468 lines
26 KiB
TeX
468 lines
26 KiB
TeX
\documentclass[final,1p,times,nonatbib]{elsarticle}
|
|
\usepackage{amssymb,amsmath,booktabs}
|
|
\usepackage{tikz}
|
|
\usetikzlibrary{positioning,arrows.meta}
|
|
\usepackage[backend=biber,style=numeric,sorting=none]{biblatex}
|
|
\addbibresource{cas-refs.bib}
|
|
\setlength{\emergencystretch}{1em}
|
|
\input{metrics_2026_11_04}
|
|
|
|
\begin{document}
|
|
\begin{frontmatter}
|
|
\title{Outdoor Characterization of Photocurrent-Based Focal Tracking in a Tracking-Integrated Micro-Concentrator Photovoltaic System}
|
|
|
|
\author[inst1]{Fernando Dávalos Hernández\corref{cor1}}
|
|
\author[inst2,inst3]{Arturo Díaz-Ponce}
|
|
\author[inst3]{Iván Trejo-Zúñiga}
|
|
\author[inst4]{Rosa C. Anguiano Cota}
|
|
\author[inst1]{Pedro M. Rodrigo}
|
|
\author[inst5]{María A. Ceballos}
|
|
\author[inst5]{Álvaro Valera-Albacete}
|
|
\author[inst5]{Florencia Almonacid}
|
|
\author[inst5]{Eduardo F. Fernández}
|
|
|
|
\affiliation[inst1]{organization={Universidad Panamericana, Facultad de Ingeniería},
|
|
addressline={Jose María Escrivá de Balaguer 101, Villas Bonaterra},city={Aguascalientes},
|
|
postcode={20296},state={Aguascalientes},country={Mexico}}
|
|
\affiliation[inst2]{organization={SECIHTI -- Centro de Investigaciones en Óptica, A.C., Unidad Aguascalientes},
|
|
addressline={Prol. Constitución 607, Fracc. Reserva Loma Bonita},city={Aguascalientes},
|
|
postcode={20200},state={Aguascalientes},country={Mexico}}
|
|
\affiliation[inst3]{organization={Laboratory of Energy Innovation and Intelligent and Sustainable Agriculture (LEIISA), Universidad Tecnológica de San Juan del Río},
|
|
addressline={Av La Palma No 125 Vista Hermosa},city={San Juan del Río},postcode={76800},
|
|
state={Querétaro},country={Mexico}}
|
|
\affiliation[inst4]{organization={Facultad de Ingeniería, Universidad Autónoma de Baja California (UABC)},
|
|
addressline={Blvd. Benito Juárez SN},city={Mexicali},postcode={21280},
|
|
state={Baja California},country={Mexico}}
|
|
\affiliation[inst5]{organization={Advances in Photovoltaic Technology (AdPVTech), CEACTEMA, University of Jaén},
|
|
addressline={Las Lagunillas Campus},city={Jaén},postcode={23071},state={Jaén},country={Spain}}
|
|
\cortext[cor1]{Corresponding author. Email: fdavalos@up.edu.mx}
|
|
|
|
\begin{abstract}
|
|
Tracking-integrated concentrator photovoltaics preserve fixed external optics
|
|
while moving the receiver to follow the evolving focal region. Their field
|
|
performance therefore depends on both optical collection and internal
|
|
positioning, rather than on external solar pointing alone. This work
|
|
characterizes a photocurrent-feedback controller and custom ESP32 acquisition
|
|
system for a wide-acceptance-angle tracking-integrated micro-concentrator
|
|
photovoltaic (WiT-CPV) prototype. The principal experiment is the 4 November
|
|
2026 outdoor record in Aguascalientes, Mexico: \NovSamples{} observations
|
|
between 09:52 and 16:05, with \NovHours{} h of accepted integration support
|
|
and no ADC clipping. Sequential short-circuit-current and open-circuit-voltage
|
|
measurements yield an estimated available maximum-power-point energy of
|
|
\NovEnergy{} Wh for an assumed fill factor of 0.82. Relative to the
|
|
0.002497-m$^2$ lens aperture and the coplanar pyranometric irradiation of
|
|
\NovIrradiation{} kWh\,m$^{-2}$, the energy-weighted efficiency estimate is
|
|
\NovEfficiency\%. The command-delimited 12:32--13:53 post-tuning phase yields
|
|
an aperture estimate of \NovSteadyEfficiency\% without additional logged
|
|
operator commands. Solar-position data contextualize the operating trajectory,
|
|
while the complete record retains tuning interventions and late response
|
|
degradation. Reference sensitivity is examined rather than treated as an
|
|
independent tracking-accuracy measurement. An equal-aperture silicon comparison
|
|
is reported as a conditional constant-efficiency scenario, not a simultaneous
|
|
panel experiment. The results establish an aperture-referenced field
|
|
characterization and identify the measurements needed to validate delivered
|
|
power, net energy and angular tracking accuracy.
