Mobile vertical photovoltaic system

Przemysław Andrzej Stobiecki

doi:10.37190/arc250414

Abstract

The author’s objective was to present an original alternative technical solution enabling multiplication of solar energy reception stations processed by photovoltaic panels or solar collectors, with minimal engagement of the plot or roof surface area designated for this purpose.

The new proposal allows for utilizing and arranging solar energy collection panels simultaneously in an aesthetic and optimal manner through the use of movable panel structures positioned as needed. The vertical system enables significant space savings while maintaining high energy efficiency.

2025

4(84)

Przemysław Andrzej Stobiecki*

Mobile vertical photovoltaic system

DOI: 10.37190/arc250414

Published in open access. CC BY NC ND license

Abstract

The aim of the article is to present an original alternative technical solution enabling the multiplication of solar energy receiving stations processed by

photovoltaic panels or solar collectors, with minimal involvement of the plot or roof area intended for this purpose. The new proposal makes it possible

to use and arrange solar energy panels not only in a way that absorbs the surface of the plot for panel development as little as possible, but at the same

time in an aesthetic and optimal way by using the structure of movable panels placed in a specic order. The proposed technical solution presented by the

author allows the panels to track the movement of the Sun in the sky at dierent latitudes in dierent seasons of the year, which is of particular importance

in the temperate zone. The proposed solution will also enable the possible cooling of photovoltaic panels, with the forced air movement of installations

operated in conditions of extremely high temperatures during summer days. The technical solution is to be a cheap alternative to the existing solutions that

absorb costs, space, and prevent proper maintenance and upkeep of above-ground or roof installations. Thanks to it, it will be possible to further increase

the eciency of modern installations drawing energy from sunlight. In order to validate the designed solution, the dependence of the inclination of the

selected photovoltaic panel in relation to the Sun and its power was tested.

Key words: photovoltaics, solar panels, two-axis solar tracker, moderate zone, municipal installations

Introduction

The Sun is a gigantic thermonuclear reactor. It is of course

a trivial simplication and unfair pigeonholing of a gor-

geous space phenomenon which is the Sun and the planets

circling around it. We owe our life to this star. Similarly, all

the energy comes from it. In the past and today, it was pro-

duced from minerals, and all forms of renewable energy ob-

tained come from solar energy – it was trapped millions of

years ago indirectly, in various forms, such as coal or hydro-

carbons from the prehistoric world of plants and animals.

Trapped solar energy can be obtained on ad hoc basis

from fuels processed from plants that are currently living

and cultivated. Energy sources can come from the sun’s en-

ergy transferred to water and atmospheric air, manifesting

in the form of sea currents and tides, river water ow, and

wind. Finally, since the 2

half of the 20

century, it can be

obtained directly from solar heat and light radiation. This

is the purest and simplest form of solar energy – the plant

world has been using it since the dawn of life on Earth. In

the 20

century, attempts were also made to use geothermal

and nuclear energy. Work is also underway to ignite a local

energy source: a “miniature sun” trapped in a thermonuclear

reactor. However, the use of the latter three sources is still

associated with technological shortcomings, risks caused

by the unreliability of modern technologies, and extreme-

ly costly environmental consequences of possible failures.

Today, electricity is the most ecient carrier of energy. And

photovoltaics is the most interesting and cleanest option for

obtaining it directly from the sunlight.

Current state of the development

of solar power engineering

Over the last 10 years, we have seen steady development

in photovoltaic cells (often referred to using the PV abbre-

viation). They are no longer a scientic curiosity used in

space exploration research programs and are becoming in-

creasingly popular as components of terrestrial solar power

plants. In small formats, they are used as a tourist, cheap,

and increasingly ecient source of electricity during va-

cation trips through the wilderness. They are also used in

* ORCID:

0000-0002-1767-8737. Faculty of Architecture, Wrocław

University of Science and Technology, Poland, e-mail: przemyslaw.stobiecki

pwr.edu.pl

146

Przemysław Andrzej Stobiecki

households. Photovoltaic cells are produced in increasingly

larger numbers in handy kits and modules installed on the

roofs of single family homes, set up in orchards and gardens.

More and more often they are incorporated in the national

energy network. They are slowly appearing in larger cities

as roof installations or as a source of energy for individual

street lamps, electronic measuring devices, and electronic

municipal equipment.

Cells are still being developed and are becoming increas-

ingly ecient. Currently, cells with eciencies above 40%

are already in use; these that are industrially manufactured

and popular have the eciency of around 20%. Research is

also being conducted on polymer and organic cells or the

cells with structures similar to the mineral ones called per-

ovskites (“Wikipedia: Ogniwo słoneczne” 2024). Solutions

in the form of double-sided cells using reected and dif-

fracted light are also being used (Szymański 2023).

In order to increase the eciency of the systems, the

programs tracking the Sun’s movement across the sky and

rotate the photovoltaic panels are also being developed to

get the optimal position for harvesting solar energy through-

out the year. Mechanical devices called solar trackers which

rotate the panels on one or two axes constitute additional

equipment for solar panel systems but due to the addition-

al costs associated they are not very popular. Their man-

ufacturers report an expected increase in energy yields on

an annual basis. Single-axis solar tracker – an installation

moving along a single axis, vertical or horizontal – accord-

ing to manufacturers’ data, provides up to 20–30% high-

er yields than those recorded for stationary photovoltaics.

dual-axis solar tracker allows photovoltaic panels to move

in two axes, horizontal and vertical, which makes it much

easier to position them perpendicularly to the axis of the

sunlight. The greater range of movement means that energy

production can be increased by up to approximately 40%

compared to a traditional, static structure (Biernaciak 2024).

