Ritter Solar GmbH & Co. KG

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Evacuated tube collectors

CPC 6 OEM / INOX CPC 12 OEM / INOX CPC 18 OEM / INOX

Planning Guide



Planning Guide CPC 6/12/18 OEM / INOXRitter Solar / 2007 2

Imprint

Technical data subject to change!

Due to constant further development, illustrations, assembly steps, and technical data can differ.

Manufacturer‘s address:

Ritter Solar GmbH & Co. KG · Kuchenäcker 1 · 72135 Dettenhausen · Germany

Phone +49(0)7157/5359-0 · Fax +49(0)7157/5359-20

[email protected] · www.rittersolar.de

Document no.: TDUK1010 V 1.3

Date of issue: 05/07

Copyright: All information specified in this technical document as well as the designs and technical descriptions made available

by us remain our property and may not be reproduced without our prior written permission.




Table of contents

Table of contents

Page

Imprint 2

Table of contents 3

1. General information 4

2. Benefits and advantages 5

3. Design and function of the collectors 6

4. Technical data 9

4.1 Technical specifications for CPC 6/12/18 OEM / INOX 9

4.2 Pressure drop 10

5. Heat output 11

6. Configuration of the collector area 13

7. Notes on solar controllers 15

8. Configuration of the collector connecting pipes 16

9. Configuration of the expansion vessel size 17

10. Connection possibilities 19

11. Installation example 21

11.1 Installation example of a solar water heating system 21

11.2 Installation example of a solar water heating system with heating support 21

12. Assembly instructions 22

12.1 Space requirement with pitch roofs 22

12.2 Space requirement with flat roofs 23

12.3 Weight and placement of the concrete plates with flat roofs 24

12.4 Space requirement with perpendicular façade assembly 25

12.5 Space requirement with façade assembly with angle frames 45° or 60° 26

12.6 Specifications 27

12.7 Solar roof heating center 28

13. Certificate Solar Keymark 29






2Benefits and advantages

2. Benefits and advantages

Intelligent design and assembly:

• Suitable for pitch roof and flat roof mounting as well as for the free standing mounting and façade assembly• For heating of drinking water and operating water for part-solar heating and swimming pool water, as well as

for solar cooling

• High flexibility through collector modules with varying widths

• Connectable up to 15 m2 in series

• Outstanding Design

• Short assembling times due to completely prefabricated collector units and simple flexible rooftop and flat

roof assembly sets

• Simple connection technique for the extension of several collectors next to each other with pre-mounted

connectors. No further pipe work or extensive thermal insulation required

• Solar advance and return flow can take place alternatively on the left of or on the right at the collector

• Exchange of the tubes is possible without emptying of the collector circuit - „dry binding“

• Simple connection of the hydraulic lines by clamping ring connector technology.

Operating reliability:

• High working reliability and long service life by application of high-quality, corrosion-proof materials like

thick-walled borosilicate glass, copper, and corrosion-coated aluminum.

• Permanent vacuum-tightness of the tubes, due to pure glass fusion, no metal-glass transitions, principle

thermos flask.

• High working reliability by „dry binding“ of the evacuated tube to the solar set.

Recycling:

Fully recyclable by dismantle-friendly construction and reusable materials.

Energy yield and performance:

• Extremely high energy yield with small collector gross area.

• Due to circular absorber area, each individual tube has always the optimal adjustment towards the sun.

• Unusually high solar covering rates possible.

• High efficiency through highly selective absorber coating.

• The evacuated tubes reduce the thermal losses of a solar collector with high efficiency, since in the vacuum

there is no air which could transport the heat from the absorber surface to the external glass tube which is

subject to weather influences.

• The heat distribution medium is conducted directly through the tube without a heat exchanger inserted intothe collector.

• Both direct and diffuse solar radiation at varying irradiation angles are always optimally collected by the

circular absorber.

• The CPC mirror and the direct flow through the evacuated tube contribute substantially to the extremely high

energy yield.

• Optimum thermal insulation by vacuum, thereby high efficiencies also even in the winter season and at low

irradiation.

• Unused surplus in summer is lower than with a flat-panel collector. But the gains in winter are substantially

higher.

• Ideally suited also for low-flow systems with layer load and heating support.