|
|
\end{abstract}
|
|
|
|
\begin{highlights}
|
|
\item A \NovSamples{}-sample field record characterizes internal focal tracking
|
|
\item Estimated aperture efficiency is \NovEfficiency\% over \NovHours{} h of accepted support
|
|
\item A post-tuning phase yields a \NovSteadyEfficiency\% aperture estimate
|
|
\item Solar-position context and late response losses define observed operation
|
|
\item Fixed-silicon scenarios use equal aperture and explicitly stated assumptions
|
|
\end{highlights}
|
|
|
|
\begin{keyword}
|
|
Tracking-integrated CPV \sep Focal tracking \sep Photocurrent feedback \sep
|
|
Aperture efficiency \sep Outdoor characterization \sep Silicon photovoltaic benchmark
|
|
\end{keyword}
|
|
\end{frontmatter}
|
|
|
|
\section{Introduction}
|
|
\label{sec:introduction}
|
|
|
|
Photovoltaic energy collection depends on the relationship between solar
|
|
direction, collector orientation and device response. Conventional
|
|
one- and two-axis trackers improve this relationship by moving the module
|
|
or concentrator as a whole, at the cost of actuation, support and control
|
|
requirements \cite{mousazadeh2009review,hafez2018solar,fuentes2020control}.
|
|
In concentrating photovoltaics (CPV), optical alignment is especially
|
|
important because displacement of the focal distribution can reduce the
|
|
fraction intercepted by a small receiver \cite{iqbal2023optical}.
|
|
|
|
Tracking-integrated CPV transfers part or all of the required motion inside
|
|
the module \cite{ceballos2023tracking}. Microtracking lens arrays, internally
|
|
translated receivers and hybrid diffuse-light collection illustrate different
|
|
ways of decoupling focal alignment from large external motion
|
|
\cite{ito2018optical,askins2019performance,younes2022realizing}.
|
|
This distinction matters when interpreting field performance: moving a
|
|
receiver beneath fixed optics does not make the optical aperture normal to
|
|
the Sun, nor does it eliminate the finite angular and mechanical operating
|
|
range of the assembly.
|
|
|
|
The wide-acceptance-angle tracking-integrated micro-concentrator photovoltaic
|
|
(WiT-CPV) prototype studied here was previously reported with its optical and
|
|
mechanical design, azimuthal cell rotation and first-generation controller
|
|
\cite{diasponce2025development}. Its receiver follows the moving focal region
|
|
of a biconvex aspheric lens along a mechanically constrained trajectory.
|
|
Knowledge of solar position alone does not establish the corresponding
|
|
receiver coordinates: optical geometry, mounting and kinematics must also
|
|
be known. Photocurrent provides a useful local feedback signal, although
|
|
irradiance, temperature and spectrum can change it independently of alignment.
|
|
|
|
The present contribution is a field characterization of this coupled system
|
|
using the complete acquired record of 4 November 2026. It connects measured
|
|
electrical signals and stage coordinates to an explicitly estimated
|
|
aperture-level output, places the response in solar-position context, and
|
|
discloses data gaps and operational interventions. A fixed-silicon scenario
|
|
provides an area-normalized engineering reference without substituting a
|
|
simulation for an unperformed experiment. This focus replaces comparisons
|
|
between heterogeneous development sessions with a traceable principal case;
|
|
it does not constitute a controlled comparison of controller versions or
|
|
a validation of net energy production.