The development of photovoltaic cell technology should

be accompanied by the simultaneous development of the

most appropriate methods of exposing them to the sunlight.

Panel rotation systems should be popularized and their de-

sign modied in order to reduce costs continuously.

State of research

The latest publications in the international specialist liter-

ature on solar energy harvesting focus on the properties and

eciency of photovoltaic panels themselves, as well as their

construction and chemical composition (Zobaa, Bansal 2011)

and electrical instrumentation (Szymański 2023; Zobaa,

Bansal 2011; Luque, Hegedus 2011; Dubey, Sarvaiya, and

Seshadri 2013). They also discuss alternative ways of ob-

taining energy from the sun (Prinsloo, Dobson 2015). They

describe the optimal exposure conditions for solar energy de-

vices, building on previously acquired knowledge and veri-

fying long-term experience in the operation of solar farms.

A review of several well-known publications from inter-

national literature and online sources leads to the following

conclusion: while we are seeing the progress in the devel-

opment of increasingly ecient and durable photovoltaic

cells, there is virtually no progress in terms of methods of

exposing them to the sunlight and the results achieved so far

seem to be generally satisfying. In this situation, it is neces-

sary to propose renewed attempts to develop systems for ex-

posing photovoltaic panels to the Sun in order to reduce their

costs and increase the eciency of the installations used.

Below there is a brief overview of selected current biblio-

graphic items on renewable energy sources (hereinafter: RES).

They present advanced solar technologies, state-of- the-art

achie vements driving solar innovation and techniques for op-

ti mizing the eciency and eectiveness of energy harvesting.

In the publication by the Częstochowa University of Tech -

nology, Kierunki i perspektywy rozwoju odnawialnych źró

deł energii. Wybrane aspekty [Directions and Prospects for

the Development of Renewable Energy Sources. Selected

Aspects] (Gawlak 2022), it was pointed out that it was the

European Union’s consistent policy on curbing adverse cli -

mate changes related to carbon dioxide emissions that forced

member states to take various measures, including the devel-

opment of the renewable energy sector. The current geopo-

litical situation is causing raw material prices to rise sharply

and energy independence is becoming a key ob jective for

Europe. There is no doubt that renewable ener gy sources

play a key role in this energy transition. Eco-energy solu-

tions guarantee zero carbon dioxide emissions which is usu-

ally seen as the main advantage of renewable energy. Cur-

rently, energy-importing countries attach great importance

to locally sourced renewable energy.

Among the new publications addressing the issue of re-

newable energy sources and their development in Poland, an

important place is occupied by a unique publication devoted

to technical and organizational issues related to photovolta-

ic installations, including descriptions of their potential uses

and integration into the country’s power system: Instalacje

fotowoltaiczne w systemie elektroenergetycznym [Photovol-

taic Installations in the Power System] (Piątek, Hanzelka

2023). It focuses on the problems of photovoltaic (PV) in-

stallations working with the power grid, especially on the

impact of these sources on the quality of electricity supply

in power systems. The theoretical basis for the operation of

both solar installations (PV cells, inverters) and the issue

of connecting PV installations to the distribution network

were also discussed. The technical conditions for connect-

ing PV installations in Poland and abroad were compared

and the principles of forecasting energy generation by solar

power plants were explained. The book contains numerous

examples and references to the practical use of renewable

energy sources. In addition, the appendix presents a sample

functional and utility program for a 500 kW PV installation.

Similar issues are discussed in a more recent publica-

tion: Podstawy elektroenergetyki [Fundamentals of Electri-

cal Power Engineering] (Kacejko, Pijarski 2024), which is

a compendium of electrical power engineering knowledge

with a particular focus on photovoltaics and wind energy. It

also describes important issues related to the energy transi-

tion and electrical power security in Poland. The paragraphs

devoted to the basics of protection automation and the con-

trol and management of power systems, as well as the qual-

ity of the electricity obtained are noteworthy. Examples of

computer software currently used in the power industry are

cited and described here.

Mobile vertical photovoltaic system 147

The book Designing and Installing Solar PV Systems

(Warm ke 2022) is a guide to designing commercial installa-

tions and large residential solar systems – at an advanced lev-

el. It extends the knowledge of photovoltaic installations in

homes to the eld of commercial project installations. It also

addresses project management issues. The guide has been up-

dated in accordance with the changes introduced in NFPA 70:

National Electrical Code 2020, binding in the United States.

In turn, the publication Fundamentals of Solar Cells and

Photovoltaic Systems Engineering (Victoria 2024) covers all

topics relevant to understanding of photovoltaic technology,

including: the principles of solar cell operation, modelling

and measurement of solar radiation, the manufacturing pro-

cesses of solar cells and photovoltaic modules, the design

and operation of rooftop installations and large-scale power

plants, the economics of such systems, and the role of photo-

voltaic solar energy in the ongoing energy transition. It also

examines innovative PV system designs, including agrivol-

taics and energy communities based on PV installa tions on

shared roofs. This outstanding publication is intend ed to

serve as a guide and handbook on photovoltaic solar energy

and is addressed to engineers and engineering students at

university level in Spain and around the world.

