Solar energy for when electric is out

[Rybren]

If you want to go solar, you'll want to start at the beginning: what load do I want to support and how long do I want to support it?

You'll essentially be running an off-grid style setup (and yes, I do have one running at my summer place - I'm completely off the grid). Here's a rough plan:

- Grab a kill-a-watt meter and measure the consumption of everything you want to run off the batteries
- Use this number to calculate how many amp-hours you'll need to get from the battery bank.
- Multiply the amp-hour total by the number of days you'll want the back-up to be good for
-Double this value (you don't want to run the batts below 50%)
-This will provide you with the required size of the battery bank (amp-hour capacity)
- Calculate how much energy you'll require from the solar panels to recharge the batteries (you'll need to produce about 10% of the amp-hour capacity of the battery bank)
-Use true Deep Cycle batteries rather than the 12V marine style. I like to use 6V golf-cart batteries.
-Get a true sine Inverter to provide AC power to the tank. Don't oversize it as the bigger the inverter, the higher the tare load on the system
-Get an automatic transfer switch so that the house will switch to solar in the event of a main power failure.

I think you'll find that going this route will be very expensive and that you'll be better off grabbing a small genny and some battery-powered airpumps instead

 

[thunderdood]

Have you looked into a UPS (uninterruptible power supply)? We use several at work to keep servers online if there is a power outage.

 

[bif24701]

Have you looked into a UPS (uninterruptible power supply)? We use several at work to keep servers online if there is a power outage.

A UPS is inefficient because of the conversion of from DC to AC back to DC. A a car battery would have far more run time.

 

[justingraham]

Yea Thera is no easy or cheap way of doing this I don't think. Pretty much every way that is cost effective you would have to be home to turn something on. But I will think of something that I promise you

 

[saltyfilmfolks]

Yea Thera is no easy or cheap way of doing this I don't think. Pretty much every way that is cost effective you would have to be home to turn something on. But I will think of something that I promise you

I disagree . Poke shmebay. With the right switch it should work. You could in fact use Aaurduino so I know there the right on is out out there. Apex would work too if you were a programmer.
I did the research some time ago but I figured it out. It wold have been $1000 I didn't have at the time.

My tanks are now pretty much all D.C. Now though so I've been looking at 24v D.C. Battery backups to do it on the cheap but but I have to find a different switcher now. And I'm not a nerd so it takes me while to research. But that just dropped the price and it's just the panels holding me up.

I would only leave my lights on AC as there are the biggest draw in the system now.

 

[saltyfilmfolks]

Maybe these guys. http://absak.com/index.php/

 

[Rybren]

Some of those panels aren't too bad price-wise. You should pay about $1 per watt for a panel.

If we look at the 250W @ $250, the max voltage is 30.3V and max current is 8.26A (30.3 x 8.26=250.xx W). It would only produce close to this amount for a short period of the day, right around solar noon, and only if the panel is oriented properly. At any other time time, the panel will produce less power.

If used to recharge a 12V battery bank with a PWM charge controller, the max power that you could expect to be available would be roughly 123W (14.8v charging x 8.26A), the rest would be wasted. If you use an MPPT charge controller (more $$), then it would convert the excess voltage into current and you could achieve close to 250W.

With this same panel, the voltage would be too low to charge a 24V battery bank ( inefficiencies and voltage drop through the charge controller would reduce the charging voltage too much below the required 29.6V, so you'd need 2 panels. However, with 2 panels and an MPPT controller, you could easily charge a 200 amp-hour 24V battery bank.

 

[Skydvr]

The 50% discharge rate is for regularly cycling lead acid batteries. Discharging deeper than that shortens the life cycle. You can think of it in full discharge cycles. Say a battery is good for 500 cycles down to 80% discharge (80% is okay for lead acid occasionally but severly shortens the life). If discharged to 80% every day, that would be about 1 1/3 years the battery would last with the capacity severly dropping off towards the end. Limiting the discharge to 50% will get you significantly longer; over twice as long. The relationsip isn't anywhere near linear and there are a lot of factors that go into it such as temperature, type of charger, charge modes, chemistry, etc.
Lithium technologies last around 5000 cycles discharged to around 80%, but are much more expensive and require more complex charging cycles, but they are maintenance free.

There are fairly simple and inexpensive ways to accomplish what you are looking to do, but you will pay a lot in wasted electricity. Finding a ballance between upfront cost, electricity usage, and potential cost and loss of life due to power loss isses compared to risk of power loss over the short and long term also has to take into account lifestyle choices such as travel and at what time of year you travel.
I'd say in general, the average home reef tank doesn't justify the cost of a dedicated system that automatically switches on to support only the tank for an area that is at low risk of losing power (risk of severe weather) and has a robust power distribution network (well maintained). Europe with predominantly underground service rarely sees power interruptions due to storms, but they are typically dense urban areas. A rural US town in the North East where the power company doesn't trim back tree branches around the suspended power lines and just constantly patches breaks in the lines instead of cutting back damaged sections and replacing sections of damaged lines will have power losses every time there are strong winds, heavy snow, ice storms, etc. That case could justify the cost of a backup system tied in with the fridge along with a mechanically operated gas water heater and circulation pump for heat.

As much as I despise consumer grade generators, that may really be the way to go. Something that runs on natural gas if you have service or propane (as those are more stable than gas or diesel long term considering the infrequency it should run) with an auto start and transfer switch would be good if you travel a lot and could be set up to run the tank, fridge, and heater to keep pipes from freezing in the winter along with any other vital loads you might have. Otherwise a basic generator, a couple of gas cans, and some Sta-bilb should give you peace of mind (cycle the gas in lawn equipment and snowblowers if you have them to keep the fuel fresh).

Now, if you had a 10,000 gallon tank, a solar backup system with a lithium or supercapacitor storage system might be a viable option.


The ideal way to approach the problem with sustainability or renewable energy sources in mind is to look at a larger system that will serve other functions beyond just supporting your tank. A system that allows you to run off grid with a storage system and a fairly unnecessary grid tie-in to offset extended poor weather or to make the town/city/state happy if necessary would be one route.
Or you could just start a crazy breeding program with rare/endangered fish and coral or start collecing super high end coral and run a lot of tanks to justify the cost ;P

 

[ZAB]

Tunze makes a power switch that you can hook up solar panel along with inexpensive battery tender ... along with solar panels. ....bulk reef sells battery power swithe approx 50.00....also saw on American reef channel on u tube...hope this helps

 

[Desmo996]

With hurricanes potentially enroute, I'm finally getting serious about this. So if/when I have to bug out, my thought is to put a solar panel on the outside of the hurricane shutters, connecting it to a voltage regulator & deep cycle 12V battery. Then "simply" connect my two Tunze 6045s just to keep some flow.

In the grand scheme of things, the corals can survive without light for a week or so. So I think my concern needs to be some type of flow and perhaps evaporation after a week. And if we're forced to evacuate longer than that... everything is likely a loss so a reef tank is The least of my problems.

Anybody have a similar setup? Thoughts?

 

[Desmo996]

"...also saw on American reef channel on u tube...hope this helps

That video was exactly what I was looking for, Thanks!

I think I'll do some web searching for the auto power switch... There's only about $5. worth of radio shack parts in there. Since I've got the ability to make my own I may try unless Irma comes to us, then I don't have time.

 

[ZAB]

Ecotech marine Vectra water pump can be hooked up to battery back up....The tunze safety connector will switch on to battery back up as soon as power goes out....and if you have a battery tender it will keep battery charged....saw on amazon some recargable batterys for about 35.oo and would be comparable to bbku.that ecotech sells