Solar Aquarium Lighting?

fust · March 2012

Hey there, total solar n00b here trying to see if I can run part or all of my aquarium on solar. I found one old thread on the subject, but couldn’t glean what I needed. Maybe I’m using the search wrong, since I couldn’t find anything on running 20W LEDs at all, which seems weird. Even though I am relatively geeky where soldering iron's are concerned, I don't have time to become a solar engineer just to do this one project, so I thought I would ask over here. Any help anyone could give me would be greatly appreciated!

I think the simplest way to lay this out is to give my needs/desires/limitations/etc., and just let the comments come (since I really don't know what I'm doing solar-wise). Here goes.

I have a reef aquarium. At this point I am using 6x40W florescent tubes (4ft T8 ), but I am interested in using LEDs instead, since what I have is not actually even enough light, but uses more power than LEDs. I am going to upgrade, and thought this would be a good time to consider solar. Ultimately, I from what I have read about reef tanks, I would want to run about 100W worth of LED lights. I was thinking 5, 20W ~5v LEDs, each with its own 12v to ~5v driver. I would like them to be on for 8 hours/ day, so that's 800Wh. I could power just part of them, and the rest from grid power, if need be, since I am making the lights.

I would like the solar element of this project to be modular as I go along, as money becomes available for the project. I currently own a 20W solar panel, and want to build on this. I'm thinking I could get a charge controller that is up to the task of the while lighting system, a battery or two that would get me off the ground (but could be expanded), and two more 20W panels to start. Again, if it just offset some of the power use at first that would be fine. But later I would like to expand and try and do the whole thing off grid (or most of it).

Where I live, I can get an average of 5 hours per day (per a map of the US with averages that I found), maybe a bit more in my specific location. I have tried a few solar calculators to figure all this out, but most seem to deal with power bills, not power needs, and/or are trying to sell you specific systems. Plus, my needs are not static, since they could change depending on the outcome of this question.

I don't think want a grid-tie system, because I want this to be somewhat portable and would also like to have a backup power source for emergencies if I need it. If the power goes out I could disconnect the lights and throw my inverter on the system and plug in the heater and a circ pump so things stay stable in the tank.

Also, is there a way to automatically supplement charging of the batteries with grid power if the panels are not delivering enough?

I know I’m shooting in the dark here, but am I completely nuts? I am open to all suggestions on this. Thanks in advance!

fust · March 2012

Re: Solar Aquarium Lighting?

You know, maybe a better approach to this is:

how many watts can I run for 8 hours per day with:

-my 20W cell,
-a cheap 7A inverter like this: Kintrex SPC0601 7 Amp 100 Watt 12 Volt Solar Power Charge Controller, and
-a single 12v 35Ah deep cycle battery in the $100 range (Interstate DCM0035),

without destroying the battery or anything else?

westbranch · March 2012

Re: Solar Aquarium Lighting?

welcome. first lets look at lights (load), you need to decide how many Lumens you need , determine the number of bulbs and then determine the load you want to supply to the battery, then pick the battery and then the solar panel and charge controller to match what you are trying to do..
hth

BB. · March 2012

Re: Solar Aquarium Lighting?

Not to be flip, but almost nothing useful...

I guess you are somewhere in the San Francisco Bay area--But depending on where (on the coast or the east bay)--the amount of sun can be a big difference (I am in San Mateo CA).

Backing up a bit... The first question is are you trying to save money, "go green", and/or have a backup power system (storms, earthquake, etc.).

The first thing we always push is conservation. It is almost always better to spend money on conservation first before you pay for Solar/Renewable Energy power.