Solar Energy (Botwright 2024), a book promoting the use

of solar energy, addresses extremely important issues related

to photovoltaics in several chapters. It is an ideal starting

point for anyone ready to use renewable energy, as well as

for those who want to minimize costs and reduce their car-

bon footprint.

Inspirations from the world of plants

When it comes to industrial energy harvesting from sun-

light, it is worth emulating the solutions tested and invented by

the plant world, which draws its life energy from photosynthe-

sis – this is undoubtedly the most eective solution possible.

In the world of plants originating from temperate zones

(e.g., sunowers, soybeans, cotton), heliotropism is a pop-

ular ability is (Fig. 1), it is sometimes called sun tracking

– the ability of leaves or owers to change their orientation

in response to the Sun’s position. Often, plant’s leaves po-

sition themselves so that the sun’s rays fall perpendicularly

on them, regardless of the time of the day, which increases

the absorption of sunlight energy.

Fig. 1. Plant heliotropism (Salomon, Berg, and Martin 2007, 696)

Il. 1. Heliotropizm roślin (Salomon, Berg i Martin 2007, 696)

Fig. 2. Energy [Mtoe] obtained from various sources worldwide

between 1970 and 2022. Logarithmic scale

(source: Wikimedia Foundation. “Wikipedia: Odnawialne źródła energii.”

Accessed September 13, 2024, https://pl.wikipedia.org/wiki/

Odnawialne_%C5%BAr%C3%B3d%C5%82a_energii#cite_note-bp19-7)

Il. 2. Energia [Mtoe] uzyskana z różnych źródeł na świecie

w latach 1970–2022. Skala logarytmiczna

(źródło: Wikimedia Foundation. “Wikipedia: Odnawialne źródła energii.”

Dostęp 13 września 2024, https://pl.wikipedia.org/wiki/

Odnawialne_%C5%BAr%C3%B3d%C5%82a_energii#cite_note-bp19-7)

Crude oil

Nuclear energy

Remaining preventable: bio-fuels,

geothermal energy and other

Hydropower

Natural gas

Coal

Wind energy

Sun energy

Fig. 3. Capacity [GW] of wind (blue), solar (yellow)

and geothermal (red) wind farms in the world in 1992–2018.

Logarithmic scale (source: Wikimedia Foundation.

“Wikipedia: Odnawialne źródła energii.” Accessed September 13, 2024,

https://pl.wikipedia.org/wiki/

Odnawialne_%C5%BAr%C3%B3d%C5%82a_energii#cite_note-bp19-7)

Il. 3. Moc [GW] elektrowni wiatrowych (niebieski),

słonecznych (żółty) i geotermalnych (czerwony) na świecie

w latach 1992–2018. Skala logarytmiczna

(źródło: Wikimedia Foundation. “Wikipedia: Odnawialne źródła energii.”

Dostęp 13 września 2024, https://pl.wikipedia.org/wiki/

Odnawialne_%C5%BAr%C3%B3d%C5%82a_energii#cite_note-bp19-7)

Designing the ways of photovoltaic panels exposition we

should be inspired by the solutions from the world of nature.

Development of power engineering in recent years

The statistical data showing the actual degree of utiliza-

tion of solar photovoltaic cells in the global energy balance

are worth reviewing. The charts below allow you to assess

possible trends in the development of modern energy sourc-

es in the coming years (Figs. 2, 3).

148

Przemysław Andrzej Stobiecki

consists of over 150,000 Jinko Solar polycrystalline mod-

ules with a maximum eciency of 20.13%. The cables have

a total length of 900 km. The farm’s annual eciency is

68 GWh, which corresponds to the annual electricity con-

sum ption of approximately 22,500 average households in

Po land. Currently, the Witnica solar farm belongs to the Irish

ompany Alternus Energy Group.

PV powerplant in Wielbark

In October 2022, the construction of a 62 MW photovol-

taic farm located near Wielbark (Warmian-Masurian Voi vo-

deship) was completed. It will supply energy to over 30,000

households. Approximately, it consists of a total of 140,000

panels with a unit capacity of up to 530 W. The installations

are operated by 337 inverters. The construction of the farm

required 56 permits and the use of almost 2,500 tons of

steel. The farm was built on an area of 119 ha, mainly low-

grade arable land. The project was implemented by Ener-

ga Wytwarzanie, a subsidiary of Energa from the ORLEN

Group. Wielbark solar farm began operating at full capac-

ity in the rst quarter of 2023. There are plans to expand it

with additional transformer stations, increasing its connec-

tion capacity and enabling the safe reception of the energy

generated. At an earlier stage of the investment in the farm,

commercial production was carried out using 12 MW panels

connected to the transmission grid.

PV powerplant in Stepień

In October 2022, the construction of a 58 MW photo-

voltaic farm in Stępień (Warmian-Masurian Voivodeship)

was completed. The investment was carried out and will be

managed by Wento, a company owned by Equinor (former-

ly Statoil). The solar farm consists of 100,000 solar panels

spread over an area of 65 ha. It will produce 61 GWh of

energy per year, which corresponds to the demand of ap-

proximately 31,000 Polish households.

