Solar Panels

[Belchy]

Been looking at the solar panels in Canadian Tire, and wondering if they would work well for charging my battery while I fish all day. On my accessory battery, I run a fish finder and a 12V trolling motor, just wondering if the solar panals would work or not. Any suggestions would be greatly appreciated.<br /><br />Thanks again<br /><br />Belchy

 

[Paul Moir]

Re: Solar Panels

Belchy, when I looked into it a while ago, the answer was if you wanted to recharge a battery the solar panels were worthless. You'd have to literally cover the boat in panels to get an barely acceptable recovery rate.<br />They're great for maintaining a battery from self-discharge.<br />Say you got the 15W one from C T for $149. That supplies 1.2 amps maximum to the battery if the panel is in full light and tilted toward the sun. There's no way that's going to keep up with a trolling motor which is drawing down (bare minimum) 30 amps: you would need 30 hours of full sunlight to cover 1 hour of trolling motor use.<br /><br />Looks like there will be a product coming out soon which promises to drastically reduce the price of solar panels while perhaps improving performance. Keep your eyes open.

 

[Boatist]

Re: Solar Panels

I agree with Paul. It would not keep up with your fish finder. No way could charge enough for a trolling motor.

 

[ZmOz]

Re: Solar Panels

Yep...unless you have enough panels to sink your boat, it will barely keep up with the battery's selfe discharge rate.

 

[stevens]

Re: Solar Panels

I think you guys are being a bit too critical here.<br /><br />Looking at some small size (21"x27"x0.15) panels in stock at the local boat store, they are capable of delivering up to 35W and 2,13A. That's more than enough to keep a fishfinder, a radio or a large cooler going. My such units drain 700mA, 2A and 4A, respectively.<br /><br />You are of course right in that this wouldn't be nearly enough to keep up with the 10-50 Amp power drain of a trolling motor.<br /><br />However, this should be sufficient to recharge a battery over a few days during the week, waiting for the next weekend to arrive.... (but I'll be the first to admit that I haven't tried this myself)

 

[gewf631]

Re: Solar Panels

This topic seems to come-up every 6-months or so...<br /><br /> Here's one from November <br /><br />I picked-up an inexpensive one from Harbor Freight, for about $10, and use-it just as Stevens suggests. In fact, in the off-season, I swap-it around between my garden tractor, motorcycle, battery-pack, and generator, just to keep the batteries 'topped-off'. Seems to do the job just fine.<br /><br />Ed

 

[ZmOz]

Re: Solar Panels

Originally posted by Stevens:<br /><br />Looking at some small size (21"x27"x0.15) panels in stock at the local boat store, they are capable of delivering up to 35W and 2,13A. That's more than enough to keep a fishfinder, a radio or a large cooler going.

Key words here are "up to 35w". That is only under the most perfect conditions, which will never happen. Even if you do get good light, and manage to get 75% of the panel's output, that only lasts for an hour or two each day. Simply not enough for any electric device you might find on a boat...

 

[Dunaruna]

Re: Solar Panels

There are many different and varied configurations of solar panels. Some perform poorly, some are close to 100% efficient. The absolute bottom line is - the good ones cost big bucks.<br /><br />1 x 5amp (60w) monochystaline panel with a smart controller is ample to maintain a deepcycle, it won't 'keep up' with a troller discharge but it will maintain given that the average trolling time is way less than the average sunshine time.<br /><br />Aldo

 

[ZmOz]

Re: Solar Panels

Originally posted by Dunaruna:<br /> There are many different and varied configurations of solar panels. Some perform poorly, some are close to 100% efficient.

The absolute most efficient solar panel you can buy is around 15% efficient. There is no such thing as a 100% efficient solar panel.<br /><br />

Originally posted by Dunaruna:<br /><br />1 x 5amp (60w) monochystaline panel with a smart controller is ample to maintain a deepcycle, it won't 'keep up' with a troller discharge but it will maintain given that the average trolling time is way less than the average sunshine time.<br />

A 60 watt panel will put out about 3.5 amps in the best of best conditions that never happens in real life. You're more likely to get 2.5-3 amps out of it in really good sunlight - and even in the best conditions, you only get that for about 5 hours a day - IF you continually aim the panel towards the sun. Also, a 60 watt panel will be about 30x30, I don't know about you, but I certainly don't have room for that in my boat.<br /><br />Conclusion: If you want to spend about $500 for a panel that will take up most of your boat you can get about 13 amp hours per day under ideal conditions.<br /><br />If you need away from home charging, get a generator...

