Peace Corps appropriate community technology/Plumbing a Solar Water Heater

Session 5. Plumbing a Solar Water Heater[edit | edit source]

Total time:	2 hours
Objectives:	To identify plumbing fittings and their uses
	To identify plumbing tools such as pipe wrenches, pipe vise, cutter and threaders
	To demonstrate the mechanisms for galvanized pipe cutting and threading
	To cement PVC (poly vinyl chloride) pipe and fittings together such that no leaks occur
	To diagram a plumbing schematic of a solar water heater
Resources:	Attachment IV-5-A, "Plumbing Fitting Nomenclature"
	Attachment IV-5-B, "Plumbing Schematics Worksheet"
	Attachment IV-5-C, "Plumbing Solar Water Heaters
	Bainbridge, The Integral Passive Solar Water Heater Book
	Anderson, The Solar Home Book, pp. 209-226
	VITA, Village Technology Handbook, pp. 86-91
	Burton, "Integral Passive Solar Water Heater Plans"
Materials:	A variety of plumbing fittings (nipples, elbows, tees, 45's, couplings, unions, lock nuts, adapters, etc.) in 12 and 18 mm (1/2" and 3/4") galvanized iron, and PVC pipes, gate and globe valves, hose clamps, pipe vise, pipe wrenches, pipe cutter, pipe reamer, pipe threader, threading oil, threading compound, PVC solvent, PVC primer

Procedures:

Step 1. (5 minutes)

Present the session objectives and outline the activities.

Step 2. (20 minutes)

Distribute Attachment IV-5-A, "Plumbing Fitting Nomenclature," Spread the assortment of galvanized and PVC plumbing fittings on a large table and have the participants identify and discuss the use of each fitting.

Trainer Notes Allow a few minutes for small groups to assemble five to ten fittings with the understanding that each small group will then name each fitting in the assembly, from end to end, with help from the group as needed. Or, hold up each fitting, piece by piece, and ask the group to name it. Explain that it is important during training to know plumbing terminology or nomenclature in order to: Complete the plumbing schematic worksheet (See Step 6) Complete the solar water heater plumbing schematic and parts list to be developed during the design session Be more clear during construction when one member of the small construction group is sent to get a "1/2" "whatchamacallit" from the shop Better understand any new names for fittings which may exist in the participant's country of assignment Be certain that this step includes a discussion of how and when a pipe union should be used.

Step 3. (15 minutes)

Demonstrate and describe the cutting, reaming and threading of galvanized pipe using the appropriate tools.

Trainer Notes You may choose to ask for volunteers with plumbing experience to demonstrate to the rest of the group how galvanized pipe is cut, reamed and threaded. Be certain that the volunteer is complete in his/her description. Include proper tool use instructions as needed, especially with the cutter, the pipe vise, pipe wrenches, reamer and pipe oil.

Step 4. (10 minutes)

Demonstrate and describe the joining of galvanized pipe using pipe wrenches and pipe joint compound.

Trainer Notes Again, ask for volunteers from the group to demonstrate. Mention the different pipe joint compounds used throughout the world, including oil, oiled rope or twine (China), lead rope, teflon rope, etc. Describe the use of pipe wrenches (i.e., two are needed at one time, how they automatically ratchet, the proper way to hold, adjust, and use a pipe wrench, etc.). Explain that pipe joint compound is placed only on the male threads of the pipe joint so that the compound is evenly spread over the threads as the fitting is tightened.

Step 5. (15 minutes)

Demonstrate and describe the joining of PVC pipe and fittings, using primer and/or solvent.

Trainer Notes Ask for volunteers from the group to demonstrate this step. Point out that: Solvent is placed on the male part only for small size pipe (12 and 18 mm) but for large pipe it is O.K. to use solvent on both ends. If solvent is used on the female end, it may form a bubble and seal off the smaller sized pipes as the two pieces are pressed together. With large pipe, this is less likely to happen. The two pieces need to be twisted together and held still for a few seconds to keep them together. PVC fittings are not re-usable. Describe the process that the solvent goes through to "melt" a thin layer of pipe and fitting together to form the seal. Discuss the usefulness of PVC pipe in solar water heaters, since it cannot take very high temperatures and it doesn't transfer heat well.