PV powerplant in Czerników

The solar power plant in Czerników near Toruń has an

installed capacity of 3.77 MW. The PV power plant covers

an area of approx. 7.7 ha. The installation consists of nearly

16,000 panels, with the capacity of 240 W each, covering

an area of over 22,500 m

, which corresponds to the size

of several football elds. The annual electricity production

in Czerników is estimated at 3,500 MWh, which is su-

cient to meet the needs of approx. 1,600 households. The

power plant has a container transformer station consisting

of a low-voltage switchgear, a transformer chamber, and

a medium-voltage switchgear with a control room and an

underground cable connection to the 15 kV MV line.

Sun powerplant in Bierutów

The solar farm in Bierutów (Lower Silesian Voivode-

ship) was built in the second half of 2018. Its installed ca-

pacity is 2.059 MW. The installation consists of 7,920 pho-

tovoltaic panels, with a capacity of 260 Weach. The owner

Mtoe is a megaton of oil equivalent, toe is the energy

equivalent of one metric ton of crude oil with a caloric value

of 10,000 kcal/kg. This unit is used in the energy sector to

describe large amounts of energy (“Wikipedia: Ton of oil

equivalent”).

The charts from recent years show the most dynamic

growth in solar energy sources.

The state of photovoltaic solar power engineering

in Poland

The installed capacity of photovoltaics in Poland at the

end of September 2022 amounted to over 11 GW (Urząd

Regulacji Energetyki 2024). On April 30, 2024, the Presi-

dent of the Energy Regulatory Oce published an annual

report on electricity generation in small renewable ener-

gy installations in 2023. According to the report, approx.

3.5 GW was obtained from so-called small photovoltaic

installations (Energy Regulatory Oce). Currently, photo-

voltaics in Poland accounts for more than half of the total

installed capacity of renewable energy sources. The exam-

ples of some of the largest Polish photovoltaic farms are

presented below (Urząd Regulacji Energetyki 2024).

PV Sun farm in Zwartowo

The power plant in Zwartowo (West Pomeranian Voi-

vodeship is the largest solar farm in Poland. Its capacity

is 204 MW. It is also the largest solar installation in Cen-

tral-Eastern Europe. The farm covers the area of 300 ha

(equivalent to 422 full-size soccer elds). It was built by

Respect Energy S.A. in cooperation with the German com-

pany Goldbeck Solar. The rst stage of the farm, with a ca-

pacity of 204 MW, was completed in September 2022. The

planned second stage aims to increase the total capacity to

290 MWp, which will allow the farm to maintain its leading

position. The Zwartowo farm will produce approximately

230 GWh of green energy per year. This will power 153,000

households – the total number of households in Gdańsk.

PV powerplant in Brudzewo

The Brudzewo power plant (Wielkopolskie Voivodeship)

with a capacity of 70 MW was built by the ESOLEO consor-

tium for the ZE PAK group. The construction was complet-

ed in October 2021. The farm consists of 155,554 photovol-

taic modules with a capacity of 450 Wp (this abbreviation

refers to the amount of electricity at peak production) each

and covers the area of approximately 100 ha. Previously,

the area was used by the Adamów mine for opencast lignite

mining. In addition to the modules, 306 inverters and over

900 km of cables and bre optics were used to build the

power plant. There are 31 transformer stations on the power

plant premises, each with a capacity of 2 MVA.

PV powerplant in Witnica

A 64 MW solar power plant is located in Witnica (Lubus-

kie Voivodeship). The facility was built by BayWa r.e. Elec-

tricity production began in early 2021. The Witnica farm

Mobile vertical photovoltaic system 149

has been granted a license to generate electricity until the

end of 2030.

Sun powerplant in Cieszanów

In 2014, a solar power plant was built in Cieszanów near

Lubaczów (Podkarpackie Voivodeship). The solar power

plant, located on a 4.5-hectare plot, has 8,333 polycrystal-

line photovoltaic panels, each with a rated power of 240 Wp

(kWp kilowatt-peak). The total power of the plant is 2 MW.

Sun powerplant in Ostrzeszów

The solar farm in Ostrzeszów has a capacity of 2 MWp.

It was built on an area of 3.33 ha. The surface area of the

photovoltaic modules is 11,155 m

. The farm consists of

8,064 monocrystalline photovoltaic modules with a peak

capacity of 250 Wp.

None of the above-mentioned power plants uses rotating

sun-tracking systems and occupies a large area of poor soil

with high bonitation value.

The description of own research

Materials and methods

The measurement tests were limited to examining the

impact of the inclination of solar panels on the direct current

values appearing in them. No tests were conducted on sets

converting direct current into alternating current. When de-

scribing the illumination conditions for the panels, the focus

was on European conditions. Particular attention was paid

to the latitude of the author’s hometown, Wrocław (Lower

Silesian Voivodeship). Wrocław is located at approximately

+51°06′0′′ north latitude (N+, S–) and –16°46′0′′, in a time

zone with an UTC oset of –1. The calculations and dia-

grams do not take into account daylight saving time chang-

es. The measuring station was set up at a height of 7 m above

ground level in Wrocław, at an elevation of 119.55 m above

sea level. On December 21, 2020, between 11:45 a.m. and

12:15 p.m., i.e., during outdoor measurements, the ambient

temperature was +4°C. Weather conditions were favour-

able: it was a sunny day with visibility exceeding 10 km.

