{"id":139,"date":"2022-05-12T13:58:23","date_gmt":"2022-05-12T17:58:23","guid":{"rendered":"https:\/\/opentextbc.ca\/plumbing3g\/chapter\/solar-installation-considerations\/"},"modified":"2022-10-03T16:28:51","modified_gmt":"2022-10-03T20:28:51","slug":"solar-installation-considerations","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/plumbing3g\/chapter\/solar-installation-considerations\/","title":{"raw":"Learning Task 4","rendered":"Learning Task 4"},"content":{"raw":"Probably the single most important consideration in a solar system is the placing of the collector(s), with any possibility of shading being the determining factor. Collector arrays located so that they have direct sun playing on them all day long, if it is present, is certainly the situation to strive for. Properly assessing every potential site for possible shading from trees, hills and other objects is extremely critical and can be challenging, given the conditions and time of year that the assessment is being done. Special tools are available that can assist in predicting the possible occurrence of shading at any specific location. One such tool, called a \u201csolar pathfinder\u201d, is shown in Figure 1 below.\r\n\r\n[caption id=\"attachment_138\" align=\"aligncenter\" width=\"400\"]\"\" Figure 1 Solar pathfinder[\/caption]\r\n\r\nThis device is placed at the location being considered. After being properly leveled and oriented according to the local latitude and longitude coordinates, it will use the reflections of nearby obstructions through its clear dome and project them onto a special chart that predicts the shading effects through the entire year. Because direct solar intensity varies throughout the day, some minimal shading in early morning and late afternoon isn\u2019t as critical as it is between the hours of 9am and 3pm, when no shading should be encountered.\r\n\r\nWhile collectors are manufactured to withstand severe weather conditions, if collector arrays are to last as long as the collectors themselves, the installation base they are mounted on must be sound. Collectors can be mounted on roofs (most common) or at ground level, as seen in Figure 2 below.\r\n\r\n[caption id=\"attachment_138\" align=\"aligncenter\" width=\"400\"]\"\" Figure 2 Collector mounting locations[\/caption]\r\n\r\nCollectors mounted on a frame that is affixed to a roof may have little ability to be positioned at the optimum angles for direct solar energy collection, such as seen in the upper picture in Figure 2. A ground-level array, as seen in the lower picture in Figure 27, can be better positioned for energy collection purposes but will take up more space than the roof-mounted array. If collector positioning is critical and ground area is limited, special engineer-designed pedestals can be an option. Figure 3 below shows a solar PV (photovoltaic) pedestal-mounted array that is positioned for optimal solar energy collection.\r\n\r\n[caption id=\"attachment_138\" align=\"aligncenter\" width=\"400\"]\"\" Figure 3 Pedestal-mounted PV array[\/caption]\r\n\r\nThis option raises the array off the ground, allowing for optimum positioning for maximum solar gain while not taking away as much ground area. However, support and protection for the supply and return piping will be more difficult.\r\n\r\nWhile solar collectors should be installed level, all solar piping should be pitched to allow adequate drainage when required, as well as to allow air to be vented through the high point on the top header (if the system isn\u2019t of the drainback variety). Good piping insulation is also critical. A good foam rubber type insulation, without a split feature, is the best choice, although its installation must be done at the time the piping is being joined together. This can make the installation more difficult but certainly not impossible. Fewer gaps in the insulation allows less air movement around the pipes and provides a better insulation level. Weather and birds, such as crows, can wreak havoc on foam insulation and it may require a plastic or aluminum cover to protect it. Ideally all joints in the insulation should be sealed.\r\n

Collector Mounting Angles<\/h1>\r\nIn the northern hemisphere, the optimum azimuth angle (check back to Figure 2) is 180\u00b0, which means the solar array faces directly polar south. Studies have shown that the azimuth angle can vary by as much as 30\u00b0 east or west of polar south without having much effect on the annual solar energy gain. What does have a large effect is the solar collector angle or horizontal \u201ctilt\u201d of the array (again, check back to Figure 2). Studies suggest that collectors used for solar domestic water heating operate best at an angle equal to the local latitude. For space heating purposes, they suggest a solar angle of the local latitude plus 10 to 20\u00b0 to allow better energy collection during late fall, winter and early spring. In order to satisfy both requirements, it is generally acceptable to install collectors at a solar angle of local latitude plus 15\u00b0. For example, an array in Kelowna, with a latitude of 49.8880\u00b0N should be tilted at approximately 65\u00b0 from horizontal and an azimuth angle of polar south. If possible, construction design may be altered to accommodate roof-mounted collectors by increasing roof angles in that area. Figure 4 below shows an array that supplies both space and domestic heating. The roof angle was increased to 60\u00b0 in a geographic location at 44\u00b0N.\r\n\r\n[caption id=\"attachment_138\" align=\"aligncenter\" width=\"400\"]\"\" Figure 4 Roof slope increased to accommodate optimum solar angle for collector array[\/caption]\r\n

Equipment Installation Considerations<\/h1>\r\nSolar equipment in the mechanical room should be carefully arranged so as to provide adequate access for servicing and minimize loss of available space. A neatly arranged, well thought-out placement of equipment and piping will project an air of professionalism and contributes to good aesthetics. Tank size and placement is critical. Space limitations may require the use of multiple smaller tanks rather than one large one. As well, they may have to be small enough to fit through a doorway if replacement is needed. Floors must be constructed strong enough to bear the weight of the full tanks, and ceilings may have to be utilized for the support of horizontal piping and pumps. Labeling of components is important if a service technician has to decipher the layout, and a simply-worded \u201csequence of operation\u201d, which spells out exactly how the system works, should be left in a conspicuous place in the mechanical room. This alone is a huge boon to any service tech.\r\n\r\nAs far as piping materials are concerned, copper is the piping of choice for these systems, and today\u2019s pressing technology is preferred due to the lack of flux and other contaminants such as solder potentially plugging the system. Flushing flux from piping and components with cold water rarely achieves good results, although the flux will thin and coat the inside of the system once the system heats up, but it will still remain there, so pressed fittings alleviate that situation.\r\n\r\nAs with any other fluid mechanical system, solar systems must be tested according to the codes and regulations being adhered to, as well as to manufacturers\u2019 specifications. This should be done with the collector array covered, or at night, to avoid unwanted heat during the process. After testing, the system should be flushed according to good piping practices before it is put into operation, done as well at night or without the collectors absorbing heat. Some literature suggests a flushing solution of 1% to 2% trisodium phosphate (TSP) to aid in the removal of dirt and debris.\r\n\r\nTesting, commissioning and final report checklists are available to assist the technician in ensuring that no important points of these procedures are overlooked.\r\n

Active Solar System Performance Estimates<\/h1>\r\nThere are so many variations of collector types, geographic locations, equipment types, etc. that an estimation of the performance of a solar thermal system will be very difficult for any contractor or installer. Fortunately, software programs exist that can be helpful when proposing an installation to a potential customer. Three of the most common software tools that simulate the performance of a solar system are:\r\n