Step 6. (20 minutes)

Distribute Attachments IV-5-B and IV-5C and have the participants complete the plumbing schematic of the solar water heater shown in Attachment IV-5-8.

Trainer Notes Allow the participants to work individually or in groups of two to complete the schematic. Explain that the answers are partially described in Attachment IV-5-C. Remind them to label all parts, including pipe size, type, fittings, valves, etc. Remind them of the use of unions in plumbing.

Step 7. (20 minutes)

Have each individual or small group describe and explain their plumbing schematic to the group.

Trainer Notes Be sure the criteria on the worksheet are addressed by each presentation. After the first or second description, ask for any new or different schematics. A. the end of the presentations, briefly identify and discsuss inexpensive and effective plumbing shortcuts: Explain how a tee-with-a-plug can replace a more expensive drain valve at the bottom of each tank. Ask how a mixing valve could be manufactured from scratch, using only one union (one tee, two valves and some nipples).

Step 8. (15 minutes)

Conclude the session with a brief discussion of plumbed vs. unplumbed solar water heaters, their advantages and disadvantages, and their applications in countries in which participants will be serving.

Trainer Notes Allow time at the end of the session for cleanup and dismantling of any plumbing that was constructed during the session.

PLUMBING FITTING NOMENCLATUR

PLUMBING SCHEMATIC WORKSHEET

Directions:

This clinic originally had only cold water at the sink inside. You have just finished building a direct-gain solar water heater 'or the clinic and you need to plumb: (1) cold water to the solar heater and the sink, and (2) hot water to the sink. Use as few parts as necessary to reduce costs. Design a mixing valve to be used at the sink. Use valves and unions where needed. Label all pipe and fitting names and sizes.

PLUMBING SOLAR WATER HEATERS A two-tank, pressurized solar water heater system and A three-tank, pressurized, solar water heater system. A one-tank, non-pressurized solar water with mixing valves and A one-tank, non-pressurized "overflow" solar water heater system.

Session 6. Sizing a Solar Water Heater[edit | edit source]

Total time:	2 hours
Objectives:	To use and discuss the solar water heating sizing formula and sizing rule of thumb
	To review and discuss the relationships between insolation, collector area, storage size and hot water demand
	To correctly orient a solar water heater
	To discuss how to pressure test a plumbing system
Resources:	Attachment IV-6-A, "Rules of Thumb: Sizing a Solar Water Heater"
	Attachment IV-6-8, "Rules of Thumb: Orienting a Solar Water Heater"
	Attachment IV-6-C, "How to Size a Flat Plate Collector"
	Attachment IV-6-D, "How to Pressure Test a Plumbing System"
	Attachment IV-6-E, "Direct Gain Sizing Problems"
	Attachment IV-6-F, "Flat Plate Sizing Problems"
Materials:	Newsprint and felt-tip pens

Trainer Notes This session will require considerable preparation as you will need to make copies of each of the attachments and have them ready for distribution during the session.

Step 1. (5 minutes)

Post the objectives, outline and explain the session activities.

Trainer Notes It is helpful for one or more of the participants to volunteer to describe each attachment to the rest of the group as it is distributed. Encourage group discussion of each attachment and add your comments if the information offered by the volunteer is incomplete or inaccurate. Discuss each of the following questions completely to be certain that every participant understands the principles of each attachment. Encourage those who understand the principles to work with those who are having difficulty.

Step 2. (10 minutes)

Distribute, review and discuss Attachment IV-6-A, "Rules of Thumb: Sizing a Solar Water Hearer."

Trainer Notes To stimulate the discussion: Ask for the difference between a direct gain and a thermosiphon solar water heater. Ask for the sizing ratio of one group's insolation meter. It is appropriate here to explain the difference between a "rule of thumb" and a formula and that the reason for having "rules of thumb" is that they are more easily understood by people with no technical background.