Atmospheric pressure was 1046.4 hPa. The temperate illu-

mination zones of the Earth almost coincide with the geo-

graphical temperate zones, or rather the temperate latitudes

(Fig. 4). They are located in areas in both hemispheres, be-

tween the tropics and the polar circles. They are adjacent to

the polar zones and the inter-tropical zone. The intensity of

solar radiation throughout the year varies at dierent lati-

tudes on Earth. The northern and southern temperate zones

receive the most radiation when the days are long, i.e., in the

spring and summer months.

In the areas of moderate illumination there is no polar

day or polar night and the sun never reaches its zenith. On

the summer solstice the sun reaches an altitude of almost

90° above the horizon near the Tropic of Cancer. At this

time near the Antarctic Circle the Sun reaches just over 0°.

In Wrocław the Sun reaches an altitude of 62°40′1″. During

the winter solstice the Sun is at the Tropic of Capricorn.

Fig. 4. Zones of moderate illumination of the globe and zones

of temperate zones latitude (source: https://commons.wikimedia.org/

wiki/File:Temperate_zone_(PSF).png)

Il. 4. Strefy umiarkowanego oświetlenia kuli ziemskiej oraz strefy

umiarkowane szerokości geograficznych (źródło: https://commons.

wikimedia.org/wiki/File:Temperate_zone_(PSF).png)

At this time, it shines almost 43° above the horizon at the

Tropic of Cancer and only 16°0′6″ in Wrocław. This causes

a large variation in the length of day and night. In Poland

the longest day (the rst calendar day of summer) lasts from

4:10 p.m. in the south to 5:20 p.m. in the north. The shortest

day (the rst day of calendar winter) in the north is more

than 10 hours shorter and in the south of Poland – almost

8 hours shorter. Additionally, regardless of the season, on

sunny days from dawn to dusk, the sun “wanders” across

the sky from a position of 0° above the horizon at dawn to

0° above the horizon at dusk. At noon it reaches its maxi-

mum height above the horizon. Every day (in one of the two

halves of the year) this height is always dierent.

Based on data collected from the Sun position calculator

(Global Monitoring Laboratory) curves of its position in the

sky above Wrocław were determined on the days of measu-

rement: December 21, 2020, and June 21, 2021. These are

the days of the lowest and highest position of the sun at

noon above the horizon as seen from Wrocław.

When preparing analyses for other illumination zones

and locations with dierent geographical coordinates dier-

ent measurement results and sun positions in the sky should

be expected.

When looking for the best placement and tilt of the panels

for known sun positions above the horizon the angle of the

sun above the horizon from 90° should be subtracted. For

the most common photovoltaic installations in Poland, i.e.,

those mounted on roofs or on xed pedestals in gardens and

elds, the recommended angle of the panels, measured from

the ground level, should range from 30° to 40° (according

to companies installing stationary photovoltaic

panels; Byś

2023), which translates into the optimal positioning of pho-

tovoltaic panels for the sun at an altitude of 50° to 60° above

the horizon. As shown in Figure 5 for the latitude of Wrocław

this is the correct inclination in the middle of the day at the

end of spring, summer, and the rst weeks of autumn. Un-

fortunately, for the rest of the year – when the days become

shorter, colder, and cloudier – the recommended panel set-

ting does not allow for the full power of the photovoltaic

installation to be achieved, even during sunny spells. These

panels occupy a relatively large area – to achieve 1 kW of

peak power the required cell area is approx. 7 m

(Byś 2023).

150

Przemysław Andrzej Stobiecki

On December 21, 2020, between 11:45 a.m. and 12:15 p.m.,

tests were conducted in Wrocław to measure the direct cur-

rents occurring in a new photovoltaic panel manufactured and

sold in 2020, constructed from monocrystalline cells (4 pcs.

× 9 pcs. = 36 pcs.).

The panel manufacturer provided the following speci-

cations:

– exible solar module,

– module type: HNPV-100M,

– peak power (PMP): 100 W,

– manufacturing tolerance: ±3%,

– open circuit voltage (VOC): 21.6 V,

– maximum power current (MP): 6.05 A,

– maximum power voltage (VMP): 18.00 V,

– short-circuit current (Isc): 5.56 A,

– maximum system voltage: 1000 V,

– product dimensions: 1200 × 550 × 2.5 mm,

– all technical data under standard test conditions,

– AM = 1.5 E = 1000 W/M

TC = 25°C,

– CE ISO 9001 – 2008 ROHS.

The study was designed to determine the eciency of the

tested panel which is exposed to sunlight at various angles

and the characteristics of these relationships as well as to

assess the values of the obtained voltages, intensities, and

DC currents when changing the position of its plane in rela-

tion to the light source, i.e., the Sun. A voltmeter was used

to measure the DC voltage while an ammeter and a sys-

tem with a light bulb drawing current from the photovolta-

ic panel were used to measure the DC current. The results

obtained do not exceed the maximum values, taking into

account the ±3% tolerance guaranteed by the manufacturer.

Results

The results obtained are presented in the graphs (Figs.

6–8). The y-axes (vertical) show the measured and calculat-

ed values: DC voltage, DC current, DC power. The x-axes

(horizontal) show the slope of the tested photovoltaic panel

during the measurements in degrees and tenths of degrees.

The inclination of 163.94° means that the panel is facing

downwards with its photovoltaic plane lying in the plane de-

termined by the position of the Sun on December 21, 2020,

at 12:00 p.m. in Wrocław. Similarly, the angle of inclination

is –16.06° but for the panel facing upwards. On that day and

at that time in Wrocław, the Sun’s rays fell perpendicularly

on the plane panel positioned at an angle of 73.94°. Detailed

values are also listed below the graphs.

