Unified methodology for determining CTM ratios: Systematic prediction of module power

Haedrich, Ingrid; Eitner, Ulrich; Wiese, Martin; Wirth, Harry

doi:10.1016/j.solmat.2014.06.025

Cited by 85 publications

(41 citation statements)

References 15 publications

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“…Table 1 shows the typical performance of the half-cell and full-cell modules with different cell efficiency. It can be found that the CTM power ratio of half-cell module is over 100%, which indicates that the optical gain from cells to module is higher than the optical and electrical loss [3,5]. The CTM of the half-cell module with 18.2% cell efficiency is 2.83% higher than the full-cell module with 2.6% improvement in FF.…”

Section: Resultsmentioning

confidence: 95%

“…To further decrease the cost of PV electricity, the solar cell and module efficiency must be further improved and the cost of manufacturing should be reduced [1]. When solar cells are transferred into a module, series resistance arising from the cell interconnection and optical losses caused by the encapsulation may bring additional losses to the module output power, which is often evaluated by the cell to module power ratio (CTM) [2,3].…”

Section: Introductionmentioning

confidence: 99%

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Study on the Benefit of Half-Cut Cells towards Higher Cell-to-Module Power Ratio

Zhang¹,

Zhuang²,

Gou³

et al. 2018

dteees

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Abstract. Half-cut cell technology has been proposed as an effective way to largely decrease the cell to module loss by decreasing the current level in the cell string. The type of laser is strongly correlated with the quality of the cut cells and further performance of the half-cell based modules. We investigated the effect of laser on the quality and performance of half-cut cells. And different types of half-cut cells were made into modules, the cell-to-module power ratio of which was evaluated and compared with full-size cells. Electroluminescence was employed to characterize the quality of the cut cells as well as the half-cell modules. Our results demonstrate that an approximately 2.2% average extra power gain can be obtained using half-cut cells for module encapsulation.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Study on the Benefit of Half-Cut Cells towards Higher Cell-to-Module Power Ratio

Zhang¹,

Zhuang²,

Gou³

et al. 2018

dteees

View full text Add to dashboard Cite

show abstract

“…31,65,66 There is also promising work to reduce cell-to-module losses. [67][68][69] The price constraint on installed capacity depends strongly on the demand curve for PV. The demand curve in turn depends on a multitude of factors unrelated to PV module technology.8 To capture the uncertainty in these factors over a period of decades, we shift the demand curve to simulate increased and decreased demand at a given PV module price (see ESI † for details) and recalculate installations over time for each of our technology scenarios.…”

Section: View Article Onlinementioning

confidence: 99%

Economically sustainable scaling of photovoltaics to meet climate targets

Needleman

Poindexter

Kurchin

et al. 2016

Energy Environ. Sci.

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aTo meet climate targets, power generation capacity from photovoltaics (PV) in 2030 will have to be much greater than is predicted from either steady state growth using today's manufacturing capacity or industry roadmaps. Analysis of whether current technology can scale, in an economically sustainable way, to sufficient levels to meet these targets has not yet been undertaken, nor have tools to perform this analysis been presented. Here, we use bottom-up cost modeling to predict cumulative capacity as a function of technological and economic variables. We find that today's technology falls short in two ways: profits are too small relative to upfront factory costs to grow manufacturing capacity rapidly enough to meet climate targets, and costs are too high to generate enough demand to meet climate targets. We show that decreasing the capital intensity (capex) of PV manufacturing to increase manufacturing capacity and effectively reducing cost (e.g., through higher efficiency) to increase demand are the most effective and least risky ways to address these barriers to scale. We also assess the effects of variations in demand due to hard-to-predict factors, like public policy, on the necessary reductions in cost. Finally, we review examples of redundant technology pathways for crystalline silicon PV to achieve the necessary innovations in capex, performance, and price. Broader contextTo reduce CO 2 emissions enough over the next fifteen years and avoid the worst effects of climate change will require dramatic increases in the deployment of renewable energy, photovoltaics (PV) in particular. Climate action plans call for 2-10 terawatts (TW) of PV by 2030. Current manufacturing capacity could supply enough for 1 TW of cumulative installations at the end of this period, implying that growth in manufacturing capacity is necessary. Industry roadmaps project up to 2.6 TW but largely fail to assess whether these targets are economically feasible with today's PV module technology. Addressing the question of what technological innovations, if any, would enable rapid manufacturing scale-up requires a conceptual advance in modeling methodology. We address this challenge by coupling three industry-validated models: a bottom-up cost model, an economically sustainable growth-rate calculator, and a constraining demand curve. This approach enables us to determine the sensitivity of PV industry growth to specific technological and economic variables, considering both their effect on the ratio of up-front factory costs to revenue and demand as a function of PV module price. Shifting the demand curve enables us to consider the effects of different policy decisions, like a carbon tax or deployment subsidies.