Step 3. (10 minutes)

Distribute, review and discuss Attachment IV-6-B, "Rules of Thumb: Orienting a Solar Water Heater."

Trainer Notes

Since most countries in which the PCVs will serve are within 15° of the equator, it is important that the participants use the sun charts or sun angle calculator from Phase III: Session 2, "The Path of the Sun," to describe the sun's path at or near the equator.

To stimulate and guide the discussion: Ask for the orientation of the tilt of a solar water heater if : 1. You are on the equator, it rains every afternoon, every morning is clear and hot water is needed year-around. 2. You are 15° south of the equator and only need hot water from September through March. 3. You are 15° north of the equator, it rains every morning, the afternoons are clear and you need hot water yeararound.

Step 4. (10 minutes)

Distribute, review and discuss Attachment IV-6-C, "How to Size a Flat Plate Collector."

Trainer Notes Explain that the variables in each step of the attachment can have an effect on the size of the collector needed: if hot water usage doubles, the collector area and tank volume will I have to double. If the number of people using the hot water doubles, then the collector area and storage tank volume will have to double, and so on. Here are some sample discussion questions: Does each variable have a direct relationship to the collector area and storage tank volume (as in the examples I given above) or an inverse relationship to the area and volume (i.e., if the insolation rate mysteriously doubles, the collector area and storage tank volume can be cut in half)? How important is "percent possible sunshine" to the equation? What do you think is the range of collector efficiencies? How can you determine the insolation rate for your own microclimate? Be certain that each participant understands the logic behind the calculations, even if they don't understand the math. Point out that Step 4 of this attachment leaves us with an area-to-volume ratio which is described as a rule of thumb in Attachment IV-6-A.

Step 5. (10 minutes)

Distribute, review and discuss Attachment IV-6-D, "How to Pressure Test a Plumbing System."

Trainer Notes Allow time for everyone to read the attachment. Refer to the last session, Plumbing a Solar Water Heater, and discuss any questions about the attachment.

Step 6. (30 minutes)

Distribute and review Attachment IV-6-E and have the participants complete the problems. When they have finished, have them share and discuss their answers.

Trainer Notes One option during this and other such exercises is to encourage people to work together, in groups of two or three. Although it is not the traditional way of taking a quiz or test, it does promote cooperation end learning and reduces frustration and unnecessary competition for "the best grade." During the discussion of the answers, explain that: Direct gain solar water heaters work best when the desired final temperature is not above 55°C (130°F). Plumbed water heaters should have at least two tanks to reduce mixing of hot and cold water.

Step 7. (30 minutes)

Distribute and review Attachment IV-6-F and have the participants complete the problems. When they have finished, have them share and discuss their answers.

Trainer Notes Remind the participants that they can use either the sizing formula or the sizing rule of thumb in this activity. During the discussion of the answers, note any difference between using the sizing formula and the rule of thumb.

Step 8. (15 minutes)

Conclude the session by reviewing the various methods used to size solar water heaters.

Trainer Notes Explain that the participants will have an opportunity to apply the information from this session during the design and construction of solar water heaters. Encourage any questions, comments or discussion.

RULES OF THUMB: SIZING A SOLAR WATER HEATER

Direct Gain Solar Water Heaters

Direct gain solar water heaters are usually sized at 80 liters of water storage for every square meter of collector aperture or area. This ratio of 80:1 will provide hot water (55°C or 130°F) in the afternoon of sunny, warm days if the tank is filled with cold water (15°C or 60°F) in the morning.

If this ratio is changed to 40 liters of water for every square meter of collector (40:1), then the water will heat up faster but will also cool off faster in the afternoon or at night if the tanks are not insulated.

If this ratio is changed to 120:1, the water will barely get warm (38°C or 100°F) but will retain its heat for many hours. This ratio is best used to pre-heat water which will be heated to a higher degree with another heat source. This is the most cost-effective ratio but provides the least hot water.

Flat Plate Collector Solar Water Heaters

The 80:1 ratio also holds true for flat plate collector solar water heaters. Flat plate collector systems, however, have the advantage that the solar heated water is stored in an insulated container so it is less likely to cool down in the afternoon or at night.