The recorded results allow for the calculation of the

direct current generated in the photovoltaic panel.

The red colour indicates the levels of direct current pro-

duced by the panel and lost due to poor orientation of the

panel relative to the Sun. The total amount of lost energy

reaches 22–35%.

Conclusions

The actual levels of prot or loss generated by xed pan-

els and sun-tracking panels can be determined by compar-

ing installations with identical parameters installed close to

each other, in an identical environment over a longer period

of time, e.g., a year or several years. The results of research

and analyses clearly indicate the advantage of sun-tracking

panels throughout the year. As already mentioned, research

shows that immobilizing modern photovoltaic panels leads

to unnecessary losses. Not only the further development of

photovoltaic cells is necessary but also is the widespread use

of dual-axis devices that move the panels commonly known

in Poland as trackers. All this aims at making fuller use of the

Sun’s energy reaching the Earth.

The analyses carried out enable us to propose new, origi-

nal solutions which are presented below.

Reduction of costs of rotating systems that track the

sun’s movement across the sky should be the main goal of

designers. Stacking photovoltaic panels on a single rotating

device may be an interesting method of reducing the costs of

planned installations. Detaching photovoltaic farms from the

ground and placing them on poles will free up between one-

third and two-thirds of the space they currently occupy. One

can imagine multi-story installations spaced at certain dis-

tances from each other in such a way that the shadow of the

high-placed panels wandering across the Earth’s surface will

not interfere with the vegetation of low and medium-sized

plants growing around them. This makes it possible to build

photovoltaic farms not only on wasteland but also on farm-

land. Such solutions erected in sunny locations on lawns,

squares or along existing streets, may become a popular al-

ternative to urban rooftop photovoltaic installations.

When correctly positioned, rotating systems can not only

provide solar energy but also provide welcome shade on

summer days in urban areas and streets. By creating screens

Fig. 5. The height of the Sun above the horizon in Wrocław, from sunrise to sunset in hours. The slope of fixed photovoltaic panels recommended

by producers in Poland is marked in green (elaborated by P. Stobiecki)

Il. 5. Wysokość słońca nad horyzontem we Wrocławiu od wschodu do zachodu słońca co godzinę; na zielono zaznaczono nachylenie stałych

paneli fotowoltaicznych rekomendowane przez producentów w Polsce (oprac. P. Stobiecki)

Mobile vertical photovoltaic system 151

Fig. 6. The voltage of direct current, a photovoltaic panel laid at different angles, on a day 21.12.2020, in hours 11.45–12.15

(elaborated by P. Stobiecki)

Il. 6. Napięcie prądu stałego, panel fotowoltaiczny ułożony pod różnymi kątami, 21 grudnia 2020 r., godz. 11.45–12.15

(oprac. P. Stobiecki)

Fig. 7. The intensity of direct current, a photovoltaic panel laid at different angles, on a day 21.12.2020, in hours 11.45–12.15

(elaborated by P. Stobiecki)

Il. 7. Natężenie prądu stałego, panel fotowoltaiczny ułożony pod różnymi kątami, 21 grudnia 2020 r., godz. 11.45–12.15

(oprac. P. Stobiecki)

Fig. 8. The work of direct current, a photovoltaic panel arranged at different angles, on a day 21.12.2020, in hours 11.45–12.15

(elaborated by P. Stobiecki)

Il. 8. Praca prądu stałego, panel fotowoltaiczny ułożony pod różnymi kątami, 21 grudnia 2020 r., godz. 11.45–12.15

(oprac. P. Stobiecki)

from photovoltaic panels placed high on rotating poles an

additional cooling eect can be expected in urban areas du-

ring the summer months. Figure 9 shows the author’s pro -

posal for a new type of tracker solution.

The proposed solution is equipped with additional sprin-

kler and cooling systems for the panels during the summer

months. Placing several panels vertically above each other

on a single rotating pole makes this solution more economi-

cal ly viable. The panels in the lowest position should be

located approximately 2.5 m above the ground. They are

arranged in such a way that at no time of the day or year

do they obscure those located above and below. The total

height of the solution shown is approximately 10.5 m. The

presented variant, provisionally named type “A”, consists of

8 identical photovoltaic panels with an example power of

280 W. The total power of such an installation is 2.24 kW.

Solutions for a larger number of panels attached to the same

mast are in preparation:

– “B” for installations with 12 panels with a total power

of 3.36 kW,

– “C” for installations with 17 panels with a total power

of 4.76 kW,

– “D” for installations with 18 panels with a total power

of 5.04 kW,

– “E” for installations with 22 panels with a total power

of 6.16 kW,

– and a slightly larger “F” for installations with 36 panels

with a total power of 10.08 kW.

152

Przemysław Andrzej Stobiecki

In urban areas such as Wrocław, there are streets that are

almost ready for the installation of photovoltaic panels in

vertical arrays. Plac Grunwaldzki is a spectacular example.

It extends from southwest to northeast. Existing street lamp

posts, approximately 12 m high and spaced every 25 m, can

be used to install suitably adapted vertical rotating panel in-

stallations. Separate new-type tracker poles with panels can

also be added.

