Friday, March 5, 2010
Buy more panels and call me in the morning
After several suggestions and theories--from two installers, an electrician, Stew, various blog readers, friends, and equipment manufacturers, among others--it turns out that Stew's German orthopedic surgeon-cum-solar energy wizard was right all along.
We don't have enough panels in our array to keep us going through the shorter days of winter. Doktor Schmidt says his house has 18 panels, so many in fact that he ends up selling electricity back to the government-owned utility most of the year.
That's six panels more than we have. Panels go for about $1,000 US apiece though there are reports the price has gone down sharply in the past few months. Still, this is not an inexpensive pasttime; we've already spent approximately $27,000 US. Payback on that would take, hmm, about 20 years, using the current electric rates, probably a little less, if you factor in the constantly escalating electric rates in Mexico.
It's probably easier too for Schmidt to finance his solar panels emporium: His practice revolves largely around American and Canadian geezers who keep tripping on San Miguel's cobblestone sidewalks and streets, or otherwise clamoring for various types of osteo-muscular tune-ups. Life past 60 becomes like keeping a '67 Chevy running, I tell you. It's amazing how many bones, tendons, discs, muscles and what-have-you there are in the body and how many things can go wrong. And Schmidt will fix them all and give some solar advice as a bonus.
The Schmidt Solar Hypothesis is that solar installers after a few years start working with a same-old, same-old formula of 12 panels for a "normal" household, without considering individual use patterns. A family with one-year-old quadruplets with happy bowels probably will have to run the clothes washer and dryer eight hours a day.
Stew and I don't have that situation, but we still use the dishwasher daily and that sucks about 1.4 kw a cycle, or almost the output of a couple of panels on an average day. Other folks here just hire a maid to wash the dishes, which given local labor rates, is a better deal financially than running a dishwasher--assuming you don't mind having the maid in your house every day of the week. Stew and I do mind.
Schmidt says that low-balling the number of panels also serves the purpose of preparing an estimate that won't scare off the potential customers who might swallow a $27,000 estimate but gag at anything over $30,000.
In an effort to pin down the problem with our solar system, our installer hired an electrician/building inspector who showed up with a gadget called The Energy Detective, or T.E.D. (Photo above, check out the following website for more information: http://www.theenergydetective.com/index.html)
The T.E.D. is wired to the entrance electric panel and monitors and records the amount of juice going through 24 hours a day, and sends a readout to the gadget above, which is about the size of an electric alarm clock. At the end of several days the information can be downloaded into a laptop computer, which will print out a report as precise as minute-by-minute electric use.
Some of the readings are surprising, particularly regarding electricity users that can't be monitored with our own gadget, the Kill-A-Watt. This gizmo, about $15, is mostly for appliances that can be plugged into it.
(Check it out: http://www.p3international.com/products/special/P4400/P4400-CE.html)
The T.E.D., for example, showed that five, six-foot-long, recessed "rope lights" in the living room use 350 watts, a good bit considering they hardly give off any light. The desktop computer I'm writing on--and its little electronic friends, such as separate speakers, two printers, routers, large screen, etc. etc. can use about 250 watts when they are all whirring along. The famously efficient (as far as propane, that is) Rinnai space heater has a 130 watt blower. You run that baby for eight to ten hours a day during the winter, when solar production is at its lowest, and you'd better have a 1.5 photovoltaic panels for that operation alone.
The T.E.D. readings showed that on a normal day we use between 7kw and 8kw, a relatively low consumption rate particularly if the panels--as they have during the past brilliantly sunny three or weeks--generate 12kw of electricity in a day. So far today, at 4 in the afternoon, they have already generated 11.3 kw. That's fat city, isn't it?
Not quite. Part of the juice goes to run the appliances, but you also need additional electricity to keep the batteries charged for when the sun goes down, or The Lady Upstairs decides that two or three weeks of cloudy days is good for building character.
Earlier this year, around the end of January, beginning of February we had two or three weeks of almost unrelentingly cloudy and cold weather. Our Rinnai heaters tried to buzz along but the batteries didn't have enough electricity to keep a charge, let alone run the house.
The systems of many Solaristas in San Miguel, including the guy who installed our batteries, simply crashed. "It's never happened before!" "We've never seen anything like this!" Yeah, and yadda, yadda, yadda.
Our solar problems are not entirely solved yet, though weeks and weeks of sun certainly make life easier. We bought a cheap voltmeter that tells the batteries are at 25 volts (fully charged) or slightly above practically all the time.
For anyone interested out there in blogger land, I'd like to offer the following nuggets of advice.
1. Find a reputable and experienced installer. An engineer at Outback, the firm that makes part of our hardware told Stew that the solar energy field has become a sort of gold rush, often populated by people who don't know what the hell they are doing or believe installing solar systems is as easy as selling salted pretzels on a streetcorner. Our installer is probably the best in town but still we wish we had known more about what was involved. The Outback engineer said that fast-talking is not a phenomenon just in Mexico but in the U.S. too. Now, that makes me feel better.
2. Figure out how much sun your area gets. You need more panels in Bismarck, N.D., than in Phoenix, and there has to be a formula or database that would tell you how much sun your panels are likely to receive, particularly in the winter or rainy months, and from there, how much electricity you are likely to get. "We've never had this problem before!" or "I've installed dozens of these without a problem" are not an adequate equivalent for figuring how many kilowatts you're likely to get, say, in January or how to proceed and plan for what else you need.
3. Make a realistic, thorough inventory of how much electricity you need to satisfy the needs of your lifestyle. The sustainable or off-grid housing field has way too many evangelists and seers who'll try to lecture you about the wonders of charging the batteries with a biomass generator under the kitchen sink, or worse still, start ranting about the intrinsic evil having a big, fat, flat-screen TV in your living room, or the gluttonous "American Way of Life."
Stew and I don't watch TV that much but if you do, go for the big TV. Just make sure you design a system that is adequate for your needs. On the other hand we do like our dishwasher and wish we had planned a little more carefully.
This is a modern technical question not a medieval morality play. Don't commit to living in the dark or having an eight cubic foot refrigerator unless that's what you really want. If so, you might get away with eight or ten panels.
4. If you're building from scratch, spot an architect and electrician familiar with energy conservation. Our Mexican electrician did an excellent job thanks to both, his under-the-radar apprenticeship in Atlanta and Stew's experience as a home inspector. The architect came up with some great ideas--and forgot a few basic points. He put large windows and skylights in every room of the house--even the master closet--so there's no need to turn on lights until the sun goes down. However, he is very fond of 50w halogen lights which are energy hogs (try LEDs), and originally wanted to put a ring of 24 or 25 lights all around the base of the house to, I dunno, emulate the spacecraft in "Close Encounters"?
Those rope lights are coming down. Whose idea was that? If you turn on the rope lights in the living room and around the skylight by the kitchen, you'll have a good 500 watts of electricity going through and not much light to show for it.
5. Get an automatic generator, run by propane or natural gas, to kick in when the sun fails--as it will inevitably. During last January's penumbra, Stew and would have to fill the generator with gasoline, keep an eye on it, and so on. That's a pain that could have been avoided with an automatic unit.
For the time being, we are fine with our system. But in June the rains start and presumably less sun, so maybe the three additional panels can't wait until the winter.
Any suggestions or ideas, feel free to post comments or e-mail me. Thanks.