helping you get started with green energy.
A brief comment for discussion only: "sunway's sleek frameless solar panel"
"sunway's sleek frameless solar panel"
http://blog.gogreensolar.com/2009/06/sunways-sleek-frameless-solar-...
A brief comment for discussion only. Since the average systems size for residential would be approximately 4kW. Let's configure a residential systems using the Sunways, modules. The Sunways modules does not yet appear in the string sizing tools. Typically the reason for this would be the module would not yet be Underwriters Laboratories (UL) listed. So let's configure a system manually without the string sizers. Let configure a mid-size ground-mounted array with the Sunways modules. The module has a V(oc) at Open-circuit voltage V(oc) 36.9V. If we choose an SMA - 240V the maximum DC input voltage would be < 600V DCand we configure the string - panel - for a total of 14 modules. Therefore, 14 * 36.9V * 1.14 = ~588V (oc) for a lowest ambient temperature of approximately 14 degrees F in accordance to Table 690.7. Which results in a maximum voltage of < 600 V in the coldest temperature.
But if 2008 NEC, then "When open-circuit voltage temperature coefficients are supplied in the instructions for listed PV modules, they shall be used to calculate the maximum photovoltaic system voltage as required by 110.3(B) instead of using Table 690.7." The California Electrical Code 2007 uses NEC 2005. Nonetheless, let's calculate and use as a FPN to NEC 2005. As a result, the NEC 690.7 was used. But let's calculate in accordance to NEC 2008. The open-circuit voltage temperature coefficients would be Temperature coefficient (% / K) -0.37% There is a typographical error in the Technical Data and think it should be "V"(oc). The V(oc) would be 36.9V to be adjusted, for instance 14 degrees F or -10 degrees C which is approximately 35 degrees C from STC of 25 degrees C. At -0.37% * 35 = -12.95% from V(oc). Since as the temperature decreases, then voltage increase would be 36.9V * 12.95% would be an increase of 4.77V from V(oc) at STC would be 4.77V + 36.9V would be ~ 41.7V * 14 modules would be ~583 V(oc).
In both situations, 15 modules at 14 degrees F would be > 600V DC. However, if the ambient temperature were lowered to 5 degrees F would be a factor of 1.16 = ~599.24 V(oc) in accordance with 2005 NEC, and if 2008 NEC, then temperate change would be 40 degrees C. -0.37% * 40 = 14.8% = ~5.46 V + 36.9V = ~ 42.4 * 14 = 593 V(oc).
Therefore, 14 modules per photovoltaics source circuits - panels would be 2 panels * 14 modules would be 28 modules which is divisible by 4 for aesthetics - @ 4 modules per column. Based in the inverter efficiency curve would select and inverter base on 6580 STC Watts and the NOCT. Would not suggest decreasing the photovoltaic source circuits, with regards to Light Induced Degradation (LID) over time, and for hot climates. With a Temperature coefficient P(mp) (% / K) -0.48%, depending on the specific situation, a ground mounted array may have a INOCT cooler relative to the roof mounted array.
If the systems were available today, use Sunways Solar Module SM 215L at approximately $45,000 installed. As a result, would be 14 piers for 28 modules at 7 columns. The modules would be mounted landscape as the preference to reduce the maximum array height < 7 feet with regards to residential ordinances. Module size : (L x W x D) 1674 mm x 984 mm x 5 mm => The length of an array would be ~ 40 feet long and ~12 feet or less with the tilt at approximately 30 degrees. Although the setback, may be less, allowing for 10 feet on either side of the array and and 10 feet on the front and back, if California, would be 1920 square feet. Since, 70% of the yard area would remain free the requirements would be for, for instance, a backyard of approximately 6400 square feet.
