Hi Axel,

In technology, sometimes we want to be simple and do away with complex sciences. The case of solar energy best illustrates this.

What I am saying is at the practical level, the engineers and technicians should not be arguing about how to measure a panel effiency and not agreeing to anything. So this is simplified with the 1000W/m2 value. Thus the output based on a lab model sunshine is considered as the practical capability of that unit. Thus when that particular is used on site, another factor has to be used to show the real output.

Well this is my take.

As for the deep physics of the solar panels, let the researchers deal with it. So your questions are really relevant to these researchers. May be in a few years time we will have a totally new concept of harvesting the solar energy.

Hail the researchers!!!

Wan Zaidi 

Dear Wan Zaidi,

thx for your input - maybe we can reduce the few years time to only several months as we are already testing newly developed equipment (yet under patend pending procedures) with regular PV panels showing exciting results in energy transformation  in quantity as well as in speed.

Time factors - i do believe - are also of essential importance - well for understandable reasons they are missing in the 1.000 W/m² "standard", and I am talking s, not even s².

kind regards,

Axel

Solar energy is to variable. It is useful to work with 1000 W/m2 considering that this amount is taken for Standar Test Condictions. But for any simulation it is necessary to work at least with  local climate data

Solar energy is to variable. It is useful to work with 1000 W/m2 considering that this amount is taken for Standar Test Condictions. But for any simulation it is necessary to work at least with  local climate data

Solar energy is to variable. It is useful to work with 1000 W/m2 considering that this amount is taken for Standar Test Condictions. But for any simulation it is necessary to work at least with  local climate data.

Kind Regards

Esteban

The generation of electrons in PV cells is a function of the wavelength of light. In other words, the amount of electrons generated when a PV cell receive UV radiation is not the same as when visible light falls on it. The question then comes: Assuming that more electrons can be generated by whatever other means, how significant would that generation be when compared to the already well established knowledge. If it is 1% more then it is small but if it is 10% or more then I can already feel my ears tingling and my eyes growing big.

This value of 1 kW/m2 (aka 1 sun) is arbitrary but obviously easy to remember and useful due to its simplicity and unity. It is also a typical value in a number of circumstances, at least over sunny areas. This value is on the high side, i.e. for situations around noon under clear conditions. Values significantly larger than this (by more than 10% or 20%) are actually infrequent, if not exceptional. Values of global horizontal irradiance up to about 60% larger have been recorded, but they are transient values lasting only a few seconds, which can only occur under extremely rare circumstances...

Dear Charles,

I assume by saying the generation of electrons you mean the transition of orbits of the "energized" electrons.

Taken into consideration that photons hit approx. every 10th Billion electron or electron position and have them switch their positions thus producing the harvestable energy when pulling back into an empty "defect" electron position I would  suggest that the minimum rate would be a doubling in the harvest effect only due to the effect that there are other particles capable to produce the same or comparable effect like photon/electron. The first particle in question would be of bosonic nature, obviously Quarks and different fermion stati rush through the cells in massive quantities too.

There are some other interesting effects, which we were able to test them reproduceable, and there is need to have time factors calculated as charge, hence integrated within the algorithms.

To sum it up it certainly looks that a doubling of the efficiency ratio percentage is possible.

Dear Axel,

Standards are there to help the customers and manufacturers to deal with complex/controversy metrics. As mentioned above, daylight is not a fixed value and you need to have a norm in order to valuate the device that the manufacturer is selling (is price), Power density is only one of the parameters where you need to add spectrum, homogeneity and stability as criteria as well (apart of all accuracy calculations and the traceability to the primary calibrated cells). Having a norm allows also to perform indoor measurements. Of course, a norm can be changed in case of need but I do not think that a norm is preventing research to go ahead! By the way, just imagine to change right now this norm... what will happen with the ca 100GWp PV installed capacity? Who will bare the costs to prequalify all those modules?

Dear Ivan,

thank you - very good points - I am drawing my attention to the problematics of marketing explanation needs as well as to industrial comparing standards too - I am also aware of the effects of a big leap in technology (that is neccessary and that will come)  on the existing business models.

Having in mind the exisiting scenarios we decided to integrate the technology not directly into PV cell and materials structure but to offer it instead as an addon to allow for existing installations to "upgrade" or as we would see it from a marketing point of view: "chiptuning for PV installations".

