Judy, Thank you so much for all this valuable information. This will save us having to go through 6 books and 11 websites to find out this much information and it is all relative to what we want to accomplish. I've been wanting to put on a solar panel but was gun shy because I was ignorant on the subject. Thank You, Thank you !! Dick Schmidt
--- On Wed, 4/14/10, Judith Blumhorst, DC <[email protected]> wrote: From: Judith Blumhorst, DC <[email protected]> Subject: Re: [IC27A] Re: Solar system [was: Inconvenient battery installation on Catalina 27] To: [email protected] Date: Wednesday, April 14, 2010, 9:07 PM Rick, What is your goal? To keep your batteries trickle charged on a mooring? Or to go "off the grid"? For a trickle charge panel, less than 10 watts, you. 1. Trickle charging: For a trickle charger, the rule of thumb ishat your panel should provide about 1 watt or less for every 25 amphours of battery capacity. If your panel provides more than that, you'll damage your batteries. For a 90aH battery, a 5 watt panel is close enough and you won't hurt the battery. If you have AGM batteries, which have lower internal resistance and a negligible rate of self-discharge, you can use a 2 watt panel to keep your batteries topped up. For a two battery bank, a nice system would be a Unisolar flexible 11 watt panel and a dual battery controller. I like the Flexcharge PV7D. It's a smart-charger, very effieicent, will charge both batteries, and can handle up to 7 amps from the panels. It's under $100 at West Marine and can take a beating or a dunking. That's what I have for my trailer sailboat that doesn't have shorepower available. (And AGM batteries). In sunny San francisco, the 11 watt panel recharges the amps we use on a weekend daysail (for lights, radio and occassional autopilot use,) as well as maintains the battery. We don't have or need a cranking battery, just enough for one light inside and the vhf and the stereo. We rarely sail at night, and we carry battery powered backup lights for longer trips, just in case. 2. Small solar system for 3 season use "weekender" use, providing moderate creature comforts: The biggest panel manufactured for 12v systems is 135watts. For that you would need a conroller. A 135w panel is the largest one made for 12 systems, and they generally can't produce more than approx 7.5 amps per hour under ideal conditions, no matter what the voltage. So you could use a 7-10 amp controller with a single 135w panel. You can put together a nice135w system with controller for under $500. Depending on your weather, that'll give you up to 50 amphours a day in the summer, 30 in the fall/spring and 15 amphours in the winter. That's just right for a two bank system of about with two house batteries of 90-100 aH each. Use one battery for the engine and use the other two for the house. You'll have one days' reserve capacity in the house bank if it rains. In the winter, you're not going to get enough juice to use all your creature comforts, so use shorepower. 4. Off the grid livaboard system: For an "off the grid" 12v system, to provide more creature comforts, costs jump geometrically. You'd need a lot more panels, wired panels in parallel, and a controller with the apropriate amperage range. Now we're talking around $250-300 and up for a controller. $300 per panel. Mounting systems for the panels. Wiring costs increase as the diameter of wire increases. And if you really want to go off the grid, then you need to invest in a much larger battery bank. So now we're adding more weight and more expense. 5. The moral of the story: If you can keep your consumption down to 25-30 amphours per day of usage for spring/summer/ fall, you can get away with about $500 for the solar system, (and $500 for two nice AGM batteries that'll last you 7 or 8 years and charge up really fast) 6. Or get a Honda 2000i gas generator for $1000.... and run it on the foredeck. Use your fridge and microwave as much as you'd like.... ~~~~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~ I plan to buy a 135w panel. 135watts/12v = 11.25 amps right? So if I have my 135w panel out for an hour at noon, I should get 11 amphours worth of charge in my batteries, right? Sorry, but that's not how it works. You'll get about 6 amphours back in your battery bank in one hour at noontime. A 135 watt panel can't produce more than about 7.5 amps. Photovoltaic panels are nominally rated at 17.7 volts... so that they produce enough voltage to charge a battery even if conditions aren;t perfect and part of the panel is in shade .So 17.7v * 7.5a = 135 nominal watts. But at 12.3v the equation works like this: 12.3 * 7.5 = 92 watts. To figure the output of a system, you use the 7.5 amps x the number of peak sun hours. then de-rate that output by 0.80 (average) for system ineffieicencies. So you get 6 amps per hour in the noon-day sun. (You need between 13.5 -14.3 volts, which is the range that's required to fully charge a battery. And if the day is too hazy, or the sun angle too low, or more than about 30% of the panel is shaded, the voltage drops too low to charge the battery.) That's all I can tell you in general. Designing a system gets down into the particulars. But I hope this helps provide some practical guidelines for cost vs. benefit. Fair winds, Judy B From: Sonshingle <sonshin...@yahoo. com> To: ic...@yahoogroups. com Sent: Wed, April 14, 2010 4:21:03 PM Subject: Re: [IC27A] Re: Solar system [was: Inconvenient battery installation on Catalina 27] Judy, This is excellent information and thanks for sharing it. What have you learned about voltage regulation to the batteries? I understand there has to be some sort of regulator to prevent overcharging and that good regulators carry a pretty good price tag. Dick Schmidt Greenville, NC Rush NoMore --- On Wed, 4/14/10, Judith Blumhorst, DC <drju...@blumhorst. com> wrote: From: Judith Blumhorst, DC <drju...@blumhorst. com> Subject: [IC27A] Re: Solar system [was: Inconvenient battery installation on Catalina 27] To: ic...@yahoogroups. com Date: Wednesday, April 14, 2010, 5:18 PM 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.advancep ower.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