3Design and function of the collectors

3. Design and function of the collectors

Historical roots – the invention of the thermos flask

In 1893, Scottish physicist James Dewar invented a double-walled vessel with a vacuum-insulated gap - the

thermos flask.

Based on the principle of the thermos flask, already in 1909 Emmet developed evacuated tubes in order to make

solar power usable. Even today, his patents from that time are the basis for modern evacuated tube technology.

However, the efficiency of this old and well-known technology of the thermos flask could be brought to the highest

level only with the help of modern coating technologies and highly selective layers.

The technology - today

The Ritter Solar evacuated tube collector consists of 3 main components which are completely pre-assembled:

• evacuated tubes,

• CPC mirrors, and• collecting box with heat transfer unit.

The evacuated tube

The evacuated tube is a product that is optimized in geometry and performance.

The tubes are composed of two concentric glass tubes which in each case are half spherically closed on one

side and fused together on the other side. The gap between the tubes is evacuated and afterwards hermetically

plugged (vacuum insulation).

In order to make solar power usable, the internal glass tube is provided on its external surface with an

environmentally friendly, highly selective layer and thus designed as an absorber. This coating is thus protected

within the vacuum gap. It is an aluminum nitrite sputter layer which is characterized by very low emission and

very good absorption.

Copper tube

Heat guide plate

Absorber layer

Evacuated tube

CPC mirror





The CPC mirror

In order to increase the efficiency of the evacuated tubes, a highly reflecting, weather-proof CPC mirror

(Compound Parabolic Concentrator) is placed behind the evacuated tubes. The special mirror geometry ensures

that even at unfavorable irradiation angles direct and diffuse sunlight falls onto the absorber. This substantially

improves the energy yield of a solar collector. Unfavorable irradiation angles are given at diagonally incoming light

(azimuth angle) (no south adjustment of the mounting area, sun progress from east to west, diffuse irradiation).

e.g. direct sun exposure

e.g. diagonal, direct sun exposure

e.g. diffuse sun exposure





Collecting box and heat transfer unit

The insulated collecting and distribution pipes are located inside the collecting box.

The advance or return connection can take place alternatively on the left of or on the right.

In each evacuated tube there is a U pipe with direct flow-through that is connected in such a way to the

collecting or distribution pipe that each individual evacuated tube exhibits the same hydraulic resistance.

This U pipe is pressed to the inside of the evacuated tube with the heat guide plate.

U pipe CPC mirror

Collecting box Advance or return

connection

Thermal insulation

Heat guide plate

Collecting pipe /

distribution pipeSensor dipping

sleeve

Evacuated tube




4Technical data

4. Technical data

4.1 Technical specifications for CPC 6/12/18 OEM / INOX

Series CPC 6 OEM / INOX CPC 12 OEM / INOX CPC 18 OEM / INOX

Number of evacuated tubes 6 12 18

η0 (Aperture area), DIN 4757-4 or EN 12975 % 64.2 64.2 64.2

c1 with wind, in relation to aperture area W/( m2k ) 0.89 0.89 0.89

c2 with wind, in relation to aperture area W/( m2k2 ) 0.001 0.001 0.001

Kθ,trans (50°), in relation to aperture area 1 1 1

Kθ,long (50°), in relation to aperture area 0.9 0.9 0.9

yield forecast kWh/m2a 589 589 589

grid measurements

(length, height, depth) m 0.70 x 1.64 x 0.1 1.39 x 1.64 x 0.1 2.08 x 1.64 x 0.1

gross area m2 1.14 2.28 3.41

aperture area m2 1.0 2.0 3.0

absorber capacity - OEM l 0.8 1.6 2.4

absorber capacity - INOX l 0.9 1.8 2.6

weight - OEM kg 19 37 54

weight - INOX kg 19 35 52

max. working pressure burden bar 10 10 10

max. stagnation temperature °C 295 295 295

connection diameter of inlet and

outlet tube mm 15 15 15

material of collector - OEM Al / Cu / glass / silicone / PBT / EPDM / TE

material of collector - INOX Al / Stainless steel / glass / silicone / PBT / EPDM / TE