For your system, lights, pumping, possibly heating/cooling are all big consumers of power. Just for a guess, lets estimate your power usage as:

Lights: 140 watts * 10 hours per day = 1,400 WH per day
Pumping: 20 watts * 24 hours per day = 480 WH per day
======================================
1,680 WH per day (1.68 kWH per day on your PG&E Bill)

There are three major types of solar power systems:

1) Grid Tied--The cheapest/most reliable/least maintenance (solar panel+Inverter connected to utility power--No backup power)
2) Off Grid--The most expensive. Solar+charge controller+batteries+Inverter for off grid/backup power
3) Hybrid--Grid Tied when utility is running, Off Grid when power fails. Cost ~between 1 and 2

So, assuming 4 hours of sun per day for 9 months of the year. 0.77 System Efficiency for Grid Power; and 0.52 system efficiency for off grid power:

1,680 WH per day * 1/0.77 GT system eff * 1/4 hours of sun per day = 454 Watt minimum GT array
1,680 WH per day * 1/0.52 Off Grid Eff * 1/4 hours of sun per day = 808 Watt minimum Off Grid solar array

Basically, for a pure off grid system, the average cost per kWH is on the order of $1-$2+ per kWH -- Or about 10x the cost of utility power.

GT systems in California can make economic sense--But it depends on how much power you use (tiered power pricing).

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

Thanks for the replies and the welcome!

The thing is, lumens are not so much the issue with reef aquariums, it's PAR (usable photosynthetic light-can't remember what the PAR acronym stands for), so all I really have to work with is the LED wattage ratings. I will be using a combination of blue and white LEDs to get the proper spectrum of light that penetrates deeper water, and the lumens are all out of whack with that setup compared to the "normal" lumens ratings used in lighting for humans.

The load I would like to work with is 100W @ 12v, for 8 hours per day. That said, the bits and pieces I have been able to pick up from here and there seem like they are saying that I will need something way beyond my current budget to achieve that much power without damaging the system.

Hence my second post about what I can reasonably run using what I already have as a starting point.

BB. · March 2012

Re: Solar Aquarium Lighting?

I should also add that if you are looking for backup power--A small Honda eu2000i (~$1,000) or eu1000i (~$800) (1,600 watt/900 watt max) genset may be a better solution. Depending on your exact power needs, you can run upwards of 24 hours per day on 2 gallons of gasoline... 10 days of backup power on 20 gallons of stored fuel.

I would love to have an off-grid backup system--But the last multi day power outage that I had here was on the cost around 1960 when a huge storm took out many of the power lines on the coast (yea-I was 4 years old).

Otherwise, the 2 hour outages every couple of years--I can live without backup solar power (have a genset of one type or another for many decades, and it really has never been worth firing one up).

I still have a Honda eu2000i and 20 gallons of backup fuel (my best performing asset--seems to gain $1 per gallon per year

). Use it for genset, emergency for car, camp stove, etc... And recycle it once a year into the vehicles.

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

Biil:

I thought your first line was what I would get

, but what actual calculation could I use to find out how many watts of LED I could run on that little system.

And what if I changed it up and threw together a 100W array? Does the picture get any brighter?

As far as purpose, I see "going green" (I hate that phrase now...) and saving money (over the long haul) as the same thing. I want to do that, AND if there were a side benefit of backup power, it would be worth it to spend for that.

And what about the AC charge backup for when the panels are not producing enough?

fust · March 2012

Re: Solar Aquarium Lighting?

And I think a few hours of backup would be fine.

I live in the North Bay, where we get higher-than-average sun days compared to the rest of Sonoma County, but not by much (but significantly more than San Francisco).

BB. · March 2012

Re: Solar Aquarium Lighting?

Fust,

I have to go now--But I too agree that "going green" and conservation/saving money are are pretty much the same thing...

A 20 watt panel will supply around 40 Watt*Hours per day (February or so) for AC (or DC) power use...

You can go with Grid Tied systems in chunks of 200 watt solar arrays at a time--However, you have to pay for building permits, contractors, electricians, etc... Realistically, you are looking at 3kW of solar arrays to make it worth while (and I think that the big solar leasing guys are aiming at 6-10kW systems in their radio ads around here).

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

Excellent info, thank you!

But to be honest, I'm not sure how this works, since I'm just exploring this option. Can I take this:

"A 20 watt panel will supply around 40 Watt*Hours per day (February or so) for AC (or DC) power use..."

to mean that since my 20W panel will produce 40 Watt Hours per day, if I were to have just fewer than 40 Watt Hours of drain on the system (excluding efficiency loss), then the panels could just keep up with the charging task? If so, then I could effectively only run <5W of LED lighting for 8 hours per day?

