be the trend in the future?

[DanKegel]

Hi, I'm new to PV industry, and I have a question on whether the area required per kWp within a PV technology (eg. c-Si, or thin film) decrease in the future? If it does, how was the historical development look like, and what would be the trend in the future?

Sure, there is still some room for improvement.

For instance,

https://www.ise.fraunhofer.de/de/downloads/pdf-files/aktuelles/photovoltaics-report-in-englischer-sprache.pdf

says

"In the last 10 years, the efficiency of average commercial wafer-based
silicon modules increased from about 12 % to 16 %. At the same time,
CdTe module efficiency increased from 9 % to 13 %.

In the laboratory, best performing modules are based on monocrystalline
silicon with about 23 % efficiency. Record efficiencies
demonstrate the potential for further efficiency increases at the
production level."

[xiaoshir]

Hi, thanks for quoting the Fraunhofer report. This is actually where I got confused. I thought efficiency as the electricity produced divided by the solar energy hit on the modules. When efficiency increases, it means more electricity will be produced. But the capital BoS cost per Wp will not be changed right? It is just when LCOE is calculated, the denominator (electricity) will be larger so the BoS cost per kWh will be smaller. But I have read a Fraunhofer report (current and future cost of PV), it was mentioned that the BOS area-dependent capital cost will be reduced by higher efficiency in the future. I thought the capital cost will only be reduced when less area is required per Wp (m2/W is smaller), which I understand as a different parameter, not efficiency.... I feel I must have misunderstood some very basic things here. Could you explain it to me? Thanks!

Sure, there is still some room for improvement.

For instance,

https://www.ise.fraunhofer.de/de/downloads/pdf-files/aktuelles/photovoltaics-report-in-englischer-sprache.pdf

says

"In the last 10 years, the efficiency of average commercial wafer-based
silicon modules increased from about 12 % to 16 %. At the same time,
CdTe module efficiency increased from 9 % to 13 %.

In the laboratory, best performing modules are based on monocrystalline
silicon with about 23 % efficiency. Record efficiencies
demonstrate the potential for further efficiency increases at the
production level."

[DanKegel]

Can't help you there, too many words

But I do think BOS costs per module will decrease a little bit as time goes down, too. Australia has them much lower than the US, for instance.

Are you more interested in utility-scale, or rooftop?

[xiaoshir]

Yes. I think so too that the BOS capital cost will be reduced, but not as much as module cost. To simplify my previous post a bit: I'm just not sure about the reason, Fraunhofer says it is because of efficiency, which I don't understand. I think only the reduction of m2/W will reduce BOS capital cost, not efficiency.

[SunEagle]

Yes. I think so too that the BOS capital cost will be reduced, but not as much as module cost. To simplify my previous post a bit: I'm just not sure about the reason, Fraunhofer says it is because of efficiency, which I don't understand. I think only the reduction of m2/W will reduce BOS capital cost, not efficiency.

Efficiency is just one factor related to cost. Another main ingredient to a lower cost is the material of the pv cell and how much it costs to manufacture it.

That is one reason why some researchers went down the path of thin film solar cells. The material is less expensive then silicon and the cost to make the thin film cell is less then a mono silicon type.

The problem is that thin film is less efficient then silicon pv cells. So if you get the production costs down or the efficiency up is the path to reduce the price.

[solarix]

Actually, solar technology is fairly mature and the major advancement that has happened is the manufacture of it has become highly automated. Major improvement will come not in efficiency gains but in the reduction of all the "soft costs". Current equipment costs are about $1.25/watt wholesale whereas many areas in the US are still paying $3.50 to $4.50/watt installed. While I'm sure that all the construction trades experience the onerous hand of 14,000 building departments, if we want to get the cost of solar down to where not just the eco-elite can afford it, we need to simplify and streamline the permitting processes. Already, in places like Vermont - permits are waived for solar and just a simple registration is used to inform the utilities of solar installations.
Although the use of open flame causes 69% or over 255,000 home fires per year in the US, while the occurrence of fires due to solar systems is negligible, we see a concerted effort by the code authorities to restrict the ease of installing solar, while being satisfied with the current standards for open flame basically amounting to "be careful". Tradition is hard to change while new technology is easy to restrict.

[inetdog]

The standard cost metric of dollars per watt of nominal output does not depend directly on panel efficiency.
The area required to produce a particular amount of power depends directly on the efficiency and so is important where you have a limited area to work with and need to maximize output rather than minimize cost per watt.
Increased efficiency does not lower the cost per watt unless the additional efficiency is not associated with a higher cost. Initially the more efficient panels will cost more either because the production process is more expensive or because the market allows a premium price. The balance between these two factors for SunPower panels is up for speculation.

[xiaoshir]

Efficiency is just one factor related to cost. Another main ingredient to a lower cost is the material of the pv cell and how much it costs to manufacture it.

That is one reason why some researchers went down the path of thin film solar cells. The material is less expensive then silicon and the cost to make the thin film cell is less then a mono silicon type.

The problem is that thin film is less efficient then silicon pv cells. So if you get the production costs down or the efficiency up is the path to reduce the price.

When you say "The problem is that thin film is less efficient then silicon pv cells", what do you mean by efficiency? The module conversion efficiency or m2/W? or both? This is the main confusion I have got.