The northern side of this street (on the right in Fig. 10)

seems to be particularly well suited for the installation of

vertical photovoltaic systems. This is due to the shape of the

low and high greenery, the appropriate urban development,

and the favourable solar exposure.

Advantages of the proposed solution

The new type of dual-axis tracker has several signicant

advantages. Some of them are the advantages of all dual-ax-

is low trackers used to date. However, the proposed solution

will save more costs, space, and energy losses. Among the

advantages, the following are worth mentioning:

– increasing the eciency of sunlight capture, leading

directly to improved performance of the photovoltaic instal-

Fig. 9. A proposal for a new type of vertical, rotating, biaxial photovoltaic system solution: a) side view; b) frontal perspective; c) axonometry side.

1 – photovoltaic panels, 2 – axis of rotation of panel hangers, 3 – panel hanger, 4 – hanger tie rod motor, 5 – main rigid tie rod of hangers,

6 – steel tube of the rotating column structure, 7 – steel foundation tube with a motor rotating the pole, 8 – reinforced concrete footing,

9 – sprinkler water system, 10 – cooling air supply system (designed by P. Stobiecki)

Il. 9. Propozycja rozwiązania wertykalnego, obrotowego, dwuosiowego układu fotowoltaicznego nowego typu: a) widok boczny,

b) perspektywa od przodu, c) aksonometria boczna. 1 – panele fotowoltaiczne, 2 – osie obrotu wieszaków paneli, 3 – wieszak panelu,

4 – silnik cięgna wieszaków, 5 – sztywne cięgno główne wieszaków, 6 – stalowa rura konstrukcji obrotowego słupa,

7 – stalowa rura fundamentowa z silnikiem obracającym słup, 8 – żelbetowa stopa fundamentowa, 9 – instalacja wody do tryskaczy,

10 – instalacja nawiewu chłodzącego (projekt: P. Stobiecki)

lation (average annual energy production is by 29% higher

compared to traditional photovoltaic installations; Energe -

tyka-Sloneczna.Net),

– installation is an important step towards energy self-suf-

ciency, but also serves the environment protection,

–

movement of solar panels reducing the likelihood of dust

and other contaminants settling on them (Biernaciak 2024),

– support for the system with sprinkler and ventilation

installations,

– more convenient access to the panels (e.g., if cleaning,

repair, or maintenance is required, a photovoltaic installa-

tion with a tracker can be easily positioned in a convenient

location, which is a great convenience, especially in the case

of panel failure inside the installation; Biernaciak 2024),

– movable panels enabling automatic snow removal in

winter,

– benets and savings arising from the reduction of land

and acreage occupied,

– vertical arrangement of panels on a single rotating

pole resulting in reduced costs compared to previously used

solutions in the form of single-story trackers,

– the function of shading selected urban areas leading to

lowering the temperatures in summer.

Mobile vertical photovoltaic system 153

The advantages listed above can signicantly reduce the

costs associated with planned investments.

The costs as well as a certain sensitivity to damage to the

drive systems are the main disadvantages of the proposed

sun tracking systems which are exposed to weather condi-

tions. Final decision on the cost-eectiveness of the pro-

posed solutions must be preceded with appropriate research

in this area. Without it is dicult to estimate how protable

will be the proposed solution compared to less complicated

immobile systems. However, the economic aspect was not

the focus of this study. Such research needs to be conducted

as part of a separate project.

Nevertheless, there is hope that this study will encourage

solar system designers and all those interested in this topic

to work hard to promote inexpensive, eective vertical pho-

tovoltaic systems in urban and rural areas.

Summary

The study conducted and the results obtained are of a ge-

neral nature. The conclusions drawn from them may be ap -

plicable to other positions of the Sun in the sky or other

days of the year for the selected location. The losses shown

are actually multiplied and translated into the annual perfor-

mance of photovoltaic panels, which are traditionally xed

on pedestals without the possibility of changing their posi-

tion in relation to the Sun. With various poor panel settings

electricity is lost according to the percentage breakdown

shown in Table 1.

The percentages in the table cells at the border between

the white and red rows reach the level of value loss measured

in the range of 3–5%. They can be considered the margin of

error of the measurements obtained in the experiment. The

area of obvious losses resulting from the mismatch between

the inclination of the photovoltaic panels and the maximum,

optimal sunlight conditions is marked in red. The colour code

also corresponds to the data obtained in the scheme in Figure

8. At photovoltaic panel inclinations of –16.06° and 163.94°,

voltages of 20 V and currents of 1 A were recorded.

These inclinations are extremely unfavourable for the

operation of the photovoltaic panel on December 21, 2020,

at 12:00 p.m. and prevent the absorption of direct sunlight.

Nevertheless, the recorded voltage and current values are

dierent from zero and indicate the appearance of current

values in the system caused by light reected from the envi-

ronment and scattered water vapor in the atmosphere during

the test. Currents from scattered light nearly always appear.