Ratios approaching 40:1 tend to be less cost effective. Since it is the collector that determines the total cost of the system, more collector with less storage will cost more and provide you with less hot water.

Ratios approaching 120:1 are more cost effective but will not heat water as hot as an 80:1 ratio system. A system with a ratio of 120:1 will warm the water most of the year, heat it up very well a few months of the year, but will need to be supplemented with another water heater to get hot water (55°C or 130°F) for most sunny and warm months of the year.

Experimenting

Build a solar water heater or an insolation meter when you get to your country and change the storage tank-to-collector aperture ratio to find which ratio will work best for you in your microclimate.

RULES OF THUMB: ORIENTING A SOLAR WATER HEATER

In North America, a common rule of thumb for orienting a solar water heater is to face it within 45° of true south (with true south being the optimal direction) at a tilt of "latitude plus 10 degrees." The Continental United States includes latitudes from 25° to 48°. Therefore, tilt angles can vary from 35° to nearly 60° from the horizontal.

As solar collectors approach the equator, orientation and tilt become more seasonal because the sun moves into both the north and south hemispheres during the course of the year. There Fore, orientation depends on when the solar energy is needed (which months) and the local microclimate (i.e., are there clear mornings or clear afternoons during the months when the solar energy is needed?). If a solar collector is on the equator and facing south with a tilt of 15° from the horizontal, it will work well during the months of September through March. However, from March until September, the sun will be behind the collector. If a solar collector is facing east with a tilt of 15°, it will collect well only during the morning hours. This orientation is best for locations with cloudy and/or rainy afternoons.

The best tilt for a solar collector on the equator is no tilt at all: a horizontal collector. This causes problems, however, with naturally circulating systems such as food dryers and thermosiphon water heaters: the air or water doesn't know which way to flow; it doesn't know which way is up. As soon as you tilt and orient a collector, it will only work half of the day or year.

Therefore, the tilt and orientation of a solar collector near the equator depends on what time of year the solar energy is needed and what part of the day is sunniest in the microclimate of the collector.

The orientation of a solar collector in the Southern Hemisphere should be toward the north, toward the equator. The tilt of the collector should be the same as for a Northern Hemisphere collector -- latitude plus 10°.

HOW TO SIZE A FLAT PLATE COLLECTOR

To properly design and construct a passive solar water heater, one needs to know the amount of energy required in the form of heated water and the amount of sunlight available on an average day during the time of least sunshine.

By simply dividing the energy required per day by the energy available per day per area, one can determine the area of collector aperture needed.

1. How much energy is required?

Find:

Average hot water usage per person per day

Number of people using hot water per day

Desired temperature of hot water

Incoming cold water temperature

Density of water (weight per volume)

For example:

40 liters hot water per person per day

3 people per day

45 degrees C desired hot water temperature

15 degrees C incoming water temperature

Density of water is 1 Kg/liter (energy required)

1. How much energy is available?

Find:

Clear day winter insolation for the desired tilt

Percent possible sunshine

Collector system efficiency

For example:

2700 Kgcal/m² day

65% possible sunshine

40% system efficiency (energy available)

1. By dividing the amount of energy required (Step 1) by the amount of energy available (Step 2) one can get a very good approximation of the collector aperture required to provide the desired temperature and volume of water on an average day during the period of least sunshine.

For example:5.1 m² of collector aperture is needed to provide 120 liters of water at 45°C if the incoming water is at 15°C and the insolation is 2700 Kgcal/m² day.

(Notice how a complex fraction -- a fraction over a fraction -can be simplified by "inverting and multiplying." Also note how the units will always cross out to leave 2 just the units needed: in this case, square meters, or m .)

1. Once this ratio of aperture-to-volume is found, it can be used to size a collector for any size hot water tank, assuming all of the variables remain the same.