Since there an area should remain free, then the distance from the array to the point of connection is another calculation based on NEC Chapter 9 Table 8 which has Conductor Properties for a Direct-Current Resistance at 75°C (167°F). Thee conduits would be underground in accordance to NEC 300.5 When the conductor temperature decreases, the resistance decreases and the power increase as I(mp) **2 * (R) resistance based on the distance and the NEC at ohm/ kFT for coated cable at stranding of 7. If the array is located at the far corner from the point of connect where the AC < DC distance and the inverter is at the point of connection in accordance with NEC 690.64 (B) and the voltage drop would be < 1% in accordance "ANSI-A range (nominal +5%, nominal, nominal -5%)" also by reducing the voltage drop the power increases for the AC side. On the DC side, let keep the power loss to ~2.5% and the voltage drop < 2% - may be agricultural building or < 3% branch circuits, feeders ... as an FPN to the NEC. Instead of locating the array and then measuring and calculating the conductors, let's determine the distance on let's say a #10AWG. There are other calculations based on NEC Table 310.16, 310.17, to minimize conductor size along with calculations for 75 degree C terminal, but increase power loss.
A #10AWG would be 1.29 ohm/ kFT. At a < 2.5% power loss 3290 watts STC would be, approximately 65 watts. 65 watts = I(mp)**2 * resistance. where I(mp) would be 8.03A => 65 watts/65 . With 2 photovoltaic source circuits - panels would be approximately < ~ 375 feet from the inverter. However, would locate the array much closer to the array to reduce power loss. With the modules in series reduces voltage drop and increases the distance from the inverter. If the modules were in parallel the power loss would increase as the square of the current at maximum power point (Mpp). For ground-mounted arrays NEC 690.5 "Exception No. 1: Ground-mounted or pole-mounted photovoltaic arrays with not more than two paralleled source circuits and with all dc source and dc output circuits isolated from buildings shall be permitted without groundfault protection." although, GFP, keeping the number of strings to 2, provided increased distance from the array to the inverter. As a result, best practices would have the inverter near the AC point of connection. Also, if Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable.
Also on the DC side for FPN or administrative calculation for voltage drop at 2% would be NEC Chapter 9 Table 8 as V% * V(mp) * 1000 / 2 (d) * I(mp) => .02 * 14 * 29.3 V(mp) * 1000 / 2 (375 feet) * 8.03 I(mp) = ~ 1.36 ohm/ kFT for a 2% voltage drop. Since, a AWG #12 would be 2.05 ohm/ kFT and a AWG #10 would be 1.29 ohm/ kFT which is less than < 1.36 ohm /k FT.
Simple, a ground-mounted array 2 strings with 14 modules each for 28 modules, looks good too "which is a sleek black frame-less mono-crystalline solar panel " Reducing the leading edge height of the array may improve aesthetics for a ~ 30 degree tilt.
At gogreensolar.com we can talk about these topics immediately, as but one of the reasons why gogreensolar.com with the up-to-date topics to discuss. In addition, the emphasis of grogreensolar.com in small and midsize systems is yet another reason "helping you get started with green energy."
What do you think?
http://blog.gogreensolar.com/2009/06/sunways-sleek-frameless-solar-...
A brief comment for discussion only. Since the average systems size for residential would be approximately 4kW. Let's configure a residential systems using the Sunways, modules. The Sunways modules does not yet appear in the string sizing tools. Typically the reason for this would be the module would not yet be Underwriters Laboratories (UL) listed. So let's configure a system manually without the string sizers. Let configure a mid-size ground-mounted array with the Sunways modules. The module has a V(oc) at Open-circuit voltage V(oc) 36.9V. If we choose an SMA - 240V the maximum DC input voltage would be < 600V DCand we configure the string - panel - for a total of 14 modules. Therefore, 14 * 36.9V * 1.14 = ~588V (oc) for a lowest ambient temperature of approximately 14 degrees F in accordance to Table 690.7. Which results in a maximum voltage of < 600 V in the coldest temperature.
But if 2008 NEC, then "When open-circuit voltage temperature coefficients are supplied in the instructions for listed PV modules, they shall be used to calculate the maximum photovoltaic system voltage as required by 110.3(B) instead of using Table 690.7." The California Electrical Code 2007 uses NEC 2005. Nonetheless, let's calculate and use as a FPN to NEC 2005. As a result, the NEC 690.7 was used. But let's calculate in accordance to NEC 2008. The open-circuit voltage temperature coefficients would be Temperature coefficient (% / K) -0.37% There is a typographical error in the Technical Data and think it should be "V"(oc). The V(oc) would be 36.9V to be adjusted, for instance 14 degrees F or -10 degrees C which is approximately 35 degrees C from STC of 25 degrees C. At -0.37% * 35 = -12.95% from V(oc). Since as the temperature decreases, then voltage increase would be 36.9V * 12.95% would be an increase of 4.77V from V(oc) at STC would be 4.77V + 36.9V would be ~ 41.7V * 14 modules would be ~583 V(oc).