BB. · March 2012

Re: Solar Aquarium Lighting?

Yep, you got it... In reality, some days produce more energy, some less... The "4 hours of sun" is a 20 year average (roughly)... For example, PV Watts is a simple program to use. The nearest station to us is probably SFO airport (fixed array, tilted to around 38 degrees up from horizontal):

Month    Solar Radiation
(kWh/m 2/day)
1      3.62     
2      4.59     
3      5.22     
4      6.11     
5      6.36     
6      6.47     
7      7.01     
8      6.67     
9      6.62     
10      5.41     
11      3.87     
12      3.35     
Year      5.45

So, you can plug in the average hours of day for each month to figure out the "nominal" available power (you should probably plan on using about 75% of nominal maximum per day--on average unless you have backup power available).

If you are in Montara/Half Moon Bay--You probably will get much less sun in the spring/summer (coastal marine layer). If you live in Hayward or farther east--You probably will do better than the above numbers.

The 0.52 losses are for a "typical" off grid system. The 0.77 are typical for a Grid Tied system (no battery/conversion losses).

For an off grid system, it may cost you around $10-$20 per watt of solar panel to build a system.

For a grid tied system, around $5-$8 per Watt of installed panel (assuming 3kW or larger system).

Note, I am trying to be both conservative and "simple" in my assumptions when discussing your system. There are a lot of complexity in system design that would wrap us around the axle very quickly (different battery types, DC vs AC power, PWM vs MPPT charge controllers, your needs for emergency backup power, PG&E's rate plans, commercial vs residential, etc..).

More than willing to talk with you about the details--But the above numbers should be "close enough" for you to do some back of the envelope calculations to see what would work best for you (and your wallet).

I would highly suggest getting a Kill-a-Watt meter (or similar) and measuring the power usage of your aquarium components (and even your fridge, computer, network, printer, entertainment system, etc.) and see where your power budget is going.

Solar/backup power is expensive--both to build and maintain--so having an accurate power budget allows you to build what you need vs what you guess.

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

OK, great, thank you so much for all the info. Even if it's not what I want to hear. I just wish I could remember where I put my magic wand, life was so simple when I still had it...;)

westbranch · March 2012

Re: Solar Aquarium Lighting?

Hi again, to get back to the LEDs you probably need to investigate the degrees Kalvin that each 'bulb' operates at, as they are all different... the better dealers will be able to give you all the info needed to determine the suitability of their 'bulb'. you will note the variance in Lumens wrt frequency.

hth

BB. · March 2012

Re: Solar Aquarium Lighting?

Fust,

Not trying to stop you from trying solar-- but suggesting information/points of research before you spend your first $$$.

The Kill-a-Watt is of great use just for working on conservation--It is not unusual for somebody who has not "done conservation" before to cut their bill by almost 1/2 doing "simple stuff" (new fridge, unplugging the old under cabinet dorm fridge in the garage, laptop computer set to "sleep" when not needed instead of big desktop running 24x7, turning off loads that run in standby like digital sat/terrestrial receivers/TVs/Stereos/DVR's when not needed, etc.).

The standard home runs around 1,000 kWH per month and you can get down to 500-300 kWH a month pretty easily (assuming natural gas appliances/heating/no AC). For example, 500 kWH per month sounds pretty large--but when you look at a 24x7 average load:

500,000 WH per month * 1/30 days per month * 1/24 hours per day * = 694 Watt Load

Start looking at where the 694 watt load is going 24x7... Is it a fridge (should be 50 watt average, may be 100-200 watt average if old/problems), a desktop computer + monitor + network + printer can use upwards of 200-300 watts, etc...

Also, look at solar thermal heating... If you need warm water (say for your reef), solar thermal panels (copper/plate/glass/insulation/box) can be a fun DIY type project.

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

Hey, westbranch, thanks for the notes.

