oops.... typos are soooo embarrasing: Corrected for clarity's sake:
In san Francisco, we get the equivalent of 7.3 peak sun hours in July, hitting a horizontally mounted panel. In January, we get the equivalent of 2.2 peak sun hours. For the whole year, we get an average of 4.7 peak sun hours per day . ________________________________ From: "Judith Blumhorst, DC" <[email protected]> To: [email protected] Sent: Wed, April 14, 2010 2:18:59 PM Subject: [IC27A] Re: Solar system [was: Inconvenient battery installation on Catalina 27] Hi Tim (And David) I have completed the first two courses for my solar designer certification with NABCEP, the North American Board of Certified Energy Practitioners. Let's see if I can help a little here.... Here's a real-world example, based on my homeport -- sunny San francisco, at latitude 38 degrees. A high-quality 135w solar panel will replace about 30 usable amphours per day to my high-quality batteries per day, if I have a high-efficiency solar charge controller. Where are you located? How much sun you get determines how much power your panels generate. The rating on the solar panel doesn't tell you what you're going to get in the real world. It's just an output rating in ideal conditions. (And the definitions aren't always what you'd expect). Good panels put out more juice than crummy ones when the sun isn't perfect. Efficient chargers constantly adjust the "maximum power point" varying varying the resistance to the panel so they put out the most usable amps at the right voltage. Good batteries have low internal resistance and can absorb a charge faster and with less wasted energy. With less than excellent components, you might get only half as much usable amp-hours out of your system. And your location makes a huge difference: To size a solar system for a given geographical location and climate, we use a concept called "peak sun hours" In san Francisco, we get the equivalent of 7.3 peak hours, hitting a horizontally mounted panel. In January, we get the equivalent of 2.2 peak hours. For the whole year, we get an average of 4.7 peak hours per day And then we have to "de-rate" the performance for factors like temperature, dust on the collector, electrical resistance, etc. An efficiency factor of .80-.85 would be excellent performance in the real world. .75 would be average. Here are some good links to play around with... For peak sun hour factors by city and state in the US: http://rredc. nrel.gov/ solar/old_ data/nsrdb/ redbook/sum2/ state.html For a solar system sizer (for off-the-grid systems) http://www.advancepower.net/advcalc.htm Fair winds, Judy B, ________________________________ From: Tim Millar <seascoutship76@ verizon.net> To: ic...@yahoogroups. com Sent: Tue, April 13, 2010 1:20:19 PM Subject: Re: [IC27A] Inconvenient battery installation on Catalina 27 David, Got my answer from Coleman/Stearns Consumer Service: The Coleman Solar Charging units are licensed products manufactured and distributed by ICP Solar Technologies, 7075 Place Robert Joncas, Suite 131, Saint Laurent, Quebec H4M 2Z2, Phone: 888-427-7652 or 514-270-5770 Ext. 133, info-customers@ icpsolar. com, http://www.icpsolar .com. That's one possibility - double battery, controller = about $140. Just searched eBay for "solar marine battery charger" and don't know what I'm looking at. I'd leave it hooked up in the cockpit on the mooring. We don't need much house power - just lights, radio, bilge and fresh water pump - plus the starter battery for Universal M-18. Suggestions? Tim Even if the Coleman ones are end-of-life' d, there are a TON of solar panels of all shapes, sizes, and wattage on eBay for cheap. I had picked up a one-watt panel for about $6 (shipped, no less) to trickle charge my car's battery during the week since I take public transit to work. One watt is not much juice but I wanted to squeeze more life out of my 5-year-old battery and that was a cheap way to go about it. Maybe next winter will be the death's door for it...David
