Dock lights

Indian River Joel · March 2012

Hi all, I am new to the forum. I have been google searching and checking out this forum for the last month or so. I have a few questions that I couldnt quiite answer by searching the forum. Please excuse my ignorance as my solar knowledge is very limited.

I would like to illuminate two flood light type lights on my dock. My requirements are this: they must be fairly bright and they must be switched. They will probably only be used an hour or two a night average.

Another thing, I would like to do is put a waterproof light underneath the dock facing the water. This light I would like to run all night.

Again, sorry for the noobie questions and any help you could provide would be appreciated. I am looking at something like this with a 12 volt marine battery. I am not sure if that will be sufficient enough?

http://www.amazon.com/Instapark%C2%AE-50W-Mono-crystalline-Solar-Panel/dp/B004OZDI7O/ref=sr_1_13?ie=UTF8&qid=1332961173&sr=8-13

http://www.amazon.com/gp/product/B001DZONCW/ref=cm_cr_asin_lnk

Joel

Edit: I am located on the central east coast of Florida, so I dont think sunlight should be too much of an issue?

BB. · March 2012

Re: Dock lights

Welcome to the forum Joel,

It all comes down to how much energy you want to do every night and how much sun you get during the day...

You could do this with 5-10 watts of LED, or a couple of 150 Watt flood lamps--Big difference in your energy usage.

Just to give you some guidence--Assume 3x 10 watt LED lamps, 2x 1 hour and 1x 10 hour per night. Assume 9 months of the year is ~4 hours of "noon time" equivalent sun and ~50% system efficiency (from solar panel to output power--For DC, it might closer to 62% system efficiency--but we can worry about the exact numbers later):

2x 10 watts * 1 hour per night = 20 Watt*Hours for above water floods
1x 10 watts * 10 hours per night = 100 WH for underwater flood
20WH + 100WH = 120 WH per night

Battery size--In general, for long battery life, assume using 25% of battery capacity per night (1-3 days of "no-sun" and 50% maximum discharge):

120 WH per night * 1/12 volt battery * 1/0.25 nightly discharge = 40 Amp*Hour @ 12 volt battery bank minimum

Now, we have two ways of calculating solar panel size... One is based on charging requirements for the battery and the other based on hours of sun per day--We try to meet both as a minimum panel requirement.

So, sizing based on battery size--We recommend 5% to 13% rate of charge. AGM batteries can certainly operate closer to 5% rate of charge--where as flooded cell I would suggest a higher value (flooded cell have higher self discharge and do not last as well at low states of charge):

40 AH * 14.5 volts charging * 1/0.77 panel+charger deratings * 0.05 rate of charge = 38 watt panel minimum
40 AH * 14.5 volts charging * 1/0.77 panel+charger deratings * 0.10 rate of charge = 76 watt panel nominal
40 AH * 14.5 volts charging * 1/0.77 panel+charger deratings * 0.13 rate of charge = 99 watt panel maximum cost effective

The next check is based on the hours of sun per day... Of course, this is based on your location, shading, weather conditions, and how many months of the year do you plan on using the system (9 months of the year except winter, 12 months of year, backup power supply available, etc.). Also if you are using a 120 VAC inverter or not. A basic set of conservative assumptions for 9 month system in math would look like:

120 WH per day * 1/0.52 system derating * 1/4 hours of sun per day = 58 watt solar panel minimum

So--based on a completely made up set of power requirements, the recommended panel size, based on my assumptions, would be around 58 to 99 watts.

Conservation (choosing energy efficient lamps, automatic shutoff timers) is critical to designing a system that will be cost effective and meet your needs. I would suggest a DC Current Clamp meter (cheap one here) or a DC Amp*Hour meter would be handy for you to evaluate your lighting loads. If you end up using 120 VAC lighting (might be a good idea if you mount power system on shore and have to run a long line to DC lamps at doc)--Then you can get a Kill-a-Watt meter or equivalent to measure your AC loads (also very nice for use around the home for conservation/appliance evaluation).

-Bill

Indian River Joel · March 2012

Re: Dock lights

BB. wrote: »

Welcome to the forum Joel,

It all comes down to how much energy you want to do every night and how much sun you get during the day...

You could do this with 5-10 watts of LED, or a couple of 150 Watt flood lamps--Big difference in your energy usage.