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“…Secondly, cell‐to‐module (CTM) changes in performance need to be accounted for. We follow the approach described in Reference . The following contributions to CTM changes are assumed, and their impact in terms of relative change in output power is assigned to factors f i : (i) optics loss, which includes reflection at the glass and the glass/EVA (ethylene‐vinyl acetate) interface as well as parasitic absorption in the glass and EVA and additional shading because of cell interconnectors, (ii) optics gain ‘ARC + metal’, which includes better optical coupling because of the better refractive index match of the EVA to the SiN‐ARC compared with the direct coupling to air and for the better coupling of re‐reflected light impinging on metallisation fingers and cell interconnector and (iii) optics gain ‘BS’ due to coupling from a white backsheet.…”

Section: Economicsmentioning

confidence: 99%

Economic feasibility of bifacial silicon solar cells

Fertig

Nold

Wöhrle

et al. 2016

Progress in Photovoltaics

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Bifacial solar cells and modules are a promising approach to increase the energy output of photovoltaic systems, and therefore decrease levelized cost of electricity (LCOE). This work discusses the bifacial silicon solar cell concepts PERT (passivated emitter, rear totally diffused) and BOSCO (both sides collecting and contacted) in terms of expected module cost and LCOE based on in-depth numerical device simulation and advanced cost modelling. As references, Al-BSF (aluminium back-surface field) and PERC (passivated emitter and rear) cells with local rear-side contacts are considered. In order to exploit their bifacial potential, PERT structures (representing cells with single-sided emitter) are shown to require bulk diffusion lengths of more than three times the cell thickness. For the BOSCO concept (representing cells with double-sided emitter), diffusion lengths of half the cell thickness are sufficient to leverage its bifacial potential. In terms of nominal LCOE, BOSCO cells are shown to be cost-competitive under monofacial operation compared with an 18% efficient (≙ pMPP = 18 mW/cm2) multicrystalline silicon (mc-Si) Al-BSF cell and a 19% mc-Si PERC cell for maximum output power densities of pMPP ≥ 17.3 mW/cm2 and pMPP ≥ 18.1 mW/cm2, respectively. These values assume the use of $10/kg silicon feedstock for the BOSCO and $20/kg for the Al-BSF and PERC cells. For the PERT cell, corresponding values are pMPP ≥ 21.7 mW/cm2 and pMPP ≥ 22.7 mW/cm2, respectively, assuming the current price offset (≈50%, at the time of October 2014) of n-type Czochralski-grown silicon (Cz-Si) compared with mc-Si wafers. The material price offset of n-type to p-type Cz-Si wafers (≈15%, October 2014) currently accounts for approximately 1 mW/cm2, which correlates to a conversion efficiency difference of 1%abs for monofacial illumination with 1 sun. From p-type mc-Si to p-type Cz-Si (≈30% wafer price offset, October 2014), this offset is approximately 2.5 mW/cm2 for a PERT cell. When utilizing bifacial operation, these required maximum output power densities can be transformed into required minimum rear-side illumination intensities for arbitrary front-side efficiencies ηfront by means of the performed numerical simulations. For a BOSCO cell with ηfront = 18%, minimum rear-side illumination intensities of ≤ 0.02 suns are required to match a 19% PERC cell in terms of nominal LCOE. For an n-type Cz-Si PERT cell with ηfront = 21%, corresponding values are ≤ 0.11 suns with 0.05 suns being the n-type to p-type material price offset. This work strongly motivates the use of bifacial concepts to generate lowest LCOE

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Unified methodology for determining CTM ratios: Systematic prediction of module power

Cited by 85 publications

References 15 publications

Study on the Benefit of Half-Cut Cells towards Higher Cell-to-Module Power Ratio

Study on the Benefit of Half-Cut Cells towards Higher Cell-to-Module Power Ratio

Economically sustainable scaling of photovoltaics to meet climate targets

Economic feasibility of bifacial silicon solar cells

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