If the system will not be asked to provide hot water during the period of least sunshine (if, for example, there is virtually no sun for six months of the year), the clear day summer isolation for the desired tilt and the summer percent possible sunshine must be substituted for the winter data used in Step 2. Summertime system efficiency is also much greater than wintertime efficiency because there is less heat loss in the summer.

Care must be taken not to ask too much of a solar collector system: If a system is sized to provide hot water in the winter, it will probably produce very hot water in the summer, which is potentially dangerous (scalding occurs at water temperatures of 60 C).

HOW TO PRESSURE TEST A PLUMBING SYSTEM

1. To pressure test with water only:

Cap or plug all openings in the system, except two. Of these two, loosely cap or plug one of them and attach a garden hose or some other water source to the other. Make sure that the loosely capped or plugged opening is near the top of the system.

Begin filling the system. When water begins to leak from the loosely capped or plugged opening, tighten the cap or plug so that no water can escape. Inspect all joints in the system for leaks by looking for obvious ones and feeling each joint for any sign of moisture. Mark any leaky joints. Drain the system, fix the leaks and re-test.

1. To pressure test with water and compressed air:

Cap or plug all but one opening near the top of the system. Fill the system with water using this upper opening. Attach a compressed air source to the system and compress to 50 pounds per square inch (3.5 Kg/cm²) pressure or to the pressure at which the system will be operating, whichever is greater. Tap each joint with a wooden or rubber mallet to simulate expansion and contraction stresses. Look for water leaks at each joint. Mark all leaks, drain the system, repair the leaks and re-test. (If a pressure gauge is available, attach it to the system and test for 24 hours.)

1. To pressure test with air only:

Cap or plug all but one opening of the system. Attach the pressure gauge tester to the remaining opening and compress with air to 50 psi or 3.5 Kg/cm² or the pressure at which the system will be operating, whichever is greater. Tap all joints with a wooden mallet to simulate expansion and contraction stresses. Listen for leaks. Leave the gauge on the system for at least 24 hours. If the gauge shows ANY decrease in pressure, there is a leak in the system. Leaks can be found by applying a soap-and-water solution to each joint and watching for bubble formations. Mark any leaks. Release the pressure from the system, fix the leaks and re-test.

DIRECT CAIN SIZING PROBLEMS

Given the following information, decide whether or not a direct gain solar water heater will be effective and, if so, find the number and size of tanks needed and the aperture needed to raise the water to the desired temperature.

Daily hot water volume requirement (liters)	80	200	240	300	400
Desired outlet temperature (0° C)	50	65	40	45	70
Inlet temperature (0° C)	15	20	20	15	20
Insolation available (Kgcal)/(m² day)	2300	3000	2700	2500	2250
Will a direct gain solar water heater be effective? (Yes / No)
Number and size of tanks
Aperture area (m²)

FLAT PLATE SIZING PROBLEMS

Given the following data, determine the size of storage tank and area of collector required. Assume a 50% efficiency on the collector.

Hot water volume requirement (liters/day)	100	120	40	200	20
Desired hot outlet temperature (0° C)	40	50	55	60	35
Inlet water temperature (0° C)	15	20	15	20	15
Insolation rate (Kgcal)/(M² day)	2700	2500	2000	3000	2250
Percent possible sunshine (%)	75%	70%	65%	60%	50%
Size of tank(s)
Area of flat plate collector (m²)

Session 7. Demonstrating a Technical Concept[edit | edit source]

Total time:	2 hours
Objectives:	To practice explaining, demonstrating and transferring technical information
	To identify and discuss effective communication techniques involved in transferring technical information
Resources:	Attachment IV-7-A, "Role Play Descriptions"
	Fuglesang, Applied Communication in Developing Countries
	Hall, Beyond Culture
Materials:	Newsprint and felt-tip pens, hot plate and tea kettle (or coffee percolator or other steam source), 1m² (1 ft.²) sheet of glass

Trainer Notes This session will require considerable advance planning, study and preparation. You should familiarize yourself well with the procedures before beginning the session. Also, all the role play descriptions from Attachment IV-7-A should be read, cut out and organized for distribution in advance. In this session, there are a total of six role play situations: three in which participants play PCVSs and three in which they play villagers. Each participant will play the PCV role once and the villager role twice. There will be one presentation done by each of the three PCV role play groups. While the first PCV role play group is doing its presentation, all the other participants will play the first villager role described in the attachment (Part II). Then, while the second PCV role play group is doing its presentation, all other participants will role play the second villager role. And, finally, while the third PCV role play group is doing its presentation, all other participants will take the third villager role.

