Yeah. Without batteries, are you *sure* you're really going to get the payback you think you are going to get?
Yes.
I am in no way trying to replace my electric company, nor really even supplement it. I am just supplying some of my own electricity so that I don't have to buy it all from CFE. Doing so gets me away from a very punitive rate structure imposed on "heavy" users. I think most people on this bbs would have difficulty avoiding that so-called heavy use group. If your electric bill is running you more than $30 a month (at a typical rate of $0.12 USD per kWh) that would put you into "the dreaded DAC rate" (tm) here and you would pay
at least $112 USD per month.
My planned solar panels
should provide a bit over 220 kWh per month, enough to not only take me out of DAC but put me well into the "basico" subsidized rate. Here's the math:
8 solar panels each rated at 180 watts at maximum output, 1440 watts total.
Annual Insolation Value in Ajijic, Mexico is 6.2, meaning I get the equivalent of 6.2 hours of maximum output during the 12-15 hours of daylight.
System efficiency (adjust for losses through heat, inverter losses, etc.) runs about 81.5%.
Days per month average 30.5. (Very slightly less on non-leap-years
)
(8 * 180 * 6.2 * .815)/1000 = 222 kWh per month.
Cross-check: PVs are about 13% efficient converting sunlight into electricity. On average the earth receives about 1,000 watts of energy per square meter, some places more, some places less. Figure about 1100 here in Ajijic. My solar panels are .8 x 1.6 meters, total area for eight panels is 10.24 M^2. At 13%, they would generate, ummm, let's see...
(8 panels * .8W * 1.6L * 1100 Watts/m^2 * 13% Conversion * 6.2 Insolation * 81.5% Efficiency * 30.5 Days)/1000W/kWh = 226 kWh per month. Close enough.
Those panels probably cannot power the AC at night when you might need it before going to bed..
No, but CFE electric company can. Power outages are rare and usually of short duration, so that isn't a concern. As I said, the primary goal of the PVs is to have to pay CFE less than 150 kWh per month
on a 12-month average. I will go beyond that 150 kWh one or two months out of the year because of the A/C, so I will have to pay CFE 14 cents per kWh for the first 100 kWh over 150, and 36 cents per kWh for anything beyond that. I will have one or two bills in the $100 range each year, the rest of the time in the $10-$12 range. This is low enough annual consumption, even with air conditioning for two months of the year, to keep me well away from the DAC rate, with projected annual savings (compared to DAC) of $1765.
tanstaafl.
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