Normally I don't like to talk about stories from other blogs, but this one really caught my attention. Slashdot put out a story on Lloyd Case. A geek in Northern California who installed a 6kW PV solar system on his house six months ago and is now a little disappointed with the performance. His most recent power bill was still $200 despite having a $60,000 PV setup tied to the grid.
A few tips to folks who are considering a PV system.
1. Roof Mounted Panels Suck - They often have limited or no tilt control and are clumsy to maintain. This means that you will likely get strong performance in summer or winter, but not both. Finding the average latitude tilt for your region and mounting the panels at that angle is your best option for roof mount. Trackers can bring your performance up by 1/3rd, but will include extra expense and complexity. Consider a manual tracking system which you just push with your hands through out the day if you need a early morning or late afternoon boost. This is ideal for the off-grid / unemployed eco-geek.
2. Grid Tie has issues too - Although grid-tie allows a PV install to greatly reduce their installation time and costs they also have some drawbacks. Continuing to buy power from a power company can result in relatively high monthly fees if the system purchased was undersized. Many grid-tie installations have no battery backup so when the grid dies, you lose all your juice too. In remote towns many power companies only pay the customer a 1/4 of what they charge the customer for power. My town being unusually behind the times refuses to purchase any power from their customers.
3. PV Batteries - New batteries are easy, but old ones can be fixed. Our world is hemoraging so called "dead - deep cycle batteries" aka "cores". Try talking to your local golf course, marina, or auto parts store. As you learn to test cells and repair lead acid batteries through desulfation you can save yourself a fortune in batteries and store large amounts of energy. Keep in mind that batteries are much like people. They like 72F temperatures and a little exercise. Do not cycle the batteries below 50% on a regular basis. I try to stay over 70% capacity on my battery array at all times.
4. Heat - My panels tend to have a pretty big drop off in performance during the summer. This is partly due to my not adjusting the PV array to be almost flat during June. It is also related to our monsoon season bringing in lots of rain and cloudy weather. However, the real killer of performance is the temperature. High temperatures drop my panel performance by 30%. Our temps in June peak around 100F which is enough to dramatically reduce the performance on polycrystal PV cells. The monocrystal cells are supposed to handle the higher temperatures better.
4 comments:
Hey, Mikey, did you consider a drip evaporative cooling system running over the panels to cool them? In the bad old days prior to freon air compressors, evaporative cooling was the way to go. Some of those agricultural drip hoses on the top of the PV with a slight angle.....
"Low-Tech"
Ganesh
Sounds like the fellow didn't adjust his lifestyle before going whole hog on solar. What a waste!
when I was involved with hydro power 25 years ago the policy of the federal energy regulatory commision was that utilities had to purchase surplus power. I do not think that has changed. you might have to fight them to get them to comply.
It is still the case that power *companies* must purchase energy produced by a consumer. However, there are many exceptions.
1. City owned utilities - this are exempt and there is no regulations that they buy power their customers produce.
2. Coops - These laws might be changing around this, but as far as I know there are no mandates in place that require Coop based power companies to buy back customer power. Many coops (including ones in my area) have already been buying back power.
3. Fair Price - some power companies in New Mexico such as Kit Carson had only been offering $0.04 a kwh to their solar producing customers. This is what power company buys coal based energy for. I believe several angry customers have been working a deal with kit carson to get them up to the current $0.13 a kwh rate.
I'd love to see a across the board mandate that says anyone who who sells power must buy back from their customers. If the customers power is clean then the power company must pay additional fees to the customer.
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