In both situations, 15 modules at 14 degrees F would be > 600V DC. However, if the ambient temperature were lowered to 5 degrees F would be a factor of 1.16 = ~599.24 V(oc) in accordance with 2005 NEC, and if 2008 NEC, then temperate change would be 40 degrees C. -0.37% * 40 = 14.8% = ~5.46 V + 36.9V = ~ 42.4 * 14 = 593 V(oc).
Therefore, 14 modules per photovoltaics source circuits - panels would be 2 panels * 14 modules would be 28 modules which is divisible by 4 for aesthetics - @ 4 modules per column. Based in the inverter efficiency curve would select and inverter base on 6580 STC Watts and the NOCT. Would not suggest decreasing the photovoltaic source circuits, with regards to Light Induced Degradation (LID) over time, and for hot climates. With a Temperature coefficient P(mp) (% / K) -0.48%, depending on the specific situation, a ground mounted array may have a INOCT cooler relative to the roof mounted array.
If the systems were available today, use Sunways Solar Module SM 215L at approximately $45,000 installed. As a result, would be 14 piers for 28 modules at 7 columns. The modules would be mounted landscape as the preference to reduce the maximum array height < 7 feet with regards to residential ordinances. Module size : (L x W x D) 1674 mm x 984 mm x 5 mm => The length of an array would be ~ 40 feet long and ~12 feet or less with the tilt at approximately 30 degrees. Although the setback, may be less, allowing for 10 feet on either side of the array and and 10 feet on the front and back, if California, would be 1920 square feet. Since, 70% of the yard area would remain free the requirements would be for, for instance, a backyard of approximately 6400 square feet.
Since there an area should remain free, then the distance from the array to the point of connection is another calculation based on NEC Chapter 9 Table 8 which has Conductor Properties for a Direct-Current Resistance at 75°C (167°F). Thee conduits would be underground in accordance to NEC 300.5 When the conductor temperature decreases, the resistance decreases and the power increase as I(mp) **2 * (R) resistance based on the distance and the NEC at ohm/ kFT for coated cable at stranding of 7. If the array is located at the far corner from the point of connect where the AC < DC distance and the inverter is at the point of connection in accordance with NEC 690.64 (B) and the voltage drop would be < 1% in accordance "ANSI-A range (nominal +5%, nominal, nominal -5%)" also by reducing the voltage drop the power increases for the AC side. On the DC side, let keep the power loss to ~2.5% and the voltage drop < 2% - may be agricultural building or < 3% branch circuits, feeders ... as an FPN to the NEC. Instead of locating the array and then measuring and calculating the conductors, let's determine the distance on let's say a #10AWG. There are other calculations based on NEC Table 310.16, 310.17, to minimize conductor size along with calculations for 75 degree C terminal, but increase power loss.
A #10AWG would be 1.29 ohm/ kFT. At a < 2.5% power loss 3290 watts STC would be, approximately 65 watts. 65 watts = I(mp)**2 * resistance. where I(mp) would be 8.03A => 65 watts/65 . With 2 photovoltaic source circuits - panels would be approximately < ~ 375 feet from the inverter. However, would locate the array much closer to the array to reduce power loss. With the modules in series reduces voltage drop and increases the distance from the inverter. If the modules were in parallel the power loss would increase as the square of the current at maximum power point (Mpp). For ground-mounted arrays NEC 690.5 "Exception No. 1: Ground-mounted or pole-mounted photovoltaic arrays with not more than two paralleled source circuits and with all dc source and dc output circuits isolated from buildings shall be permitted without groundfault protection." although, GFP, keeping the number of strings to 2, provided increased distance from the array to the inverter. As a result, best practices would have the inverter near the AC point of connection. Also, if Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable.