|
|
|
|
\section{System and Control}
|
|
\label{sec:system}
|
|
|
|
\subsection{Optical and mechanical architecture}
|
|
|
|
The prototype combines fixed primary optics, a multi-junction photovoltaic
|
|
receiver and a two-axis actuated stage. Guided mechanical motion follows
|
|
the curved focal trajectory associated with the Petzval surface; the detailed
|
|
optomechanical construction is described in \cite{diasponce2025development}.
|
|
The lens aperture used in the present analysis is
|
|
$A_L=0.002497$~m$^2$. Coordinates $X$ and $Y$ denote the project's azimuth
|
|
and elevation axes, respectively. They are commanded step coordinates,
|
|
not independently measured solar or receiver angles. The acquisition does
|
|
not provide a calibrated steps-to-angle transformation or an independent
|
|
measurement of focal-position error.
|
|
|
|
\subsection{Controller and measurement chain}
|
|
|
|
An ESP32-based controller provides wireless command/telemetry interfaces
|
|
and commands two TMC2209 stepper drivers. A 24-bit ADS122C04 converter
|
|
acquires the photocurrent, pyranometer and cell-voltage channels. The
|
|
photocurrent chain uses a nominal 0.130-$\Omega$ shunt for the evaluated
|
|
PCB V2 configuration, an external gain of 20 and a 2.048-V reference.
|
|
Open-circuit voltage is acquired through a factor-of-two divider, and an
|
|
Apogee SP-212 provides the irradiance reference. The functional measurement
|
|
and control paths are summarized in Fig.~\ref{fig:architecture}.
|
|
|
|
\begin{figure}[htbp]
|
|
\centering
|
|
\begin{tikzpicture}[>=Latex,font=\small,
|
|
box/.style={draw,rounded corners=2pt,align=center,minimum height=11mm,text width=40mm},
|
|
node distance=11mm and 20mm]
|
|
\node[box] (optics) {Fixed primary lens\\$A_L=0.002497$ m$^2$};
|
|
\node[box,right=of optics] (cell) {Moving receiver\\$X$: azimuth; $Y$: elevation};
|
|
\node[box,below=of cell] (adc) {Sequential ADC acquisition\\$I_{sc}$, $G$, $V_{oc}$};
|
|
\node[box,left=of adc] (control) {ESP32 and motor drivers\\Photocurrent feedback};
|
|
\node[box,below=of adc] (analysis) {Logged observations\\Offline calibration\\and analysis};
|
|
\draw[->] (optics) -- node[above]{Focal region} (cell);
|
|
\draw[->] (cell) -- (adc);
|
|
\draw[->] (adc) -- node[above]{$C$ feedback} (control);
|
|
\draw[->] (control.west) -- ++(-7mm,0) |- ([yshift=8mm]cell.north) -- (cell.north);
|
|
\node[above=8mm of cell,font=\scriptsize] {Internal motion};
|
|
\draw[->] (adc) -- (analysis);
|
|
\end{tikzpicture}
|
|
\caption{Functional architecture of the evaluated system. Only the receiver
|
|
is repositioned; internal tracking does not reorient the external aperture.
|
|
Electrical channels are acquired sequentially, and the offline power estimate
|
|
is not feedback from a measured MPP load.}
|
|
\label{fig:architecture}
|
|
\end{figure}
|
|
|
|
The cell is switched between short-circuit-current and open-circuit-voltage
|
|
measurement states. Current, irradiance and voltage therefore represent
|
|
sequential conversions rather than a simultaneous electrical operating
|
|
point. The periodic \texttt{TEL} messages contain separate telemetry averages
|
|
and fine-tuning counters; they are not interchangeable with the coordinate/
|
|
electrical observations used for the quantitative analysis.
|
|
|
|
\subsection{Evaluated control and implementation provenance}
|
|
\label{sec:control_provenance}
|
|
|
|
The raw record identifies the deployed firmware as \texttt{1.1.3-ws}.
|
|
The controller performs photocurrent-feedback fine tuning, with configurable
|
|
step bounds, current-change thresholds, peak-proximity settings and
|
|
axis-search cycles. Its log reports adaptive-step diagnostics and periodic
|
|
reference resets. Pyranometer input supports illumination-related operating
|
|
logic, but the offline $I_{sc}/G$ ratio used below must not be interpreted
|
|
as a verified samplewise feedback law of the evaluated firmware.