Step 1. (5 minutes)

Briefly present the session objectives and review the procedures.

Step 2. (10 minutes)

Have the participants divide into three groups and distribute the three PCV role play descriptions from Part of the attachment.

Trainer Notes Distribute to each PCV group the "General Role Description." Distribute to PCV role play Group #1 the firs. "Specific Role Description." Distribute to PCV role play Groups #2 and #3 the second and third "Specific Role Descriptions" respectively. Give newsprint and felt-tip pens to PCV Groups #2 and 3#. Give the glass and steam source to PCV Group #3.

Step 3. (25 minutes)

Have each PCV role play group prepare its presentation based on the information provided by the descriptions.

Step 4. (10 minutes)

Reconvene all the participants and ask PCV role Group #1 to set up their presentation as you distribute and explain the First Villager role description (from Part II of the attachment) to all of the other participants.

Explain that while PCV role play Group #1 is doing their presentation, all other participants will be role playing villagers as described in the First Villager role description.

Step 5. (15 minutes)

Have PCV role play Group #1 do their presentation.

Step 6. (5 minutes)

Have PCV role play Group 2# set up their presentation as you distribute and explain the Second Villager role description (from Part 11 or the attachment) to all of the other participants.

Trainer Notes Explain that while PCV role play Group #2 is doing their presentation, all other participants will be role playing villagers as described in the Second villager role description.

Step 7. (15 minutes)

Have PCV role play Group #2 do their presentation.

Step 8. (5 minutes)

Have PCV role play Group #3 set up their presentation as you distribute and explain the Third Villager role description (from Part II of the attachment) to all of the other participants.

Trainer Notes Explain that while PCV role play Group #3 is doing their presentation, all other participants will be role playing villagers as described in the Third Villager role description.

Step 9. (15 minutes)

Have PCV role play Group #3 do their presentation.

Step 10. (15 minutes)

Have all the participants regroup and discuss the effectiveness of each role play presentation.

Trainer Notes Encourage the participants to generalize about effective or ineffective communication techniques used during the presentation. As an aid to discussion, post the following: I hear, I forget; I see, I remember; I do, I understand. -Confucius- Mention that the use of all the senses is the best way to learn.

ROLE PLAY DESCRIPTIONS

Part I: PCV Role Descriptions

General Role Description to be distributed to every member of each PCV role play group.

You are PCVs in a small village in rural Africa where historically a high infant mortality rate has been experienced which has been attributed to amoeboic dysentery caused by unsanitary water. The youngest son of the village chief contracted this disease and recently died.

Concerned villagers, especially the chief, have asked you and your group to discuss ways of solving this problem. Your job, should you choose to accept it, is to explain the concepts of evaporation/ condensation as they apply to solar stills and clean water.

Specific Role Descriptions to be distributed to group members only.

PCV Group #1:	This culture does not- permit use of gestures outside of the immediate family and does not appreciate material from outside of the immediate family nor any material from outside the village used for communication. Therefore, no visual aids or props can be used.
PCV Group #2:	This village has a high degree of appreciation for nonverbal communication based upon designs and figures used in weaving. It is considered impolite for a nonvillager to make speeches. Therefore, you may not as an individual speak more than two sentences at a time. Posters that you have previously drawn showing vectors of fly-borne disease have had a great impact in raising village consciousness.
PCV Group #3:	In the past, this village has had limited exposure to Westerners and ideas of the West, so that there is understanding of visual symbols, pictures, alphabets and advertising. Local crafts are important to village life and skills are taught by elder craftsmen to young boys by apprenticeship. These young boys learn by doing.