material of glass tube borosilicate glass 3.3

material of selective absorber coating aluminium nitrite

glass tube (outside and inside thickness/

wall thickness/length of tube) mm 47/37/1.6/1500

colour OEM ( aluminium frame profile, Anodised) aluminium grey

colour INOX (aluminium frame profile,

powder-coated) RAL 7015

colour (plastic parts) black

thermal shock test ITW test number 02COL282

impact-from-hail test

according to DIN EN 12975-2 TÜV test number 435/142448

EC prototype test TÜV test number P-DDK-MUC-04-100029919-014

DIN CERTO registration number 011-75113R and 001-75134R

Heat transfer medium Tyfocor LS




4Technical data

4.2 Pressure drop

Pressure drop of the tube collectors CPC 6/12/18 OEM

Heat distribution medium: Tyfocor LS, medium temperature 40° C

Pressure drop of the tube collectors CPC 6/12/18 INOX

Heat distribution medium: Tyfocor LS, medium temperature 40° C

Flow rate [l/min]

P r e s s u r e d r o p [ m b a r ]

0

20

40

60

80

100

120

0 0,25 0,5 0,75 1 1,25 1,5 1,75 2 2,25 2,5 2,75 3 3,25 3,5 3,75 4 4,25 4,5 4,75 5

CPC 18 OEM

CPC 12 OEM

CPC 6 OEM

Flow rate [l/min]

P r e s s u r e d r o p [ m b a r ]

0

20

40

60

80

100

120

0 0,25 0,5 0,75 1 1,25 1,5 1,75 2 2,25 2,5 2,75 3 3,25 3,5 3,75 4 4,25 4,5 4,75 5

CPC 18 INOX

CPC 12 INOX

CPC 6 INOX



5. Heat output

The collector output is dependent on the efficiency of the collector ( ) as well as the irradiation intensity (G*)

and aperture surface per collector module (A). This determines the thermal energy output of the collector for a

given irradiation intensity. The following equation may be used to calculate the collector output:

whereby:

If the difference between the collector and ambient temperature ( ) is zero, there are no thermal losses

from the collector to the environment and the efficiency is at its maximum; this is referred to as the optical

efficiency .

A proportion of the solar irradiation (G*) on the collectors is "lost" due to reflection and absorption.

The optical efficiency takes these losses into account.

Heating of the collectors will cause them to transfer heat to the environment through conduction, radation and

convection. Heat transmission coefficients a1 and a2 take these losses into account.

The output curves are virtually horizontal. This means that CPC collectors in contrast with flat plate collectors

can still have a high output even when there is a large temperature difference between the collector and the

environment.

Power curve for evacuated tube collectors CPC 6/12 /18 OEM / INOX

at an irradiation G* of 1000 W/m2


5Heat output

C o l l e c t o r o u t p u t p e r m o d u l e [ W ] Power curve

0

500

1.000

1.500

2.000

2.500

0 20 40 60 80 100

CPC 18

CPC 12

CPC 6

][ K )(am

ϑϑ −




5Heat output

Solar irradiation values are low during the winter season and transitional periods (water heating as well as heating

support) (e.g. 400 W/m2 ). The temperature difference between the collector and the environment is also very high

due to the low outdoor temperatures.

The following tables (source: ITW test report no. 06COL513) precisely depict how the collector output varies

depending on the irradiation intensity and temperature difference. The stated values are for vertical irradiation

angles.

Collector output per module [W] for CPC 6 OEM / INOX

Irradiation intensity

400 W/m2 700 W/m2 1,000 W/m2

0 295 517 738

10 285 507 728

30 264 485 707

50 242 463 685



400 W/m2 700 W/m2 1,000 W/m2

0 586 1,025 1,464

10 565 1,004 1,443

30 523 962 1,401

50 479 918 1,357



400 W/m2 700 W/m2 1,000 W/m2

0 768 1,344 1,920

10 741 1,317 1,893

30 686 1,262 1,838

50 628 1,204 1,780




6Configuration of the collector area

6. Configuration of the collector area

For the accurate design of a solar plant, the following parameters must mandatory be known:

• for solar plants for water heating: warm water requirements, user behavior, consumption profile, etc.

• for solar plants supportive of heating, additionally: heat requirements, heating surface design temperatures, etc.