|
|
|
|
The available development source has subsequently changed; in particular,
|
|
later revisions address current-change, near-peak and deadband behavior.
|
|
Those later equations and features are not attributed to the recorded
|
|
deployment. Accordingly, this article describes the evaluated controller at
|
|
the level supported by version identifiers and logged behavior, rather than
|
|
presenting unverified branch equations as an exact specification of its binary.
|
|
The experiment includes parameter updates and manual positioning commands.
|
|
It is an operational field characterization with disclosed tuning, not a
|
|
fixed-parameter autonomous trial, an ablation study or proof that each
|
|
protective control regime operates as intended.
|
|
|
|
\section{Experimental and Analytical Methods}
|
|
\label{sec:methods}
|
|
|
|
\subsection{Site, acquisition and solar-position reference}
|
|
|
|
The principal acquisition took place on 4 November 2026 in Aguascalientes,
|
|
Mexico. The supplied SunCalc printout identifies latitude
|
|
$21.87304^\circ$ N and longitude $102.28282^\circ$ W and tabulates solar
|
|
azimuth and elevation at 15-min intervals \cite{suncalc2026}.
|
|
The field conditions were described as clear by the experimenter; this is
|
|
a field observation, not an independently measured classification of direct
|
|
and diffuse irradiance. Brief irradiance anomalies are retained and examined.
|
|
|
|
Time plots use the local acquisition clock. The log has no encoded time-zone
|
|
offset, so matching to the supplied local-time SunCalc table is an explicit
|
|
clock-alignment assumption, not an independent timing calibration.
|
|
Linear interpolation between the printed solar positions supplies context
|
|
at observation times. It does not improve the ephemeris resolution or measure
|
|
stage accuracy. Azimuth is measured clockwise from north and elevation above
|
|
the horizon. Neither absolute solar azimuth nor its span equals the collector
|
|
incidence angle. The acquisition package does not establish absolute external-optics
|
|
tilt/azimuth, so conversion to a validated
|
|
optical acceptance envelope is not attempted.
|
|
|
|
\subsection{Offline calibration and data-quality rules}
|
|
|
|
Let $C$, $V$ and $P$ denote the signed 24-bit photocurrent, voltage and
|
|
pyranometer codes, with positive full scale $D=8{,}388{,}607$. Offline conversion is
|
|
\begin{align}
|
|
I_{sc}&=\frac{2.048 C}{20D R_s}, &
|
|
V_{oc}&=\frac{2(2.048)V}{D}, &
|
|
G&=\frac{2048P}{0.2D},\quad R_s=0.130~\Omega.
|
|
\label{eq:calibration}
|
|
\end{align}
|
|
The resulting units are A, V and W\,m$^{-2}$. The pyranometer sensitivity
|
|
is 0.2~mV/(W\,m$^{-2}$); using 2.0 would understate irradiance tenfold.
|
|
The raw channels are not exchanged: \texttt{C} is photocurrent and
|
|
\texttt{P} is pyranometer output. The same physical shunt applies throughout
|
|
this record; a software conversion update at the hub does not define a
|
|
physical shunt change in the raw acquisition.
|
|
|
|
The experimenter confirms that the SP-212 was mounted in the same plane as
|
|
the concentration lens. Thus $G$ is measured global irradiance in the fixed
|
|
lens-aperture plane, and $G A_L$ estimates incident solar power on that
|
|
aperture. No additional cosine projection is applied: the beam's geometric
|
|
projection onto the receiving plane is already represented in the coplanar
|
|
irradiance measurement. This quantity is not direct-normal irradiance.
|
|
The SP-212's spectral and angular responses differ from those of concentrating
|
|
multi-junction optics \cite{apogee_sp212_manual}; its calibration and angular
|
|
response, and the concentrator's limited collection of diffuse light, remain
|
|
relevant to the uncertainty and interpretation.
|
|
Offline scaling also does not retroactively correct firmware irradiance
|
|
thresholds or change historical control decisions.
|
|
No experiment-specific uncertainty budget is available for shunt resistance,
|
|
amplifier gain, voltage reference or irradiance calibration. Reported decimal
|
|
places identify reproducible calculations, not a demonstrated metrological
|
|
precision or confidence interval.
|
|
|
|
Every observation retains its source line, raw codes and quality flags.
