beausoleil

Solar update October 20, 2000

Our solar system came online earlier this month during glorious sunny weather here in San Francisco.  We were actually excited to see the clouds come in this past Saturday and then thick fog on Sunday to see how the system fared in less than ideal weather.  These charts come from our SolarCity montoring site and measure output in kilowatt hours over time in half hour increments. Peak power output tends to be around 1pm this time of the year.

October 16, 2008 - Sunny all day - beautiful curve perfectly showing the movement of the sun across the sky.  Total output for the day 13.55 kwH.

October 18, 2008 -Partly cloudy/partly sunny - clouds were in and out, therefore the energy output is much more sporadic.  An interesting note is that the peak power output, 1.13 kwH at 1:30 pm is higher that the maximum output above of 1.07 kwH.  Perhaps the cooler temperatures allowed for greater efficiency? Total output for the day 10.07kwH

October 19, 2008 - Thick fog all day - sad...total output 2.47 kwH

Though the system obviously does not fare as well under thick fog, we have already generated 272 kwH in these three weeks, and are negative 45 kilowatts of peak power use.  Our total power use is still averaging less than 6 kilowatts per day, which is less than 1/4 of our use of October 2007.  We have also offset 309 pounds of CO2 gas in these 3 weeks!  We were told by SolarCity that even with our fog, over the course of a year our system would generate approximately 80% of what a similarly sized system would generate in a sunny neighborhood with similar temperatures.  We will continue to gather data over the next year to compare and analyze for ourselves.

The full data for the week can be found on this spreadsheet. Download beausoleil_solar_data10.19.08.xls

Beausoleil really is solar powered!

As of 9:30am on September 29th our photovoltaic system was up and running (whistles, gongs, chimes!).  PG&E came by to inspect and install our new time-of-use meter, all of which took about ten minutes.  The meter gives a whole slew of data points -- power use at different times of day (corresponding to different rate tiers), power coming in from the p.v. system, power coming in from the grid, net use, etc., so we can monitor the situation. I have to avoid the temptation to check every hour. As of this morning, we have generated close to 145 kwH of power in those 11 days.

In order to analyze the efficiency of our system, particularly with our variably foggy climate in this part of San Francisco, we have set up a spreadsheet with the goal to collect data four times a day.  We will be keeping track of  weather, an instant reading of power generated, a total of the power generated for the day, as well as our power use figures based on PG&E's tiered rate schedule.  For this week's figures, see the attached file.  Download beausoleil_solar_data.xls

Our system has been sized to offset our peak time power use, in the afternoons, and so far our meter has consistently been running backwards during this time of day, even on October 6th, the rainy/foggy day last week.  To date we are negative 17 kwH of peak power use.

Our average power use in October of last year was 25 kwH per day.  Since our system was turned on, thanks to the offset of our solar system, and thanks to more vigilant kids turning out lights in unoccupied rooms, we have used a total of 62 kwH, an average of 5.6 kwH per day.  We will let you know the comparative difference on our PG&E bill when it comes in!