Solar Panels

Bill Roosa · Jan 10, 2012

Try solarwindusa.com. They have basic kits to build your own at great cost savings. 250 watts for $200!!!
Note that the kit may require some engineering to get the most watts out of it. "As built" it would put out 31 volts at 8 amps which is over the max voltage my regulator can handle. I split it into two panels which drops the panel voltage to 15.6 and give a combined output of 16 amps. YMMV
The whole "how much area should I purchase" really depends on the daily load and your local weather/location. Cloudy Washington would require more area than sunny Lake Mead for an identical load scheme.
The best place to mount the panels is where they can get the most sun (duh!). If you can angle them toward the sun you can get a significant increase in output (or reduce the amount of area you need). Google solarstalk for ideas. I'm thinking 6" PVC pipe and some crafty mounting/engineering would work as well as aluminum.
You would only need a regulator if the panel max amps are greater than 10% of the bank AH capacity. A 100 AH bank needs a regulator for panels that put out more than 10 amps.
The state of the art is an MPP (max power point) regulator. Next in line is the PWM (pulse width modulated) regulator and least preferred but cheapest is the shunt regulator. I would note that the MPP can take the 30+ volt output of the solarwindusa panel and boost-buck convert it to whatever is needed. So when the panels are only putting out 5 volts in the morning it boosts it to battery voltage and bucks it during mid day down to battery voltage. YMMV depending on the exact model you buy.
If you are considering adding more panels later or installing a wind generator you should consider buying a regulator that can handle the total load instead of buying a bigger one later. Also, wind and solar regulators are not interchangeable (they are really but it is not normally practical). Wind needs some sort of load dump and a load to dump excess output into. Think RV 12 volt DC electric water heater etc. Seems you can’t just leave a wind generator without some sort of load and you have to consider the windy day and the batts are charged situation.

Velero49 · Jan 10, 2012

Bill,

Do you have picture so your installation?

Bill Roosa · Jan 10, 2012

Tgrass
Your Mileage May Very

Velero
No I don't have any pictures.

Maine Sail · Jan 10, 2012

tgrass462 said:
Well hope everyone had a great Christmas and a safe New Year's celebration. I'm planning on what will be needed for next spring.

1. I must build a rack / shelf to hold the Kindles we (Tracy and I) received this Christmas

2. Tracy is working on a new jib bag on her Sail Rite sewing machine

3. I am starting to research solar panels / regulators to keep the two batteries in my Hunter 260 fully topped off during cruises between marinas. I've read some articles on the West Marine web site - now I'd like to pick the brains here on this forum ...

If any of you have experience in installing solor panels -

a. Did you purchase crystal or thin film panels?
b. How much area did you purchase?
c. Where did you mount the panels?
d. Did you install a regulator to keep from overcharging the batteries? If so can you provide details?

4. One item I can take OFF my list is my Garmin 541 S transducer. Last summer sailing in Lake Huron - my depthfinder on the chart plotter ceased working. Thankfully I had my trusty Eagle depth finder as a reserve (chart plotter worked great - just the sonar function went on the blink). Over Christmas I talked to the Garmin folks; they sent me an RMA # to return my 10 month old transducer AND the power cable to the 541 unit for new replacement. I tested the new cable & transducer in my kitchen - the transducer registered on the chart plotter AND it made a clicking sound. I'm crossing my fingers that my depth finder will work properly. Thanks Garmin for excellent customer support!

Tom Grass
Creve Coeur, Missouri

Tom,

Check out this thread it may answer many of your questions:

Installing A Solar Solar Panel (LINK)

Maine Sail · Jan 10, 2012

Bill Roosa said:
You would only need a regulator if the panel max amps are greater than 10% of the bank AH capacity. A 100 AH bank needs a regulator for panels that put out more than 10 amps.

Bill,

A 10A output panel on a 100Ah battery, without a controller, will cause damage to your bank. I suspect you meant watts not amps..? A 10A panel is in the neighborhood of 200 watts. I have seen a 40W un-regulated panel cook a 250Ah bank in about 7 weeks....

General consensus is that 3-4 WATTS for every 100 Ah's, though some suggest 10 WATTS per 100 amp hours is safe. I am leery of 10W per 100 though as I have seen a 15W panel holding a bank at 15.4 volts and the bank was two group 27's, but I forget which brand or how many Ah's.. But still this is below the 10% in watts to battery Ah and the full bank was sitting there at 15.4v in good sun. Of course at the point where you don't need a controller you've only got a "maintainer" panel that will really only keep up with self discharge. A small panel won't do much of anything to actually replace lost Ah's... A 4 watt panel will put out about 0.22A which is a long way from 10A.

sesmith · Jan 10, 2012

A couple of years ago, I bought a 15 watt panel and charge controller for our 23.5 from Silicon Solar similar to this one:

http://www.siliconsolar.com/12v-marine-solar-battery-charger-15w-p-130.html

It's all we use for charging our single battery. If you need something more substantial, give Rob at Southbound Solar a call:

http://southboundsolar.com/

I recently bought a solar lantern from him. He's a stand up guy and sells nice quality products.

Also, consider swapping bulbs out in your boat to LED's, especially the cabin lights and mast lights, as this will decrease your electrical load considerably, making solar charging even a better solution. We don't have an electric slip, and can spend a week at a time out on our boat without worrying about finding an electrical hook up to recharge the battery. The LED mast and interior lights on our boat don't use any more that the 15 watt panel can put back in during the day, but we don't have much in the way in electronics aboard.