In the majority of all cases, these are not fully known.

Therefore, the specifications in the following 2 tables are to be regarded as recommended approximate values

which in individual cases may be exceeded or fallen below by up to 25%, depending upon customer request

(comfort, costs).

Furthermore, the specifications were based upon the assumption of an approximate adjustment of the collector

field towards the south and a roof pitch between 25° and 50° at the location of Würzburg, Germany.

With deviating boundary conditions, a detailed design with simulation programs is recommended.

Approximate values for the design of collector area (aperture) and reservoir capacity

in home building, or for the design of collector areas for swimming pools(reference location: Würzburg, Germany)

Pure water heating Water heating and part-solar heating

Persons Recommended Recommended Recommended Recommended

aperture area [m2] reservoir capacity [l] aperture area [m2] reservoir capacity [l]

1 2.0 160 3.0 240

2 3.0 240 5.0 400

3 4.0 320 7.0 560

4 5.0 400 9.0 720

5 6.0 480 11.0 8806 7.0 560 13.0 1,040

7 8.0 640 15.0 1,200

8 9.0 720 17.0 1,360

9 10.0 800 19.0 1,520

10 11.0 880 21.0 1,680

11 12.0 960 23.0 1,840

12 13.0 1,040 25.0 2,000

13 14.0 1,120 27.0 2,160

Swimming pool heating

Indoor swimming pool, 24° C Outdoor swimming pool, 24° C

with cover without cover with cover without cover

(m2 aperture area/ (m2 aperture area/ (m2 aperture area/ (m2 aperture area/

m2 basin surface) m2 basin surface) m2 basin surface) m2 basin surface)

0.2 0.3 0.4 0.5

With low warm water requirement, the approximate values may be lowered by up to 25%.

With high warm water requirement, the approximate values may be exceeded by up to 25%.




6Configuration of the collector area

Correction factors

The following two tables are used to correct the collector area in relation to the main usage period,

collector incline and angular deviation from due south.

Strongly recommended

Recommended

Limited recommended

Not recommended

We recommend the use of simulation programs when designing and determining the collector area for

sports facilities, hotels and apartment buildings.




7Notes on solar controllers

7. Notes on solar controllers

Solar controllers for evacuated tube collector systems should include a "boost function". This "boost function"

prevents an excessively high temperature difference between the temperature measured by the collector sensor

and the temperature in the lower/centre part of the pipes. When the collector sensor recognises a temperaturerise, the "boosting" (switching on) of the pump should occur two to three times per minute for ca. 3-5 seconds

to feed the hot solar fluid to the measurement point.




8Configuration of the collector connecting pipes

8. Configuration of the collector connecting pipes

For the dimensioning of the pipes, a medium throughput of approx. 30 - 40 l/h m2 aperture area

(approx. 0.5 - 0.7 l/min m2 ) can be assumed. In particular with large solar plants, we recommend „low-flow“

operation where the specific flow rate can be reduced to approx.12 - 18 l/h m2

(approx. 0.2 - 0.3 l/min m2

).For the reduction of the pipe work requirements, we recommend a series connection of max. 9.0 m2 (high-flow)

and 14 m2 (low-flow) collector aperture area.

In order to keep the pressure drop due to the pipe system of the solar plants as low as possible, the flow velocity

in the copper pipe should not exceed 1 m/s. We recommend flow velocities between 0.3 and 0.5 m/s. The cross

sections are to be dimensioned as with conventional heating equipment according to throughput and speed.

For the installation of the collectors we recommend commercially available normal copper pipe and gunmetal

fittings. Due to the high standstill temperatures, the junction points of the pipe lines should be hard soldered or

connected with clamping ring screw connections.

Galvanized pipes, galvanized pipe fittings, and graphitized gaskets should not be used. Hemp is to be used only

in connection with pressure and temperature resistant sealant. All components used must be resistant against

the heat distribution medium.

The thermal insulation of pipe lines in external areas must be temperature and UV radiation resistant as well as

resistant against bird pecking.