|
|
Checks include signed conversion, channel clipping, a 99\%-of-current-rail
|
|
guard, negative channels, timestamps and uptime discontinuities. For integration,
|
|
both adjacent endpoints must be electrically accepted and illuminated
|
|
($G>50$~W\,m$^{-2}$), their separation must be positive and at most 15~s,
|
|
and uptime must not decrease. Rejected observations and long gaps are never
|
|
bridged. Low output and manual interventions are retained, not excluded
|
|
because they reduce a performance score. Clock-hour subdivisions are
|
|
descriptive and accompany, rather than replace, the complete acquired record.
|
|
|
|
\subsection{Estimated output and aperture-referenced performance}
|
|
|
|
The instantaneous available-MPP proxy and its energy integral are
|
|
\begin{equation}
|
|
\widehat P_{\mathrm{MPP}}=I_{sc}V_{oc}FF,\qquad
|
|
\widehat E=\int_{\mathcal S}\widehat P_{\mathrm{MPP}}\,dt,
|
|
\qquad FF=0.82,
|
|
\label{eq:power_estimate}
|
|
\end{equation}
|
|
where $\mathcal S$ is the union of accepted adjacent intervals and time is
|
|
expressed in hours for Wh. A fixed fill factor is assumed; no outdoor I--V
|
|
curve, MPP converter or delivered-load power is inferred. Sequential sensing
|
|
further assumes approximately stable conditions across the conversion cycle,
|
|
which can fail during rapid changes. Thus $\widehat E$ estimates available
|
|
electrical energy, not harvested or net system energy.
|
|
|
|
On the identical temporal support, define
|
|
\begin{equation}
|
|
H=\int_{\mathcal S}G\,dt,\qquad
|
|
\widehat\eta_{\mathrm{ap},E}=\frac{\widehat E}{A_L H},\qquad
|
|
\widehat\eta_{\mathrm{ap}}(t)=\frac{\widehat P_{\mathrm{MPP}}(t)}{A_LG(t)}.
|
|
\label{eq:aperture}
|
|
\end{equation}
|
|
The integrated ratio, reported as a percentage, is not the mean of the
|
|
instantaneous ratios. With the confirmed coplanar irradiance measurement,
|
|
it estimates the complete lens/receiver combination's electrical conversion
|
|
relative to solar energy incident on its aperture, not intrinsic cell efficiency.
|
|
Optical losses that reduce the measured cell response are already reflected
|
|
in the numerator; no additional lens-transmission factor is applied to that output.
|
|
For any alternative constant $FF'$, $\widehat E$ and
|
|
$\widehat\eta_{\mathrm{ap},E}$ scale by $FF'/0.82$; this is sensitivity
|
|
to an assumption, not a calibrated uncertainty interval.
|
|
|
|
\subsection{Relative response without an ideal-alignment claim}
|
|
|
|
To describe electrical response relative to a common empirical reference,
|
|
let $R(t)=I_{sc}(t)/G(t)$ and consider both its full-record maximum
|
|
$R_{\max}$ and 99th percentile $R_{99}$. For either reference $R_*$,
|
|
\begin{equation}
|
|
\widehat P_{\mathrm{ref}}(t;R_*)=R_*G(t)V_{oc}(t)FF,\qquad
|
|
\rho_E(R_*)=\frac{\int_{\mathcal S}\widehat P_{\mathrm{MPP}}dt}
|
|
{\int_{\mathcal S}\widehat P_{\mathrm{ref}}(t;R_*)dt}.
|
|
\label{eq:relative_yield}
|
|
\end{equation}
|
|
This is a record-specific relative-yield indicator, not independently
|
|
validated tracking efficiency or angular accuracy. Neither reference removes
|
|
temperature, spectral, geometry or asynchronous-sensing effects. The P99
|
|
reference is not a strict ceiling; ratios are not clipped to 100\%.
|
|
Sensitivity to reference choice is part of the result, not a reason to select
|
|
the reference that produces the most favorable number.
|
|
|
|
\subsection{Equal-area fixed-silicon reference scenario}
|
|
\label{sec:silicon_methods}
|
|
|
|
No simultaneous silicon reference measurement accompanies the acquisition.