ROLE PLAY DESCRIPTIONS

Part II: Villager Role Descriptions

First Villager:	You are concerned about children dying, disapprove of gestures. You have a tradition of listening politely to and being cooperative with strangers. You are a dignified, serious and industrious people.(Distribute to PCV Groups #2 and #3)
Second Villager:	You are concerned about children dying, appreciate visual representations, do not like strangers to talk too much (it is improper for strangers to speak more than two sentences at a time). You have a tradition of listening politely to and being cooperative with strangers. You are a dignified, serious and industrious people. (Distribute to PCV Groups #1 and #3)
Third Villager:	You are concerned about the death of your children. You have little patience with listening to the expression of new ideas. You are anxious to learn by doing. You have a tradition of listening politely to and being cooperative with strangers. You are a dignified, serious and industrious people. (Distribute to PCV Groups #1 and #2)

Session 8. Shade Mapping and Solar Siting[edit | edit source]

Total time:	2 hours
Objectives:	To develop a shade map for solar site
	To determine a good solar site
Resources:	Mazria, The Passive Solar Energy Book, pp. 325-327
	Attachment IV-8-A, "Plotting Azimuth and Altitude"
	Attachment IV-8-8, "Shade Mapping Worksheet"
Materials:	Directional compasses, protractors, string, plumb bobs (such as 12mm nuts, rocks, etc.), newsprint and felt-tip pens

Procedures:

Step 1. (5 minutes)

List the objectives and outline the session activities.

Step 2. (10 minutes)

Distribute Attachments IV-8-A and IV-8-B to each participant and explain them briefly.

Step 3. (40 minutes)

Have the participants form their solar work groups and develop a shade map for a potential solar site as shown in Attachment IV-8-A.

Trainer Notes Distribute one directional compass, protractor, string and plumb bob to each group. Circulate among the groups to see that everyone understands shade mapping. Offer assistance as needed. Be sure each group has its compass set properly, as shown in Attachment IV-8-A.

Step 4. (30 minutes)

Reconvene the groups and analyze the sun charts by having participants share and discuss their findings

Trainer Notes Demonstrate that a shade map can be analyzed by overlaying a sun chart with the shade mapping worksheet (Attachment IV-8B) and looking through them toward a light source, such as the sun. If obstacles show above any of the sun paths, the potential solar site will be shaded at that time of year and that time of day. If the shading is or will be substantial, another site will have to be found. Have each group describe their potential solar site and their analysis of that site. Ask what range of azimuths need to be considered for possible shading problems a. the training site. Ask where the "solar window" is on the sun chart.

Step 5. (20 minutes)

Have the groups develop another shade map.

Trainer Notes Participants can be given the choice of developing a shade map for either a hypothetical site on the equator or a site in the country in which they will be serving. Encourage different people to do the siting and recording so that all of the group members get practice and understand the process.

Step 6. (20 minutes)

Reconvene the groups and discuss the findings.

Trainer Notes Ask what range of azimuths need to be considered on the equator or in the host countries. Explain that the solar sites located by the groups during this session can be used as locations for their solar collectors during the next two phases. Mention that the groups have the option of designing solar collectors for the training site or for their host country (if they're not the same) since the orientation and tilt may be different.

PLOTTING AZIMUTH AND ALTITUDE

Finding azimuth

Step 1

Find the azimuth of the obstacle (tree) by lining up your eye, the center or the compass and the obstacle. Be sure the compass is corrected for magnetic variation. Read the azimuth of the obstacle, 160° in this example.

Step 2

Find the altitude by lining up your eye with the top of the obstacle along the straight edge of the protractor. The plumb bob will register the altitude, 20° in this example.

Step 3

Plot the azimuth (160° from Step 1) and the altitude (20° from Step 2) on the shade mapping worksheet as shown. If the December 21 sun path does not cross the image of the obstacle (tree), the obstacle will not shade the collector at this solar site.

Step 4

Locate all possible obstacles and plot them on the shade mapping worksheet. Analyze the data to determine if the potential solar site is actually a good solar site.

SHADE MAPPING WORKSHEET