Approximate values for the dimensioning of the pipe diameter

(for series connection of the collectors)

High-flow

Aperture area m2 2 3 4 5 6 7 8 9

Flow rate Liter/min 1.5 2.5 3 3.5 3.5 4 4 4.5

Copper tube Dimensions 12 x 1 12 x 1 15 x 1 15 x 1 18 x 1 18 x 1 18 x 1 18 x 1

Low-flow

Aperture area m2 2 3 4 5 6 7 8 9

Flow rate Liter/min 0.5 1 1 1.5 1.5 1.5 2 2

Copper tube Dimensions 12 x 1 12 x 1 12 x 1 12 x 1 18 x 1 12 x 1 15 x 1 15 x 1

Aperture area m2 10 11 12 13 14 15

Flow rate Liter/min 2.5 2.5 2.5 3 3 3.5

Copper tube Dimensions 15 x 1 15 x 1 15 x 1 15 x 1 18 x 1 18 x 1

The specifications of the pipe diameters refer to a maximum total pipe line lengthof 2 x 20 m Cu pipe and an

average pressure drop of the heat exchanger in the reservoir.

The specifications are reference values which in individual cases should be accurately determined.




9Configuration of the expansion vessel size

9. Configuration of the expansion vessel size

Design fundamentals for the determination of the expansion vessel size

The following formulas as indicated are based on a safety valve of 6 bar. For the accurate calculation of the

expansion vessel size, first the volume contents of the following components must be determined in order toafterwards be able to calculate the vessel size with the following formula.

Formula: V nominal (V unit · 0.1 + V vapor · 1.25) · 4.8

Vnominal = nominal size of the expansion vessel

Vunit = contents of the total solar circuit

Vvapor = contents of the collectors and pipe lines that are situated in the vapor area

Example for the determination of the individual volumes:

Specification: 2 collectors CPC 12 OEM / INOXPipe line: Cu 15 mm, 2 x 15 m length

Static height H: 9 m

Contents of the reservoir heat exchanger and the solar station: e.g., 6.4 l

Pipe lines within the vapor area: Cu pipe 15 mm, 2 x 2 m

You can determine the individual contents of the equipment components from the respective data tables of the

product description. On the following page, the contents of the usual sizes of Cu pipe lines and contents of the

CPC tube collectors are indicated.

Vunit = contents of: Heat exchanger of the reservoir + pipe lines + collectors

= 6.4 l + 30 m · 0.133 l/m + 2 · 1.6 l = 13.59 l

Pipe lines above or on the same level of the collector collecting box (with several collectors one above the other,

the lowest collecting box applies) can be filled with vapor during standstill of the solar plant. Thus, the contents

of the concerned pipe lines and of the collectors are comprised in the steam volume Vvapor.

Vvapor = 2 · 1.6 l + 4 m · 0.133 l/m = 3.73 l

(contents of 2 x CPC 12 OEM / INOX + 4 m pipe Cu 15 mm)

Calculation of the expansion vessel size:

Vnominal (Vunit · 0.1 + Vvapor · 1.25) · 4.8

Vnominal (13.59 l · 0.1 + 3.73 l · 1.25) · 4.8 = 28.90 l

Selected expansion vessel: 35 l

Determination of contents of the unit, primary pressure, and operating pressure:

For the determination of the required amount of solar fluid, the feed of the corresponding expansion vessel must

be added to the unit contents.

The feed in the expansion vessel results from filling the solar plant from the primary pressure to the operating

pressure (dependent on the static height „H“). The following table shows the percentage of the feed, based the

selected vessel nominal size, and the pressure specifications.

With a static height of 9 m, the following applies (see table on the following page):

Vfeed = Vnominal · 12.5 % = 35 l · 0.125 = 4.4 l




9Configuration of the expansion vessel size

Required amount of solar fluid Vtotal:

Vtotal = Vunit + Vfeed = 13.59 l + 4.4 l = 17.99 l

Result:Expansion vessel with 35 l is sufficient, primary pressure 2.5 bar,

operating pressure 3.0 bar, contents of solar fluid 17.99 l.

