Cordero Has Gone Solar
On February 9th, 2007 - 4 months ago to the day - we installed photovoltaic panels on the roof of our garage. Sure, we could have put them in the back, but then nobody would know we have them! So, there they sit, high above our two hybrids: my 7-year-old Honda Insight, and Ellen’s new Ford Escape Hybrid:
The goal was to supply half of our electrical needs, reducing our monthly bill by somewhat more because of the tiered billing system in which the more you use, the higher the rate you pay.
How My Utility Charges Me for Electricity
It starts with a baseline - this is the allotment of electricity they will provide me at the cheapest rate. It is determined by a number of factors, including where I live [coastal, inland, etc], my past usage, and average usage across the customer base. Staying within my baseline is smart economically, difficult from a practical standpoint - without solar panels. My utility, San Diego Gas and Electric, charges me 12.4 cents for each baseline kWH I buy from them. But the rates go up quickly: let’s say I use 150% of my a baseline one month. Those last kWH would cost me double: 23.9 cent/kWH.
And this is one of the reasons that going solar makes sense today - it shaves the most expensive kWH off your bill. Even a small installation can frequently get you out of the upper tiers. [The same argument, obviously, works for conservation - fluorescent bulbs, turning things off when not in use, more efficient appliances can all make a disproportionate contribution to reducing your bill due to the tiered rate structure.]
Early Results
So, how has it been working out? Here in Southern California we do get a fair amount of sun; since install we have generated about 19 kWH daily, on average. How much is that? Well, with 5 adults in the house and an electric range and oven for cooking we consume about 32 kWH daily, so it looks like we have accomplished the goal of supplying half of our needs - as of right now we are a little over 60%. Here is what it looks like so far:
The maroon line is a lifetime percentage of our consumption supplied by our panels; as spring edges toward summer it is steadily increasing. The choppier blue line is a 2-week moving average of the same data. You can see that starting in late April the numbers started getting quite a bit better: longer days, higher sun, lower usage of electric space heaters [and we have several]. Notice the dip in the 2-week moving average around May 9? It was hot, hot, hot and we turned on the air conditioning. Killer on the consumption. That day was sufficient motivation to finally get a solar-powered attic fan installed. This should make a big difference in the temps of the upstairs bedrooms on the coming hot, summer days, enabling us to run the A/C a little less.
A few days later - May 12, 13 - we had our first days on which we were net-positive - we generated more than we used. Yippee!
What About the Bottomline?
How about our bill? In January, the last month with no solar generated electricity at all, we paid $177. In February, with about 3 weeks of solar , we were down to about $70 - even though our consumption was almost identical - saving over $90 because of our panels. While we are generating only a little over 50% of our demand, our bills are now close to 30% of what they would be without the panels. Our bill for May , even though our usage has been been pretty constant, was $27.40. Here are the numbers so far:
The Technical Details
Our installation is a 3.6kW system designed and installed by Heritage Solar in Aliso Viejo. We are very pleased with their work, their attitude and their price. The system consists of 24 SolarWorld SW-175 panels tied to the grid via a Xantrex GT3.8 inverter.
Are We Glad We Did This?
No question. Clearly, this is a major investment. We paid about $21,700 upfront for our system; state and federal rebates paid the other $10,000 the system cost. I don’t think we lost any money, starting from day one: the value of our home has increased because of the solar installation by about the our out-of-pocket cost. But our goal was not just to reduce monthly bills, as important as that is. We also wanted to reduce our dependence on fossil fuels.
According to the EPA, if we generate an average of 15.5 kWH daily [and today are are at 19.8], we are preventing the equivalent of 1 pound of CO2 from going into the atmosphere every hour, 24 hours a day, 365 days a year, every year from now on. Now, as far as global warming is concerned, that’s cool.
June 11th, 2007 at 8:26 pm
This is beautiful! As you know, we are also a 2-hybrid family with solar panels. We have a much smaller installation than you - about 1/3 if I remember right. But we also have flourescent bulbs throughout the house and it was designed to be “green” meaning that the ac system, insulation, ect. was done with energy conservation in mind. We moved recently from a smaller house with none of this and our energy payments are a fraction of what they were. I need to get as scientific as you and actually do the measurements! I also agree that the primary benefit of this is reducing our carbon “footprint”. One could argue that this would be the right thing to do even if it cost slightly more! I have a friend in Canada who recently switched to a green energy provider (they can see the windmill on the island in their township!). It costs him twice as much, but he figured out a ways to reduce his consumption to half of what it was. Another good way to reduce carbon footprint if you can’t go solar!
August 16th, 2007 at 12:23 am
Nice writeup Alan. I took a look at Heritage; seems like an up-front company.
This is on our remodelling plans for the future.
December 25th, 2007 at 9:26 pm
Alan,
Nice sight - a big solar array on the roof.
The solar is really making a big dent in your air-con bill, and helping to pay back on your initial capital investment.
In energy terms however, it will probably take around 7 years before it’s paid back the kWh it too to manufacture it and transport it.
Here in the UK here, we don’t really need air-con, - just as well because we don’t get anything like the sun of Southern California.
Solar pV is of marginal benefit here, and the cost per peak watt is far more than you pay in the USA.
Instead, I have found ways of trimming my power bill down to just 2600kWh per year, and I have now invested in a vegetable oil fuelled combined heat and power system that heats the house in winter and generates all my power too.
I’m installing a woodstove/furnace for home heating to offset my natural gas consumption. I hope to make a big dent in my 13300 kWh per year natural gas consumption.
Working from home has reduced my annual mileage from about 12,000 to just 6000.
Happy Christmas and a prosperous New Year
Ken
London
December 26th, 2007 at 4:08 am
Ken:
Thanks for the comments. Clearly, a solar solution is not one-size-fits -all-everywhere; in SoCal it’s an easy call. And I haven’t seen numbers on embodied energy for solar panels; that would be interesting.
A good friend long ago pointed out that while my Insight gets very good mileage he gets even better numbers by working from home and walking or biking where he needs to go. True, true. Also not universally applicable, though.
Have a great year, stay in touch.
ak
December 26th, 2007 at 5:07 pm
Alan: As I write this, I am waiting for my Heritage rep to get here with contact in had for the installation of a 28 sanyo panel system. We hope to have enough room on the roof to be able to add more panels in the future, expecting that some sort of a plug-in hybrid car is in our future for the little trips around town. We just bought a low miles 2007 E-320 mercedes diesel. Drove it back from denver and recorded an honest 36.5 mpg. With ultra low sulfur diesel fuel, great new technology (turbo charger, 7 speed transmission, common-rail direct injection, a particulate trap etc.) I get at or near hyrid mileage with lots of passenger and trunk room. Our solar installation is designed to hit nearly 100% of our current usage, and I have a suspicion that we will encounter ‘usage creep’ as my wife tells me to stop following her around flipping off the lights.
April 6th, 2008 at 4:59 am
Excellent technical and customer service feedback. Heritage Solar should be turning your cost back as well! I’ve requested a quote as well. $21k is cheaper than a stupid car, and with all the other insane costs of living, we’ll likely stay here in Riverside awhile. I like the ROI especially and the fact that costs are quickly recaptured by home equity.
Personally I look forward to blasting the A/C during the 105 degree days. In the past we usally run about 90 degrees in the house because we cannot afford to run the A/C.
In addition, I signed up for the SCE ’shut off’ device for my A/C, which will save another $200 off my bill, but they rarely use that option (per a doctor who referred me to this program).