Just to give you some guidence--Assume 3x 10 watt LED lamps, 2x 1 hour and 1x 10 hour per night. Assume 9 months of the year is ~4 hours of "noon time" equivalent sun and ~50% system efficiency (from solar panel to output power--For DC, it might closer to 62% system efficiency--but we can worry about the exact numbers later):

Thanks for the quick response. In the scenario you presented, I am looking at around 140 Watts of usage per night. I guess I could go with a better panel or maybe I can rethink my usage of the lights? My usuage would probably be less than the numbers I presented you, but it is always better to be safe. I may make all the lights switched vs timed. I am just trying to plan this out

What kind of LED lights would you recommend?

2manytoyz · March 2012

Re: Dock lights

Hey Joel,

You're practically in my backyard! I'm on Merritt Island.

One of the solar charge controllers I'm using is a MorningStar Sunlight-10. Regulates up to 10 Amps (120 Watts). A slick feature about this controller is that it has the ability to control lighting via a built-in relay. When the sun sets, it starts a 10 minute timer to verify the array hasn't been briefly shielded from the sun. The internal relay then supplies up to 10 Amps of 12VDC to external lights. The amount of time they are on is adjustable by turning a small switch.

Attachment not found.

It can be set to any of these times:

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No worries of a timer, daylight savings time, longer Summer days, shorter Winter days... the controller turns on the light at dusk, and will run the lights for the number of hours you specify. I've used this charge controller to turn on the exterior lights at my last house for 4 years: http://www.2manytoyz.com/solarphase3.html

I've had great success with some LED spotlights I purchased from Amazon. Most LED lighting intended for garden lights are either very underpowered, or have a far shorter lifespan than the manufacturers claim. These are holding up well, and I've bought dozens of them for outdoor lighting.

These have an MR-11 type base (two pins). Typically found in outdoor 12VAC (not DC) lighting. These bulbs WILL operate from a 12VAC or 12VDC power source! Also not polarity sensitive. They have been operating for a couple of years, zero failures.

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These were $10 each when I bought the first batch. They are now $4.99:

http://www.amazon.com/gp/product/B002L4L606/ref=wms_ohs_product

Each fixture only uses 125mA, yet produces 140 lumen. I generally use two at different angles to illuminate trees around my house. They're cheap enough, and energy efficient enough, to use a handful if needed.

The fixtures I'm using are the basic $10 metal housings made by Malibu. I bought mine at a local Home Depot, but they are also available from Amazon:
http://www.amazon.com/Malibu-8301-9604-01-Watt-Flood-Bi-Pin/dp/B002ZRPMA4/ref=sr_1_sc_2?ie=UTF8&qid=1332983898&sr=8-2-spell

Good luck with your project!

Indian River Joel · March 2012

Re: Dock lights

Thanks Robert and Bill!

Robert, I live in Palm Shores so I literally am in your back yard!

This is going to be my first solar project and I am very excited about it. Robert, great idea on the controller and Bill thinks for helping me figure out the panel size. I am thinking that I really want to make the overhead lights switched because they will only be in use if I am out fishing or crabbing at night. Some nights I may be out there for 2 hours and probably most nights not at all. The light facing the water, I would like to run from dusk to dawn because it willl attract baitfish, crabs, and big fish in with it.

I plan on mounting the solar panel on the roof of the dock so the run shouldnt be too far. I am thinking about putting in a smaller system with 2 LEDs on the dock to get a better feel for what I am doing first. Those would be switched and would use an average of 1 hour a night. Do you think it would be a better idea to do a smaller system first to learn how solar works better?

BB. · March 2012

Re: Dock lights

It can be very difficult to "grow" a solar PV system over time. So--I would suggest that you research the lighting (get some samples, measure current/power used with a meter) you want to use and see how they work for you. Use a battery from your car/boat to temporarely power them and see if they have sufficient light for your needs (and LED's come in "different color temperatures"--I am nto sure which would work best for you--blue white or warm white, etc...).

I really do not have any suggestions on what lamps and where to get them.

-Bill

westbranch · March 2012

Re: Dock lights

FWIW the chain hardware stores around here are starting to carry Edison-27-base type LED bulbs in 110 format, so you might start there... 110 systems are cheaper but need an inverter

CDN_VT · March 2012

Re: Dock lights

I have purchased many of these from this person selling on E-bay. Item number: 390402388682
For the 12 volt usage I open the back and remove the 110v to 12 vdc driver pack and the just give the light straight 12 V.

I have had these working for just under a year in wet and freezing zone's.
18.99 each is a good buy for the light .

VT
YMMV

Dock lights

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