[xiaoshir]

The standard cost metric of dollars per watt of nominal output does not depend directly on panel efficiency.
The area required to produce a particular amount of power depends directly on the efficiency and so is important where you have a limited area to work with and need to maximize output rather than minimize cost per watt.
Increased efficiency does not lower the cost per watt unless the additional efficiency is not associated with a higher cost. Initially the more efficient panels will cost more either because the production process is more expensive or because the market allows a premium price. The balance between these two factors for SunPower panels is up for speculation.

I have thought about the same: "Increased efficiency does not lower the cost per watt" but cost per kWh. But Fraunhofer did a study that says below. Basically their standpoint is that, if the target is to produce the same amount of electricity, then the smaller area would be required, so the area-dependent component of the BOS cost will be reduced, which I agree, if we are talking about BOS total investment cost.

Untitled picture.jpg
"Module efficiency was identified as the single, most influential factor on BOS cost. Figure 27 illustrates the effect of increased module efficiency. Today, the area of a PV power plant with 1 MW power and 15 percent module efficiency is comparable to the size of two soccer fields. By doubling the module efficiency, the surface would shrink to 50 percent which equals one soccer field in our example of a 1-MW power plant. Consequently, all area-related costs like the installation or the mounting structure in the power plant would be significantly lower. Assuming that exactly the same setup is chosen for a 2-MW PV power plant with modules at 30 percent efficiency as for a 1-MW PV power plant with modules at 15 percent efficiency, the specific area-related cost would even be exactly 50 percent lower in the case of the higher efficiency modules: cost for installation, mounting structure, fencing and roadwork would beidentical between the two power plants, yet one having an output of 2 MW and the other an output of 1 MW."

Again, I fully agree with this part above, but they then reduce the $/kWp of BOS cost because of efficiency improvement (see below), which I don't understand, since I thought $/kWp would be the same. Since with improved efficiency, both area and number of kW required are reduced, which results in the same BOS cost per kWp. Do you think I'm right about this?

Untitled picture1.jpg

Source:https://www.ise.fraunhofer.de/en/pub...ale-pv-systems , page 37 and 41.

[xiaoshir]

The standard cost metric of dollars per watt of nominal output does not depend directly on panel efficiency.
The area required to produce a particular amount of power depends directly on the efficiency and so is important where you have a limited area to work with and need to maximize output rather than minimize cost per watt.
Increased efficiency does not lower the cost per watt unless the additional efficiency is not associated with a higher cost. Initially the more efficient panels will cost more either because the production process is more expensive or because the market allows a premium price. The balance between these two factors for SunPower panels is up for speculation.

Hi, you are making a very good point here. When I searched for the module cost future projections, many people are projecting that by around 20% learning rate, meaning that the cost of module will be reduced as we produce more. But at the same time, the efficiency of modules are improving, which will increase the module cost, as you mentioned "production process is more expensive or because the market allows a premium price", but many people don't consider this. Which one do you think is more significant in the module future cost development?

Do you have any idea on how much the cost will be increased if we just consider efficiency improvement, and how does that compare with the historical 20% learning rate which drives the cost down?

[SunEagle]

When you say "The problem is that thin film is less efficient then silicon pv cells", what do you mean by efficiency? The module conversion efficiency or m2/W? or both? This is the main confusion I have got.

A solar cell efficiency is measured by the amount of power (electron flow) it can generate when a measured amount of sunlight strikes a specific measured area or m2/w. A 6" sq mono silicon cell of certain properties are being manufactured to have a 23% efficiency rating while a 6" sq thin film cell might be only 15% efficient. (Those % numbers keep changing but thin film still lags behind mono)

The cost of making a 250 watt panel consisting of thin film cells is less then a 250 watt panel with "mono" cells but that difference in cost does not yet overcome the higher efficiency of the mono panel. And a mono allows you to make higher wattage panels using the same area taken up by thin film cells.

You can increase the cell "output" using magnifying lens that concentrates the light on the cell, or multi layer cells (captures more photons in the second and third layer that pass through the first layer) or even double sided cells (capture light that is reflected off the surface behind the panel). All those tactics just add to the cost but do not necessarily make the panel cost efficient.

When I was involved with thin film Cadmium Sulfide research (early 70's) I found a way to reduce the sheet resistance of the cell that would allow more electrons to be harvested which increased the cell efficiency. Although the new manufacturing process did not increase the efficiency enough to make it a viable product. Also all type of thin film cells have the problem of losing efficiency when they get too hot.

The science of finding a cheaper material than silicon to make the cell that will result in a high % output is still in the works.

[xiaoshir]

Question answered!

Now I think I made a mistake by mixing the kW of solar energy hit the PV and the kW of power output from PV in my previous posts. The power output in kW from PV will be the same (as opposed to being reduced by half as I mentioned) after efficiency is improved, and the same amount of electricity will be produced per kW. It is only the area required will be less, which results in reduced BOS cost per kW. In general, the m2/kW is always negatively correlated with efficiency, and reduces when the efficiency increases. These two factors make the electricity produced per kWp always the same, which I didn’t realize. In general efficiency improvement means more energy is produced per area, not per kWp.