Kelvin is not so important as is wavelength in nanometers. Specific wavelengths are required for marine life such as corals and anemones, because they have a symbiotic relationship with a type of blue-green algae that lives within their structure. If those can't photosynthesize efficiently, the anemone dies. Kelvin ratings can be helpful, but since different mixtures of different parts of the light spectrum can produce the same Kelvin rating, you have to know which specific wavelengths the light source produces. Otherwise, you may have a nice looking 6500K light that does not have, for example, enough production of wavelengths in the 400 to 520 nm range (blues/violets) where the bulk of photosynthetic activity occurs, so your corals and anemones will suffer. Also, some wavelengths are used more by Macro Algae (the big nuisance stuff that fills your tank), and micro-algae (the stuff in the coral and anemones). People like a combination of "royal blue" and cool white or neutral white LEDs for their reef tanks because they have a good wavelength mix, although people also often over-blue their tanks, because it makes corals and whatnot "pop" due to the near UV produced. Looks great to us, but it's not natural. Cool White LEDs tend to wash out the tank color, too, so people try and over-compensate with blue. That's why the neutral white are better. They have some red in there to keep things a little less frosty looking (even though that can promote macro algae growth).

fust · March 2012

Re: Solar Aquarium Lighting?

Bill, I am actually already pretty well there on reduction, but I wanted to try and streamline this particular lighting project for solar, since that is the single largest power draw for a reef tank. I have a kill-a-watt (but danged if I cant find it), but it wouldn't help here because I am building a 12v LED system from components, not just buying an AC light, and the LEDs are the only thing I really wanted to run on solar. Right now, I don't even have sufficient lighting, and I am already running 1.92 Kwh per day with florescents. I have three, 2-bulb 48 inch t8 shop light fixtures with 40W aquarium-specific bulbs in them that run $20 a piece to buy, and need to be changed out every 6 months if you do it right. I slack off, and leave them for longer, but I get algae growth. If I switched to the 100W LED system, it should be a one time purchase, some soldering, and I'm in business for less than half the power draw and no more buying expensive bulbs all the time. I'm going to do this part for sure, I was just hoping I could do it more solar powered than it looks like I can (with my budget). Oh well, maybe I'll run a direct 12v water pump from the panel that is only on when there is sun out, which would probably be a nice way to keep the tank dynamic at least.

Eric L · March 2012

Re: Solar Aquarium Lighting?

furst,

I had a big reef tank in the '90s. As you know, they are very power hungry and running traditional one off a solar PV system is pretty much a no-go. But I did find some other efficiencies (this may all be 'old school' now):

- the Dolphin Ampmaster pumps were a huge improvement when they came out: 3000 gph for just 1.1 amp (I can still remember this figure). But they didn't like head pressure. I plumbed my tank with large-diameter pvc, and built a big manifold for the Ampmaster to direct the flow to various needs. I also raised the pump to the base of the tank, so there was almost no head pressure. It ran almost everything.
- I used a deep sand bed refugium plus lots of macro algae, and had no mechanical filtration. Eventually I unplugged the protein skimmer. I had low fish loads, obviously.
- I don't know if you have cooling problems, but I did (this tank was in central Texas). I dug a trench by the side of my house and put a closed-loop 'radiator' of sorts in it with thinwall pvc. Tank water circulated through it when the tanks reached a certain temperature. When buried, it worked as a kind of geothermal cooler. I got the idea from a guy in Florida who grew coral in greenhouses and cooled his tanks with a large closed-loop system like this.

I also remember people using Solatubes for some of their reef lighting.

Even with all my little efficiency improvements, when my tank was fully lit with the metal halides on, it probably used more juice in an hour than some of the off-grid guys here use in a day. I think if you somehow tried to take a reef tank 'offgrid', you'd have to put it in a greenhouse in a warm climate, so that the sun was the only light source needed for the tank. Then the main draw would just be a big, high-efficiency pump like the Ampmaster (with a closed-loop cooler as well). In theory, I could imagine, say, 140 watts for the pump x 24 hours = 3.4 kilowatt-hours/day, plus you'd have a few extra small loads (like the calcuim reactor pump, e.g.). Loads like this are possible with solar, but it's already a very big system. Both the traditional reef guys and the off-grid guys would think you were insane!

mike95490 · March 2012

Re: Solar Aquarium Lighting?