Also on the DC side for FPN or administrative calculation for voltage drop at 2% would be NEC Chapter 9 Table 8 as V% * V(mp) * 1000 / 2 (d) * I(mp) => .02 * 14 * 29.3 V(mp) * 1000 / 2 (375 feet) * 8.03 I(mp) = ~ 1.36 ohm/ kFT for a 2% voltage drop. Since, a AWG #12 would be 2.05 ohm/ kFT and a AWG #10 would be 1.29 ohm/ kFT which is less than < 1.36 ohm /k FT.
Simple, a ground-mounted array 2 strings with 14 modules each for 28 modules, looks good too "which is a sleek black frame-less mono-crystalline solar panel " Reducing the leading edge height of the array may improve aesthetics for a ~ 30 degree tilt.
At gogreensolar.com we can talk about these topics immediately, as but one of the reasons why gogreensolar.com with the up-to-date topics to discuss. In addition, the emphasis of grogreensolar.com in small and midsize systems is yet another reason "helping you get started with green energy."
What do you think?
Replies to This Discussion
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Permalink Reply by Martin Herzfeld on -
Also for discussion only, would be the situation with micro-inverters, the module does not yet appear on the compatibility list. In the previous example with macro-inverters was DC > AC. In the situation of micro-inverters would be DC < AC. As a result the voltage drop on the AC side would be ~ < 1%. As a result, the number of modules would decrease based on distance. If the number of modules were 14 then distance would be approximately 50 feet from the point of connection with a conductor size of #10AWG. But if the conductor size increased and the number of modules decrease, then approximately 8 modules with #8 AWG would be approximately ~ 375 feet or more from distance equivalent to the point of connection - 240V AC - #10 AWG then ~200 feet or more - 8 modules. Or if 208V, then #10 AWG - 2 panels at 208V, but suggest divisible by 4
A simple micro-inverter ground-mounted array 1 panel with 8 modules, "which is a sleek black frame-less mono-crystalline solar panel " And a multiple 8 modules and the # of panels for the array for the equivalent distance with a #8 AWG. But if equivalent of 14 modules per panel, then would be a total of 28 modules at "" 50 feet from the point of connection at 240V. A larger AC conductor would be recommended. The number Maximum number of inverters per 15 amp branch circuit would be indicated on the label inverter. Also, suggest reducing the leading edge height of the array may improve aesthetics for a ~ 30 degree tilt.
Any thoughts?
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Permalink Reply by Martin Herzfeld on
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Discussion about comparison of micro-inverter and macro-inverters of ground-mounted arrays:
Although there are distance and voltage drop on the AC side ~<1% results in larger conductors => AC > DC side. Where traditional inverters where the distance would DC > AC. Ground mounted structures for enphase would be for example 8 modules at a distance of ~200 feet from the point of connection NEC 690.64 (B) for a #10 AWG or a #8 for ~400 feet. And for 12 modules would be approximately 100 feet with a #8 AWG. As a result the differentiators may be between roof and ground mounted structure in the requirements for the design. In addition, with regards to the issues with NEC 690.47, may be one, two, or three grounding electrodes. Aware there are some discussions on 2008 690.47. Since the equipment ground ing conductors and system ground ed conductor may be a #8 AWG or a #6 AWG based on NEC 690.46 and NEC 250.120(C).
Also for ground mounted arrays, for instance NEC 110.26, 110.27 would be applicable. In addition, the other guidelines suggesting for ground-mounted array a "clear brush area of ten feet (10')" in California.
In comparison of micro-inverters and traditional inverters would detail discussion would be with regards to readily accessibility:
* If inverter not readily accessible AC, then 2008 NEC 690.14 Additional Provisions. (D) Utility-Interactive Inverters Mounted in Not-Readily-Accessible Locations. (C) (2) Marking. "Each photovoltaic system disconnecting means shall be permanently marked to identify it as a photovoltaic system disconnect." (C) (1) Location. "The photovoltaic disconnecting means shall be installed at a readily accessible location either on the outside of a building or structure or inside nearest the point of entrance of the system conductors. " (D) (3) "The alternating-current output conductors from the inverter and an additional alternating-current disconnecting means for the inverter shall comply with 690.14(C)(1)."(C) (5) "A photovoltaic disconnecting means shall not be required at the photovoltaic module or array location." For micro-inverters, regards to disconnects - since the DC connector would be the DC disconnect therefore use NEC 690.18.
