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LindaSF
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re: Selecting a solar energy conversion method
LindaSF   4/1/2013 4:14:14 PM
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Your article is a little over my head but from the financial stand point there are 3 points that I always consider when debating between central inverters and micro inverters. Micro inverters are preferred when you need module level monitoring (monitoring the performance of each individual solar module), when partial array shading occurs, or when the design is constrained by locating modules sections of the roof with different orientation. If non of the above are true I usually recommend a central inverter. You can compare prices anywhere online: http://webosolar.com/store/en/80-microinverters

karan91
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re: Selecting a solar energy conversion method
karan91   1/30/2013 10:05:20 AM
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hi,any suggestion Solar Energy Conversion method for solar boat project??

green_is_now
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re: Selecting a solar energy conversion method
green_is_now   1/23/2013 9:51:30 PM
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Large voltage ratio power coversion has lower and lower efficiencies as voltage ratios go up. So its not just IR losses must also consider switching losses with respect to voltage ratio boost levels.

green_is_now
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re: Selecting a solar energy conversion method
green_is_now   1/23/2013 9:49:42 PM
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Also there is no reason the 120 v cant be interleaved to give balanced 220Vac.

green_is_now
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CEO
re: Selecting a solar energy conversion method
green_is_now   1/23/2013 9:49:08 PM
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until the cells get unbalanced and your 1% advatage quickly disapeers and micro inverters win on efficiency for both momentary cell inbalance (think clouds, bird droppings...) Or if a cell degrades or is mismatche power can actually drop in a cell in a series string.

green_is_now
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re: Selecting a solar energy conversion method
green_is_now   1/23/2013 9:44:27 PM
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you misinterpreted him you are both saying the same thing.

HarrisMarcus
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re: Selecting a solar energy conversion method
HarrisMarcus   7/12/2012 5:42:05 PM
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You have stated “As the cell voltage rises, the current in the internal diode rises, leaving less of the photo current for the load”. This is not so. If you follow the panel I-V curve shown in Figure 6 when the cell voltage increases the cell current decreases. The maximum cell voltage is the open circuit voltage, Voc, where the current is zero.

HarrisMarcus
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re: Selecting a solar energy conversion method
HarrisMarcus   7/12/2012 5:38:22 PM
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The maximum power available from the panel does not change but the power that is actually extracted from the panel does change and it is a function of the load resistance RL. This maximum power point occurs when RL = Rs. The boost converter decreases the value of RL by adjusting its duty cycle. The input resistance seen by the panel is RL x (1-du)^2 where du is the duty cycle internally set by the SPV1020. The SPV1020 duty cycle is internally adjusted so that RL x (1-du)^2 equals the panel output resistance Rs.

HarrisMarcus
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re: Selecting a solar energy conversion method
HarrisMarcus   7/12/2012 5:37:19 PM
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RL will normally be much greater than Rs. Interposing the SPV1020 boost converter between the panel and RL decreases the load resistance seen by the panel. The load resistance seen by the panel Rin = RL x (1-du)^2 where du is the duty cycle internally set by SPV1020. The duty cycle is set by the SPV1020 so that RL x (1-du)^2 = Rs, the source resistance of the panel.

HarrisMarcus
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re: Selecting a solar energy conversion method
HarrisMarcus   7/12/2012 5:35:44 PM
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Actually the microinverter method is less efficient than power optimizers and a large central inverter because 1) the voltage is higher and current lower which reduces I square R losses and 2) due to economies of scale there is less overhead and fewer number of components along with control circuits. The efficiency of the SPV1020 power optimizer is 98% and the efficiency of one large central inverter will be more than multiple microinverters.

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