High brightness LED's need cooling. 5 watt will need either large heat sinks, or smaller ones with fans. The warmer the LED's get, the less efficient they become.

Generally, the Red and Blue LEDs make up the bulk of gardening LED lamps, and they are all pretty much one color (wavelength). I think there may be 2 colors of Blue. White LEDs are either blue or UV emitters, with a glob of phosphor, mixed to the desired spectrum. Same phosphors as used inside a florescent tube, but just a dab on the LED.

But by the time you factor the drivers/ballasts for the LED's and quantities needed, you will consume as much power overall, as the T-8's . And along the way, you'll find a couple weak LED's that will fail, and need change out. But then you should be on the way to a few thousand house of no maintenance. So - LED's will save replacement labor, but not energy use.

If you want to offset your electric bill, forgo the batteries, install a pure grid-tie, and get a small backup genset.

fust · March 2012

Re: Solar Aquarium Lighting?

mike90045:

The LEDs are actually much more efficient than T8s in "Watts per PAR," but not necessarily Watts per Lumen. Because the LEDs focus on such a narrow (usable) bandwidth of light, fewer Watts of them are needed for the same coral growth as florescent, or even Metal Halide. A 100W LED system is supposed to be the equivalent of a 250W Metal Halide in spectrum usable to the organisms. Not sure how it compares to florescent directly, but it's probably similar. If I'm not mistaken (no expert here), the wattage rating of the LEDs take in to account the heat. They consume the 20W either way, whether by light or by heat. Of course I will have sufficient heat sinks for the job, so they don't overheat and start to dim. I am not using 5mm LEDs, I am using 20W LEDs at $5 each, so I hope you are wrong about the failing LED's! The drivers are about $7 each if you go the one-driver-per-LED route, and convert from 12v to 15v.

About the LED grow lights, There have been significant advances in LED technology in recent years (even just last year!), so if you look at what's out there now you will see that the good ones now have many different specific wavelengths represented, and for different purposes. It was found that just using red-blue would grow plants, but wouldn't trigger specific processes, like flowering, even with a change in photoperiod, which normally would have induced flowering. The plants need some near-IR AND a reduced photoperiod to trigger that. The days are gone of just using "off the shelf" red and blue LED electronics for horticultural applications. You are 100% correct in your description of how white LEDs work, but they are now making "custom blends" of phosphor material to express specific wavelengths, for particular applications. The idea is that you are putting the energy into what you need, and not what you don't. Some blues (like the Cree "Royal Blue") now use this technology, called remote-phosphor (same for florescents, and even tube TVs).

Also, lighting for terrestrial plant growth, while also expressed in terms of PAR, is completely different than what you want in the display portion of a reef tank. If you put an LED grow lamp (or any grow lamp) on a reef tank, you would have a huge algae problem very quickly. Macro algae growth in excess in a tank smothers your corals and other stuff. The thing is that in a reef tank, you are simulating light conditions often meters under water, where the water acts like a filter, so totally different light wavelengths exist down there. But you are doing this in very shallow water, so you have to craft the wavelengths you use. Macro algae usually live in shallower waters.

OK, sorry, I should shut up now. This is neither a lighting nor an aquarium forum!

Maybe the best approach here is to forget about the solar as far as the lighting is concerned. Except wait, I just thought of something:

LEDs in this class run on 13.5-15v, so I wonder if I could just drive them straight from a 12v off-grid system, so no need for a driver? Don't batteries actually put out about ~14v?

Or what about direct-drive? Can I just run one 20W, 14v LED from a 20W, 12v PV panel??? Sun comes up, lights go on? Except I guess I would need some way to keep it from delivering more than 15v. Is that hard to do?

BB. · March 2012

Re: Solar Aquarium Lighting?

LED's need a "ballast" to limit current (i.e., an LED may need 3-6 volts and 1.00 amp drive--The voltage depending on the exact temperature and how much current is needed/allowed for a particular application).

So--Technically all LED's need some sort of "driver" to keep current to a fixed amount (and possible temperature based current limits).