|
|
We therefore define a conditional equal-area scenario for a hypothetical fixed
|
|
silicon surface coplanar with the lens, using the measured plane-of-aperture
|
|
irradiance and the accepted temporal support of the CPV estimate:
|
|
\begin{equation}
|
|
P_{\mathrm{Si,scenario}}(t)=A_L\eta_{\mathrm{Si}}G(t),\qquad
|
|
E_{\mathrm{Si,scenario}}=A_L\eta_{\mathrm{Si}}H,\qquad
|
|
B=\frac{\widehat E}{E_{\mathrm{Si,scenario}}}.
|
|
\label{eq:silicon_scenario}
|
|
\end{equation}
|
|
PVWatts lists approximate nominal module efficiencies of 19\% and 21\%
|
|
for its Standard and Premium crystalline-silicon categories, respectively
|
|
\cite{pvwatts_module_type}. These two assumptions provide model-based context,
|
|
not upper/lower bounds on silicon technology or specifications of a tested
|
|
panel. The equivalent area is a normalization, not a fabricated 0.002497-m$^2$
|
|
module. This scenario does not assume equal rated power or equal cell area.
|
|
Since $B=\widehat\eta_{\mathrm{ap},E}/\eta_{\mathrm{Si}}$ under these
|
|
assumptions, the comparison is an algebraic restatement of the aperture
|
|
estimate, not independent experimental evidence.
|
|
|
|
Holding silicon efficiency constant isolates the area/irradiation comparison;
|
|
it does not predict temperature-corrected field yield. A physical module model
|
|
would additionally require module-specific optical corrections to the measured
|
|
plane irradiance, cell temperature and thermal mounting conditions
|
|
\cite{sandia_poa,sandia_pvwatts}. PVWatts' corresponding nominal
|
|
power-temperature coefficients are $-0.37$ and $-0.35$\%/K, but no unmeasured
|
|
silicon temperature is assigned here. Coplanarity supports the common incident
|
|
irradiance basis, but does not equate absorbed effective irradiance or measured
|
|
electrical output for the two technologies. Values of $B$ are conditional
|
|
arithmetic comparisons, not measured energy gains over silicon.
|
|
|
|
\section{Field Results}
|
|
\label{sec:results}
|
|
\input{results_2026_11_04}
|
|
|
|
\section{Discussion}
|
|
\label{sec:discussion}
|
|
|
|
\subsection{What the principal experiment establishes}
|
|
|
|
The principal result is a single, traceable operating characterization that
|
|
connects internal motion, electrical response and solar-position context.
|
|
The unsaturated current channel permits analysis of the acquired daytime
|
|
span without reconstructing clipped high-current observations. The
|
|
\NovEfficiency\% integrated aperture estimate retains initialization,
|
|
tuning and degraded response; it is therefore more informative about this
|
|
record than a favorable midday peak alone. The useful output during changing
|
|
solar direction supports the feasibility of internal receiver tracking,
|
|
but does not isolate the controller's contribution from manual intervention
|
|
or establish an ideal focal trajectory.
|
|
|
|
The lower late response is part of the demonstrated behavior, not a discarded
|
|
outlier. Finite travel, optical acceptance, alignment, temperature and
|
|
control settings could all contribute. Solar ephemerides and commanded
|
|
coordinates alone cannot separate them. Establishing an angular operating
|
|
envelope requires known external-optics orientation and an independent
|
|
mapping between receiver position, incidence angle and optical response.
|
|
|
|
\subsection{Why relative tracking and aperture efficiency differ}
|
|
|
|
The aperture metric compares estimated electrical output with measured
|
|
reference irradiation; the relative-yield metric instead compares against
|
|
a same-record electrical responsivity. They answer different questions.
|
|
An anomalously low irradiance reading can inflate both instantaneous aperture
|
|
efficiency and a maximum-responsivity reference while depressing the
|
|
maximum-referenced full-record ratio. A stable-looking current trace does
|
|
not resolve whether a brief discrepancy arose from weather, sensor shading,
|
|
electrical acquisition or different sensor/device response.
|
|
|
|
Consequently, the reference sensitivity must not be compressed into one
|
|
unqualified tracking-efficiency headline. Even a robust percentile reference
|
|
remains empirical, reuses the measured voltage and cannot independently
|
|
measure perfect alignment. Irradiance normalization also cannot distinguish
|
|
thermal drift from small alignment-induced changes. The record does not
|
|
validate cloud-recovery time or the causal benefit of a specific protective
|
|
branch; those require controlled perturbations or independently characterized
|
|
disturbances.
