Concentrated Solar Power with multijunction cells

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jbauer
Concentrated Solar Power with multijunction cells

Hello! Do you have a SAM case using concentrated PV and thermal with Frenel lenses and multijunction cells in flat panels installed on dual axis trackers? If not, is it possible to use any other existent case to get an approximate result?
Thanks indeed for your answer,

Jorge

Stefan Troger

Hello!

I´m working on a similar project as jbauer mentioned and I also have a few questions to it.
My problem is that i want to enter specific module databases or electrical specifications from a triple junction cell.
Similar to the Specifications I can enter in detailed photovoltaic projects with CEC Performance Model with User Entered Specifications.
The main problem is that the maximum power (Pmp) doesn´t match with the specifications I got from the cell datasheet.

Is there a possibility to enter cell specifications from a datasheet in high concentrated photovoltaic projects?
Why is the maximum power (Pmp) in HCPV projects calculated by Irradiance, efficiency and losses and no electrical data are included?
Is it representative if I put my electrical data of the triple-junction cell in a detailed photovoltaic project?

BR Stefan

Paul Gilman

Dear Jorge,

SAM does not have a model that combines thermal and photovoltaic collectors. I don't think there is a way to model the kind of system you describe.

Best regards,
Paul.

Paul Gilman

Dear Stefan,

SAM's HCPV model is a relatively simple representation of the performance of a high-concentration photovoltaic collector.

SAM does not have an equivalent to the CEC performance model for flat-plate modules. The equation for the HCPV Pmp value is in the Help system, so you should be able to use that information to approximate the module you are trying to model.

The cell efficiency table is the only information the model has about the module's electrical performance.

Best regards,
Paul.

nkabouche
nkabouche's picture

Dear Paul,

I would like to use SAM to determine the net DC power that an HCPV system and a PV system could produce in a specified site. So, I have some question and assumption:
- Is the tracker in HCPV, by default, a 2-axis one?
- I presume that this HCPV is a point focus one, with Fresnel lenses;
- In the result of simulation: what is the difference or relation between Input radiation (kWh) and POA on cell (W/m2)?
- Does the value given, by default, to the module correspond to a real HCPV, if so what is it
- How can I use an existing HCPV data e.g. SOITEC CX-M500 CPV, especially the cell efficiency table

Best regards

Paul Gilman

Hello,

1. Yes. SAM's HCPV model assumes that the tracker is 2-axis with no limits to the extent of its rotation.

2. The model makes no assumptions about the type of concentrator. You provide the concentration ratio with loss factors to describe its optical characteristics.

3. The input radiation is a value SAM reports for reference. It is not used to calculate the system's output. It is calculated as Input Radiation = DNI (W/m2) * Module Area (m2) * Number of Modules per Tracker * Number of Trackers / 1000 (W/kWh) . The POA on cell value is the irradiance incident on the cell adjusted by air mass modifier, soiling, shade derate, optical error and alignment error.

4. No. The default values are a starting point for your analysis, and are not based on a specific system.

5. To model a commercially-available collector in SAM, you will need data from an efficiency curve from the manufacturer or another source.

Best regards,
Paul.

nkabouche
nkabouche's picture

Dear Paul,

Thank you very much, I found this HCPV module (http://www.arima.com.tw/en/group1-detail.php?index_m1_id=1&index_m2_id=2...) but they did not provide the differents losses and error
we have the cell efficiency (>39%) and the module efficiency at STC (27%);
Is it possible to use these value to adjust these factors?
Or do you have these data for an existing cpv module?

Best regards.

Paul Gilman

Hello,

The default module is a good starting point to see what the data should look like. There is not enough information on the Arima data sheet to provide all of the inputs SAM requires, but you may be able to approximate it by using the cell efficiency they report (39%) as the reference efficiency, and adjusting the cell area, number of cells, and loss factors to achieve the maximum power they report.

Best regards,
Paul.

nkabouche
nkabouche's picture

Dear Paul,

Another question is the two axis tracker powered by the HCPV or by an independent source?
is there a bibliographic reference that SAM relies on for HCPV?

Regards.

Paul Gilman

Hello,

SAM assumes that the system is always connected to the grid, and reduces the AC "System power generated" to account for the require tracking power. You can see this by making a copy of your case (click Duplicate on the Case menu), and setting Single tracker power (fraction of DC nameplate) on the Array page to zero. Then run a simulation, and on the Time series tab of the Results page, compare the "AC gross" and "System power generated" values of the two cases to see the impact.

Unfortunately, we do not have documentation of the HCPV model aside from the information in the Help system, and content of discussions on this forum.

Best regards,
Paul.

Princess_Zaynab
Princess_Zaynab's picture

Hello Paul,
I want to ask a question about input "Cell Efficiency".
You are saying that we can have it from a data sheet from the efficiency curve.

When I look at the efficiency curves of the data sheets, efficiency curve is often in function of sun concentration not DNI.
Can we consider that it is the same thing?

Thanks in advance for your answer,
Z

Paul Gilman

Dear Zaynab,

In SAM, you enter the cell efficiency as a function of direct normal irradiance (DNI) in the plane of the module surface, but it also shows you the equivalent sun concentration calculated from the concentration ratio you provide at the top of the input page.

If your data sheet shows efficiency as a function of concentration, you can convert the values to DNI using the following equation:

DNI (W/m2) = Concentration (suns) / Concentration Ratio * 1000 (W/m2/sun)

Best regards,
Paul.

Princess_Zaynab
Princess_Zaynab's picture

Dear Paul,
Thank's a lot for your answer.
Can you please send me back the relation between DNI and concentration(suns) with more parenthesis because I don't know if I should divide or multiply by 1000?

Thank's a lot in advance,
Zaynab

Paul Gilman

Dear Zaynab,

Here is an example:

Concentration ratio = 700 X
Concentration = 630 Suns
1 Sun = 1000 W/m2

DNI = 630 / 700 * 1000 = 900 W/m2

Best regards,
Paul.

Princess_Zaynab
Princess_Zaynab's picture

Thank's a lot !

saeedra0

Dear paul
Is "sun concentration" and "concentration(suns)" same or not?
For example i want enter efficiency for concentration=960suns,DNI=600W/m2,concentration ratio=1600 but the Data sheet has the efficiency as a function of sun concentration in standard condition of 1000W/m2.
Is it OK to use the efficiency of sun concentration=960 in standard condition of 1000W/m2.

Paul Gilman

Hello,

The concentration in Suns is another way of describing the irradiance in W/m2 given a concentration ratio. You can use the equation I provided above to convert between the two.

Best regards,
Paul.

saeedra0

Dear paul

Yes i know that but the data sheet has gave the efficiency of sun concentration in 1000 W/m2 not for example in 900 W/m2.

If you send me an email i can send u the data sheet to see what i mean.

I have another question too,what number should i put as packing factor in hcpv what's the difference with GCR in PV system?

thank you
saeed

Paul Gilman

Dear Saeed,

If the datasheet only has the efficiency at one point on the curve, you may need to estimate the efficiency at different irradiances, or you could use a flat curve by using the same efficiency value for all of the irradiance levels.

The packing factor input on the Array page is described in the Help topic for that page. It is a way to account for the cost of land as a function of module area. It is different from the GCR for the PV model, which is used for self-shading calculations. The HCPV model assumes that the trackers are spaced so that there is no self shading.

You can use the Contact page to email me.

Best regards,
Paul.

saeedra0

thank you

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