I would suggest that this could improve the viability of existing models or might even open the chance to reduce governmental subsidies on the kWh models. Hence still leave existing profit margin calculations at level - allowing for a switch from "price model" to a quantity-availability model. Obiously the price per kWh increases if it can be delivered when needed and not when produced. This calls for a neccessary integration of storage capacities directly at the point of production (at low cost level) - which is an integrative part of our model.

kind regards,

Axel

Is there any specific reason that the Standard test condition (STC) for most of the PV panels are 1000 W/m2? why not 750 W/m2? The historic National Renewable Energy Laboratory demonstrates that in most cases the real solar irradiance level is in the range of 500-800 W/m2, so why the STC should be 1000 W/m2? Why the PV panel ideal operating point is set to this irradiance level? 

Dear Mohammad,

true - this is a very good question - and I do believe the simple answer is - due to marketing and sales reasons - because every non-technician can divide any Integer smaller than 10 or 100 or 1000  and come up with a simple efficiency ratio that would sell the product.

As we all know the time factor is not integrated in the solar irradiation digit, while it is in the output of the panels: e.g. 1kW vs. 150Wh or as I like to say 0,15kWh ..

From the point of view of Quantum Electro Dynamics the efficiency ratio of the panel, I believe, must be around 0,000 something % or even less.

But then - nobody would understand the calculation and, even worse, nobody would buy such a product.

pls also referr to the Chris and Ivan answers to the question posted earlier.

Chris Gueymard: "This value of 1 kW/m2 (aka 1 sun) is arbitrary but obviously easy to remember and useful due to its simplicity and unity."

Ivan Sinicco: "Standards are there to help the customers and manufacturers to deal with complex/controversy metrics."

kr.axel

Thank you Axel.

The standards are given to make the comparison between different brands easy.  They give thumb approximation for the required area. But however, in detailed study the local data must be used.

Dear Axel,

You bring quite interesting questions. Your question concerns the conversion methodology of the solar radiation into electricity. At first we have to be aware the incident solar radiation on the earth surface appears as if it is coming from a blac body heated to about 6000 K. So, the source of radiation has a very wide spectrum peaked at the visible wave lengths. This received radiation is electromagnetic in nature and it is composed of photons whose energy is inversely proportional to its wavelength.

So, it is found that these radiation behaves as electromagnetic waves during the transmission while it behaves as energy quanta when interacting with materials.

But one has not to forget that its origin is the black body radiation!

There are to methods to convert this radiation to electricity: the direct method by photo voltaic effect and rectantenna or by thermo electric conventional thermodynamic machines.

The problem with the first method specifically the photovoltaic is to find a material or even a combination of materials that can absorb directly and convert all photons into electron hole pairs especially the infrared radiation. May be the concept of tandem cells approaches slowly the target. whoever the cost gets higher.

The conversion of solar energy to heat  requires black body absorber which are capable to absorb all the incident solar radiation and converting them to heat. If you could make totally absorbing surface it will be heated up by the incident solar radiation and begins to remit again once its temperature is above the environment temperature. In addition the kinetic energy of the heated fluid will not totally extracted by thermodynamic machines. One may recycle the heat to raise the conversion efficiency which may render the system more expensive.

May be the recantenna deliver a more efficient conversion efficiency but this technique is still in the very beginning phase.

I hope i could introduce some slight contribution towards answering your question. 

Wish the best Axel!

Dear Prof. Zekry,

totally agreed - now my questions would continue like this:

We agree on the photovoltaic effect of photon to electron energy transformation.

... whereas all of the above mentioned particles are of bosonic nature.

I think the "efficiency ratio [eR]" is one thing - the total available basis to harvest from is another thing. In increasing the basis maybe the eR even is beeing lowered but for the same cost the output might have been increased.

Dear Axel,

I hope that i understood well your questions.

Concerning the first question in the list, there is trials to make full use of the infra red radiation which have photons with energies smaller than the band gap. These photons are absorbed by thin layers of materials that combine them and release them in photons with energies equal or slightly greater than the band gap. These materials are called frequency upcconverters. For more information please se the paper:https://www.ise.fraunhofer.de/de/veroeffentlichungen/konferenzbeitraege/konferenzbeitraege-2014/29th-eupvsec/goldschmidt_1ap.1.2.pd

Concerning the second question, it is so when the photons falling in the material they transfer their energy to the electrons but unfortunately the excess energy above the conduction band edge will be lost as heat in  a process called thermalization. In order to overcome this losses one tries to used the so called down converters which converts the excess energy into photons that can be useful. For more information about the down conversion of the UV radiation please see the paper in the link:

www.kps.or.kr/jkps/downloadPdf.asp?articleuid=%7B23035A8B...

Concerning your third question in the list:

Sure the conversion efficiency will be higher and the pea watt generated from the same incident solar radiation will be higher. How much this is the matter of advancements in Technology. The basic science deliverers us the concept and the limits of the process but there must be a tremendous efforts to arrive there.

wish you the best