|
|
|
|
\subsection{Interpreting the silicon comparison and next validation}
|
|
|
|
The shared-reference scenario places the aperture estimate alongside
|
|
transparent nominal silicon-efficiency assumptions, without treating the
|
|
CPV aperture as externally tracked at normal incidence. Its dependencies are
|
|
the assumed fill factor and silicon efficiency, together with unmeasured
|
|
temperature and module-specific optical response. The confirmed coplanar sensor
|
|
provides the incident-irradiance basis for the equal-plane scenario. Different diffuse,
|
|
spectral and angular responses prevent extrapolating the scenario to annual
|
|
yield or arbitrary weather. No economic or lifecycle advantage is inferred.
|
|
|
|
A simultaneous experiment should measure silicon DC output at MPP, document
|
|
module area and datasheet parameters, and record tilt, azimuth, coplanar
|
|
irradiance and module temperature. Equivalent delivered-energy claims also
|
|
require CPV operation into a measured load rather than alternating
|
|
$I_{sc}/V_{oc}$ sensing. For net energy, the complete board and motor supply
|
|
must be logged. Fine-tuning counters omit other moves, and sampled coordinate
|
|
differences can miss reversals; neither substitutes for supply-energy
|
|
measurement. The most useful next campaign therefore combines those
|
|
measurements with fixed documented settings and repeated days, followed by
|
|
controlled controller-version comparisons.
|
|
|
|
\section{Conclusions}
|
|
\label{sec:conclusions}
|
|
|
|
The 4 November 2026 acquisition provides a coherent principal field case for
|
|
the tracking-integrated WiT-CPV prototype: \NovSamples{} observations,
|
|
\NovHours{} h of accepted integration support, and no ADC clipping. With
|
|
a nominal 0.130-$\Omega$ shunt, corrected pyranometer scaling and an assumed
|
|
$FF=0.82$, the available-MPP energy estimate is \NovEnergy{} Wh for
|
|
\NovIrradiation{} kWh\,m$^{-2}$ of reference irradiation. The resulting
|
|
energy-weighted, aperture-referenced estimate is \NovEfficiency\%.
|
|
These quantities characterize the lens/receiver system against the recorded
|
|
irradiance, rather than intrinsic cell efficiency or measured harvested energy.
|
|
|
|
Linking the response to the solar-position reference and stage trajectory
|
|
reveals useful operation as well as late degradation. The event-defined
|
|
12:32--13:53 phase has no additional logged remote commands and yields an
|
|
aperture estimate of \NovSteadyEfficiency\%, providing a post-tuning operating
|
|
case alongside the complete-record result. Retaining tuning
|
|
commands and low-output periods makes the result a characterization of
|
|
observed operation, not a claim of autonomous full-day lock. A pronounced
|
|
irradiance anomaly also demonstrates why a same-record maximum cannot be
|
|
treated as an independently validated ideal-tracking reference.
|
|
|
|
Under the shared-pyranometer, constant-efficiency assumptions, the estimated
|
|
CPV energy corresponds to ratios of \NovSiliconStandardRatio{} and
|
|
\NovSiliconPremiumRatio{} relative to the 19\% and 21\% equal-area silicon
|
|
scenarios. These are arithmetic scenario ratios, not measured comparative
|
|
yields or evidence of superiority over a fixed panel. The decisive next validation is
|
|
simultaneous delivered-MPP and parasitic-power measurement, with matched receiving
|
|
planes, measured temperature and fixed control settings. This would turn the present
|
|
aperture-level characterization into a test of repeatable net system benefit.
|
|
|
|
\section*{Reproducibility}
|
|
The companion analysis retains the raw observations, source-line references,
|
|
quality flags, accepted integration edges and command chronology. Its
|
|
machine-readable summary records source hashes and assumptions; the supplied
|
|
SunCalc table is transcribed separately. Numerical tests cover calibration,
|
|
gap handling, integration and scenario scaling. All result tables and field
|
|
figures are regenerated from these inputs, without modifying the raw log.
|
|
|
|
\printbibliography
|
|
\end{document}
|