The "problem" with Solar Power Systems is that a "12 volt" system is not really 12 volts... We are used to a 12 volt car outlet having around 12.0 to 14.2 volts during normal operation.

A "12 volt" deep cycle solar/wind/RE system may run from 10.5 (typically 11.5 volts minimum) to 15.5 or even 16.0 volts... Many standard "12 volt" devices are not designed to run that wide of voltage range. They will either fail to operate (typically below 12.0 volts) or can even fail at 15-16 volts (seen during equalization or in sub freezing climates with temperature compensated charge controllers).

This is one reason why I sometimes recommend a good quality 12 volt TSW inverter even when "12 volt" native devices are available... The "extra" losses of ~15% to convert to 120 VAC is made up to avoid the 10.5-15.0+ volts of battery bank. Plus, since the current at 120 VAC is ~1/10 the amperage for the same power and you have 3-5 volts room for voltage drop (12 VDC systems can only live with ~1.0 volt max drop)--It becomes very easy to send power more than a handful of feet.

-Bill

fust · March 2012

Re: Solar Aquarium Lighting?

The LEDs I am looking at are rated at 20W, 13.5-15v, Forward Current : 1400mA ~ 1800mA. The panel I have is rated at 20W, 14.5v, 1.38A. So it looks like it's just shy of enough power to directly power one of these LEDs under ideal conditions, right?

BB. · March 2012

Re: Solar Aquarium Lighting?

It is tough to say... In theory, the solar array will output from 0 volts to ~21 volts and Vmp/Imp optimum power point is ~17.5 volts for a typical "12 volt" panel.

LED's will work nicely if the available drive current is less than 100% (at a slightly lower input voltage to the LED die). However--It does depend a bit on the actual Drive/Ballast circuit as to how it will respond to lower input voltage (i.e., simple resistor; active current limit, was the LED ballast designed for 12 volt DC or AC voltage, etc.).

It is really a pain in many ways--Solar Panels are not "solar batteries" in the way that most people assume (a battery where the voltage is ~12.0 to 14.5 volts and is controlled--for the most part--by the battery itself over a fairly wide current range)... They are actually high impedance Current Sources instead, where the output voltage is really controlled by the load and the available output current is defined by the amount of direct sunlight at any moment in time.

-Bill

westbranch · March 2012

Re: Solar Aquarium Lighting?

FWIW the MR16 LEDs I used at the old cabin were fed directly by the battery, we seldom needed them on so can not say what might happen mid day with hi V. But they worked flawlessly till some of the emitters on some wore out, on others(cheap eBay) the glue let go but they worked till I moved then, the rest were fine... YMMV

fust · March 2012

Re: Solar Aquarium Lighting?

OK, thanks everyone for all the help!

The cheap ebay MR16 route was one I have/am considered(ing). There are 9W whites in Cool White (not neutral white AFAIK), and 3W blue in "standard blue" (no "royal blue" AFAIK), and that would actually work just fine, although not optimal. It would probably work out cheaper, too (excluding lamp failures). The more I think about it, the more viable this looks. MR16 LEDs run off grid. I could add lights and panels and batteries as I could afford it. The balance can be run on AC, probably sticking with the 3 florescent fixtures as well for now. Once I had enough juice, I could retire one of them. I could even make a spotlight area for my anemone. In fact, that cheap-o charge controller even has a 12v output! Wonder if I could use that as just a 12v regulator regulator, and run a few of the MR16's straight from the panel like I was imagining. If that works, maybe I can run a couple of them along with my other insufficient lighting for a "high noon" effect, with high noon being ACTUAL high noon!

I think I have enough to chew on. For $16 for the charge controller, I think I'm just going to get it to play around. That at the least gets me a solar battery charger, which I could then use for power outages (I have an inverter) once I get a proper battery.

Thanks again!

westbranch · March 2012

Re: Solar Aquarium Lighting?

to start, find someone that is going to replace their camper /rv 12v battery and ''learn'' on that first then go out and get a good one... when you have killed the old one... lots to learn

Solar Aquarium Lighting?

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