The energy generated by sunlight reections is used in

double-sided photovoltaic panels. Their eciency can be

Fig. 10. The perspective of Plac Grunwaldzki street in Wrocław

and its favourable arrangement for municipal vertical photovoltaic

installations (photo by P. Stobiecki)

Il. 10. Perspektywa ulicy Plac Grunwaldzki we Wrocławiu

i jej korzystne ułożenie dla miejskich pionowych instalacji

fotowoltaicznych (fot. P. Stobiecki)

Panel tilt downward from

73.94

Panel tilt upward from

73.94

% work related to maximum

% decrease of efficiency related to

maximum

73.94 73.94 100.00 0.00

70 80 97.78 2.22

60 90 96.91 3.09

50 100 96.46 3.54

40 110 94.74 5.26

30 120 93.45 6.55

20 130 86.25 13.75

10 140 73.30 26.70

0 150 41.71 58.29

–16.06 163.94 39.51 60.49

Table 1. Percentage loss of direct current work, photovoltaic panel laid at different angles,

on a day 21.12.2020, in hours 11.45–12.15*

(elaborated by P. Stobiecki)

Tabela 1. Procentowa strata pracy prądu stałego, panel fotowoltaiczny ułożony pod różnymi kątami,

21 grudnia 2020 r., godz. 11.45–12.15* (oprac. P. Stobiecki)

* The optimal angle of the panel on December 21, 2020, at 12:00 p.m. from the horizon: 73.94°; it allows sunlight to fall perpendicularly to the panel

surface. Position of the Sun in Wrocław: 16.06° above the horizon.

154

Przemysław Andrzej Stobiecki

increased by up to 25% (Szymański 2023). To fully utilize

the eects of reected light double-sided panels should be

placed at considerable heights above the ground or roofs.

In the experiment the eciency losses of the tested sys-

tem for angles ranging from –16.06° to 40° and from 110°

to 163.94° correspond to the losses that occur in permanent-

ly installed photovoltaic panel systems in the morning and

evening hours. Such losses are particularly severe in the

sum mer months when the normal operation of photovol-

taic panels is disrupted by high ambient temperatures and

the heating of the panel. According to experiment, losses

caused by temperature increases in the daily energy balance

reach 0.4% per 1°C (Dubey 2013). The balance can be im-

proved by tracking the position of the Sun with a dual-axis

tracker which will ensure maximum power supply in the

mor ning and evening on a summer day (with moderate tem-

peratures).

Research shows that the immobilization of modern pho-

tovoltaic panels leads to losses. These losses, regardless of

the level of atmospheric light, are a year-round, common and

unnecessary phenomenon. Given the current popularity

of solar energy which draws energy from photovoltaics as

well as the trends in the development of this type of energy

production every eort should be made to reduce the cost

of devices that track the Sun’s movement in the sky which

will allow for their widespread use. This, in turn, will elim-

inate energy losses resulting from the misalignment of the

panels.

Numerous studies on the intensity of sunlight show that

during the winter months and in the early morning and late

afternoon hours in summer, the intensity of sunlight is only

seemingly lower. The intensity of sunlight can be around 60%

of its maximum value when the Sun is 15° above the horizon,

around 50% at 10°, and 25% at just 5° above the horizon.

Therefore, if trackers can follow the Sun from sunrise to sun-

set their rotating solar panels can collect a signicant amount

of additional energy (“Wikipedia: Solar tracker”).

Translated by

Agata Haglauer

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Patents

Patents for the abovementioned designs of vertical dualaxis trackers of

types “B”, “C”, “D”, “E”, and “F” are planned to obtain.

Mobile vertical photovoltaic system 155

Streszczenie

Ruchomy pionowy system fotowoltaiczny

Celem autora artykułu było przedstawienie oryginalnego alternatywnego rozwiązania technicznego umożliwiającego multiplikację stanowisk odbioru

energii słonecznej przetwarzanej przez panele fotowoltaiczne lub kolektory słoneczne, przy minimalnym zaangażowaniu powierzchni przeznaczonej na

ten cel działki lub powierzchni dachowej. Nowa propozycja pozwala na wykorzystanie i ułożenie paneli gromadzących energię słoneczną równocześnie

w sposób estetyczny i optymalny poprzez wykorzystanie konstrukcji ruchomych paneli umieszczanych według określonego porządku. Rozwiązanie to

może być alternatywą także dla połaciowych dachowych przydomowych instalacji fotowoltaicznych lub kolektorów słonecznych.

Propozycja rozwiązania technicznego przedstawiona przez autora pozwala na śledzenie przez panele ruchu słońca na nieboskłonie pod różnymi szero-

kościami geogracznymi w różnych porach roku, co ma szczególne znaczenie w stree umiarkowanej. Możliwe są także obrót paneli i optymalizacja ich

położenia w trakcie każdego dnia roku, od świtu do zmierzchu. Proponowane rozwiązanie umożliwi ponadto ewentualne chłodzenie paneli fotowoltaicz-

nych wymuszonym ruchem powietrza instalacji eksploatowanych w warunkach ekstremalnie dużych temperatur podczas dni letnich.

Proponowane rozwiązanie ma być tanią alternatywą dla dotychczasowych instalacji naziemnych lub dachowych, absorbujących koszty i powierzchnię

oraz uniemożliwiających należyte utrzymanie i konserwację. Dzięki niemu możliwe będzie dalsze zwiększanie efektywności nowoczesnych instalacji

pobierających energię ze światła słonecznego.

W celu uwiarygodnienia projektowanego rozwiązania przeprowadzono badania zależności nachylenia wybranego panelu fotowoltaicznego względem

słońca i jego uzyskiwanych mocy.

Słowa kluczowe: fotowoltaika, panele solarne, tracker słoneczny dwuosiowy, strefa umiarkowana, instalacje miejskie