Static height H Feed in the Primary pressure Operating pressure

between highest expansion vessel

point of the unit and in % of the

expansion vessel GG vessel nominal size

0... 5 m 14.0 % 2.0 bar 2.5 bar

5...10 m 12.5 % 2.5 bar 3.0 bar

10...15 m 11.0 % 3.0 bar 3.5 bar15...20 m 10.0 % 3.5 bar 4.0 bar

Contents of solar components

Copper tube

Type Cu12 Cu15 Cu18 Cu22 Cu28

Content in l/m 0.079 0.133 0.201 0.314 0.491

CollectorsType CPC 6 OEM CPC 12 OEM CPC 18 OEM CPC 6 INOX CPC 12 INOX CPC 18 INOX

Content in l 0.8 1.6 2.4 0.9 1.8 2.6

H



10. Connection possibilities

Connection possibilities for 1 collectorNote: Feeler position on the advance side (hot)

Connection possibilities for 2 or more collectors next to each other

Note: Feeler position on the advance side (hot)

Connection possibilities for 2 or more collectors one above the other

Note: Feeler position on the advance side (hot)


10Connection possibilities

Reverse connection of the

flow direction is possible.




10Connection possibilities

Connection possibilities for 1 or 2 collectors next to each other

and 2 or 3 collectors one above the otherNote: Feeler position on the advance side (hot)

Connection possibilities for 1 or 2 series connections next to each other

and several series connections one above the otherNote: Feeler position on the advance side (hot)

Note: A stop ball valve should be

fitted in each outlet for better

bleeding and balancing of the

collector fields.










12 Assembly instructions

12.3 Weight and placement of the concrete plates with flat roofs

CPC 6 OEM / INOX CPC 12 OEM / INOX CPC 18 OEM / INOX Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim. Dim.

A B B C C A B B C C A B B C C

30° 45° 30° 45° 30° 45° 30° 45° 30° 45° 30° 45°

(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm)

550 1050 810 350 270 1100 1050 810 350 270 1400 1050 810 350 270

Building height up to 8 m

Collector type Number of Angle of Necessary weight of Necessary weight of

angle frames the frame the front concrete plate the rear concrete plate

CPC 6 OEM / INOX 2 30° 75 kg 75 kg






Building height up to 20 m

Collector type Number of Angle of Necessary weight of Necessary weight ofangle frames the frame the front concrete plate the rear concrete plate

CPC 6 OEM / INOX 2 30° 112 kg 112 kg

CPC 12 OEM / INOX 2 30° 112 kg 112 kg

CPC 18 OEM / INOX 2 30° 112 kg 112 kg

CPC 6 OEM / INOX 2 45° 112 kg 112 kg

CPC 12 OEM / INOX 2 45° 112 kg 112 kg

CPC 18 OEM / INOX 2 45° 112 kg 112 kg

Note:

Flat roofs with flint pouring:

Free laying space for concrete

plates from gravel. Flat roofs with plastic sheet

roofing: Lay concrete plates

on protection cover (building

protection mats pos. 1).

Align concrete plates in accordance

with the accompanying illustration.

A BC

C



12.4 Space requirement with perpendicular façade assembly

Space requirement for a single-row collector field:


Number of collectors Dim. A (m) Dim. B (m) Dim. A (m) Dim. B (m) Dim. A (m) Dim. B (m)

1 0.70 1.64 1.40 1.64 2.10 1.64

2 1.40 1.64 2.80 1.64 4.20 1.64

3 2.15 1.64 4.20 1.64 6.30 1.64

4 2.85 1.64 5.60 1.64 8.35 1.64

5 3.55 1.64 7.00 1.64 10.45 1.64

6 4.25 1.64 8.40 1.64 12.55 1.64

Space requirement for a dual-row collector field:


Number of collectors Dim. A (m) Dim. B (m) Dim. A (m) Dim. B (m) Dim. A (m) Dim. B (m)

2 0.70 3.35 1.40 3.35 2.10 3.35

4 1.40 3.35 2.80 3.35 4.20 3.35

6 2.15 3.35 4.20 3.35 6.30 3.35

8 2.85 3.35 5.60 3.35 8.35 3.35

10 3.55 3.35 7.00 3.35 10.45 3.35

12 4.25 3.35 8.40 3.35 12.55 3.35


12 Assembly instructions

B

A










13Certificate Solar Keymark

13. Certificate Solar Keymark



13Certificate Solar Keymark

Documents

Ritter Solar GmbH & Co. KG