I've started at least two other threads seeking information about equipment for my DIY project, and people keep warning me of the likelihood that my project is not economically viable. So I'm starting this thread to discuss that subject.
I plan to build a ground-mounted grid-tied system of approximately 5kw. I plan to do all the work myself. I've done quite a bit of carpentry and house wiring (and I am an electrical engineer); my county allows DIY, including electrical work, subject to inspection. I will build a simple wooden structure and use rails from someone like IronRidge for mounting (the structure will be used as semi-dry storage for trash cans, garden tools, etc).
Using PVWatts, with these assumptions: DC size 4.8kw, standard panels with open-rack mounting, all system losses default except shading is 30% (for total losses of 38%), tilt of 30 degrees and azimuth of 172 degrees (slightly sub-optimal, at a cost of about 1/3 of one percent of production), I get 5044 kwh per year. The biggest question mark in this analysis is the figure for shading loss; this is the figure derived by a big installer, who gave me a quote with a guaranteed output using that number); also, I have the ownership and the ability to cut down problem trees.
I'm estimating the cost as follows:
$3145 for 15 Canadian 320 watt panels from (delivered from A1 Solar Store)
$683 for 15 Tigo TS4-R-O optimizers(delivered from altestore)
$1186 for SMA inverter (delivered from Renvu)
$750 materials for structure
$750 mounting rails and hardware ($50 per panel)
$1000 miscellaneous supplies (mostly electrical)
$200 permits
$250 engineering seal for structure
... for a total of $7964, or about $5600 after the federal tax credit.
So the bottom line is $1.10 construction cost per annual kwh of generation.
I'm on a time-of-day rate, with net metering, paying about $0.30/kwh during peak (6-10am winter, 1-6pm summer) and about $0.05/kwh otherwise. In fact, my output will first be credited against my peak usage, and the remainder credited against my off-peak usage; all excess production will be credited at the off-peak rate. I calculate a return of about $368 per year. For a payoff slightly less than 14 years (ignoring the time value of money, and the increase in my house's value). Also, our rural coop will get improved metering equipment in "a few years", at which time excess production during peak hours will be credited at the peak rate.
I plan to build a ground-mounted grid-tied system of approximately 5kw. I plan to do all the work myself. I've done quite a bit of carpentry and house wiring (and I am an electrical engineer); my county allows DIY, including electrical work, subject to inspection. I will build a simple wooden structure and use rails from someone like IronRidge for mounting (the structure will be used as semi-dry storage for trash cans, garden tools, etc).
Using PVWatts, with these assumptions: DC size 4.8kw, standard panels with open-rack mounting, all system losses default except shading is 30% (for total losses of 38%), tilt of 30 degrees and azimuth of 172 degrees (slightly sub-optimal, at a cost of about 1/3 of one percent of production), I get 5044 kwh per year. The biggest question mark in this analysis is the figure for shading loss; this is the figure derived by a big installer, who gave me a quote with a guaranteed output using that number); also, I have the ownership and the ability to cut down problem trees.
I'm estimating the cost as follows:
$3145 for 15 Canadian 320 watt panels from (delivered from A1 Solar Store)
$683 for 15 Tigo TS4-R-O optimizers(delivered from altestore)
$1186 for SMA inverter (delivered from Renvu)
$750 materials for structure
$750 mounting rails and hardware ($50 per panel)
$1000 miscellaneous supplies (mostly electrical)
$200 permits
$250 engineering seal for structure
... for a total of $7964, or about $5600 after the federal tax credit.
So the bottom line is $1.10 construction cost per annual kwh of generation.
I'm on a time-of-day rate, with net metering, paying about $0.30/kwh during peak (6-10am winter, 1-6pm summer) and about $0.05/kwh otherwise. In fact, my output will first be credited against my peak usage, and the remainder credited against my off-peak usage; all excess production will be credited at the off-peak rate. I calculate a return of about $368 per year. For a payoff slightly less than 14 years (ignoring the time value of money, and the increase in my house's value). Also, our rural coop will get improved metering equipment in "a few years", at which time excess production during peak hours will be credited at the peak rate.
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