For macro-or traditional inverters,
* If method not readily accessible DC, then 2008 690.31 Methods Permitted (E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building. "Where direct-current photovoltaic source or output circuits of a utility-interactive inverter from a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, or metal enclosures, from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means. The disconnecting means shall comply with 690.14(A) through (D)."
o And because of 2008 NEC 690.31 "system voltages greater than 30 volts are installed in readily accessible" As a result, would suggest as Article 100 Accessible, Readily (Readily Accessible) would be "ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth." would suggest a height of the pole by an elevation of 2.5 m (8 ft) and secure and support in accordance with NEC® 338.10(4)(b) Uses Permitted. Exterior Installations "supported in accordance with NEC® 334.30 for Securing and Supporting." "support shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings designed and installed so as not to damage the cable, at intervals not exceeding 1.4 m (41/2 ft) and within 300 mm (12 in.) of every outlet box."
Applicable would be NEC 90.4 :) What's your thinking?
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Permalink Reply by Martin Herzfeld on
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Also for discussion only would be with regards to tilt which would be based on latitude and for instance ~ 30 degrees other factors.
Resource: http://www.the-electrician.net/pv.htm
Or for the states, the maximum annual receivable radiation for the states would be on page 48 and the effects of array orientation of Photovoltaic Systems for the states at approximately ~ 30 degrees.
Resource: http://www.go2atp.com/Photovoltaic_Systems_P374C26.cfm
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Permalink Reply by Martin Herzfeld on
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"Voltage Drop Considerations" | "Circuit Calculations - Model M190"
http://www.enphaseenergy.com/downloads/EnphaseAppNote_Circuit_Calcu...
http://www.gogreensolar.com/products/enphase-energy-micro-inverter-...
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Permalink Reply by Martin Herzfeld on
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In addition, there are differences in monitoring and information technology solutions of a macro-inverter and micro-inverter systems. And typically the MTBF monitoring < inverter < modules < racks < conductors ?
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Permalink Reply by Deep Patel on -
Martin,
thanks for kicking off this discussion. I think that Sunway's frameless modules are very interesting although Here in N. America the only choice that people have for frameless sleek black modules is FirstSolar, you typically can't buy them direct and the only contractor who offers them are SolarCity. I think many people appreciate the aesthetics of frameless black solar panels, especially homeowners, where aesthetics matter big time, wouldn't you agree?
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Permalink Reply by Martin Herzfeld on
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Deep,
1. One is rare earth and the other reliability:
One is with rare earth materials, ~<20 years MTBF and must be recycled?
One is common earth materials ~> 20 years MTBF and should be recycled?
2. Modules only are blue and black?
3. Both are rectangles with two wires - positive and negative.
4. Both appear not compatible with micro-inverters for interesting artwork creations on the roof or ground.
5. Since Micro-inverters would enable creativity in module placement and array planes surface areas.
What make a solar module look good?
Are "aesthetics are a matter of opinion, one of the most famous equation in mathematics is:" "Euler's equation (pronounced Oilers equation)." Should we transition from big "oilers" to big "Eulers" ? Although and array may be code compliant, does it look? My company, by the way, makes solar look good :) What is the mathematical beauty which should be applied to solar arrays, what color of paint on a home and landscape material improves the look of the array. What time of flowers and other amendments improve the look the array. How does the reducing the leading edge improve the beauty of the array. Are chimneys on homes beautiful? Why are stars beautiful? Is burning coal beautiful? Do you enjoyed seeing the air before you breath it? Can the 'golden ratio' be applied to solar energy systems? Would the development of 'blue' jobs' be artist,landscapers, painters, ... who would make solar energy systems look 'purdy' .... along with colorimetry ?
Would there be a thesis, antithesis, synthesis, emphasis, or an exegesis which explicates construction of solar energy systems?