 

[Dunaruna]

Re: Solar Panels

I respectfully disagree. I run 2 x 90watt panels. At peak times they give me 14 amps per hr, that is very close to 100%. They deliver (on average) 110 amps per day - everyday of the year, free of maintenance, garanteed for 20 years.<br /><br />Solar panel designs and manufacturing techniques have advanced greatly in the past couple of years. A 60watt mono panel with 36 diodes will put out 5amps in full midday summer sun with the panel tilted accordingly. It will also still perform (albeit at a reduced rate) when up to 3/4 shaded. <br /><br />Aldo

 

[ZmOz]

Re: Solar Panels

Originally posted by Dunaruna:<br />At peak times they give me 14 amps per hr, that is very close to 100%.

That's not how you figure a solar panel's efficiency. The efficiency percentage of a solar panel is how much of the sunlight per square inch it actually converts to electricity.<br /><br />

Originally posted by Dunaruna:<br />A 60watt mono panel with 36 diodes will put out 5amps in full midday summer sun with the panel tilted accordingly.

The wattage of 12v solar panels is rated at 18v. That means a 60 watt panel, at most, can put out 3.33 amps. That is the definition of a 60 watt panel. Even if you managed to fit a panel capable of 5 amps in your boat, it would hardly keep up with your electronics...

 

[Moody Blue]

Re: Solar Panels

I have to side with ZmOz on this issue. Sorry Dunaruna, I don't know your exact situation but I am amazed, to say the least, that you are getting that kind of output. I performed some tests two years ago on a variety of commercially available panels intended for RV'ers and boaters. I measured output voltage and current sourcing abilities at different loads under direct sunlight, midday, and was not able to get anywhere near the advertised outputs of these arrays. I think that mfr's must put the theorectical performance specs on the packaging when they sell them. I still see solar panels as trickle chargers at best, certainly not capable of sourcing large amounts of current to drive any substaintial loads.

 

[KRS]

Re: Solar Panels

I have family that lives "off the grid" utilizing solar panels and a generator charging a bank of batteries on their home on the beach far far away...<br /><br />100% effeciency is unheard of. They have used panels for 20 years on their home. They get 15% effeciency from them, and they replace them when they fade, keep them clean, track the sun, do a solar power dance and offer sacrifices.

 

[18rabbit]

Re: Solar Panels

A lot of people don’t realize you need to disconnect solar panels at night. If you don’t, they work in reverse, sucking electricity out of your battery and projecting it as a barely visible, low-level light into the night sky. I think that’s why the moon glows brighter on some nights, more people that forgot to disconnect their solar panels.<br />

 

[Dunaruna]

Re: Solar Panels

I'm the first to admit when I stuffed up but I'd like to point out that I never said 100 efficient, I said 'close to'. According to my FLAWED figuring, I am 'close to'.<br /><br />As for sucking power off the batts at night, that's what this is for......... web page <br />The unit to the far right controls everything and it gives me very accurate amp/volt readings, both average and instant. it also stores (archives) data, that's how I know exactly what's been happenning while I'm away. <br /><br />I still believe that solar is a viable option, space permitting.<br /><br />Aldo

 

[cuzner]

Re: Solar Panels

Just to jump in with a comment, most newer solar panels have a diode instaled to prevent energy loss with no sunlight.I have 2 of these, one bought at Canadian tire, one from a V.W..And I do use them when I,m away from the dock.No I don't depend on them to run a fridge or microwave,but to HELP replace some of the juice I loose from electronics, or lights. Just becuase they won't replace a 10 amp charger does not mean they are useless....just my opinion.<br /><br /> Jim

 

[Realgun]

Re: Solar Panels

Here in New Mexico we can get 110% of rating on a solar panel for 4 hours a day. We got intense sun here!!! and a mile or so lees atmosphere too.

 

[Moody Blue]

Re: Solar Panels

WOW, 110% of rating, and a mile less atmosphere ? What SPF sunscreen do you use ? 500 ?? Can you shine a little of that surplus sun my way ? Its been a cool and wet weekend here.