What to do with all that power ?

[zenpi314]

This last year I have been working on getting some back-up power in the house.

I live in Florida and almost every year we deal with power outages due to hurricanes.

Although a couple of days without power is nothing life-threatening, it certainly is uncomfortable if the temperatures are in the 90's. I started with building a small ametek turbine, but it is really not enough to give reasonable power. So I started on a dual rotor 6.8ft diameter turbine. This is still a work in progress.

Recently I purchased a 20Watt solar panel and installed it in the backyard.









With my limited knowledge of electronics I built a small control panel to manage the incoming power. Currently, it is charging two 12volt batteries. One is 110AH Trojan and the other is a small 20AH battery. It is charging one or the other.

A main switch can disconnect the solar panel. A cheap sunsaver is controlling the input and the output.





This seems to work out fine.

The main problem has been to know what to do with all the energy I'm accumulating (admittedly very little power, but it is expandable;). The batteries are in our shed while I will need the energy in our house. I do not want to lug those extremely heavy batteries back and forth.

The current solution is very not very efficient, but it gives me great flexibility.

I am charging AA batteries from the 12volt batteries. Two chargers, which I can turn on or off, are hooked up to the electronic board.





The charged AA batteries will be used for anything from powering a small lcd tv to led flashlights. I also have 3 24volt computer fans that I am running of rechargeable 9volt batteries. I bought some D cell battery converters that let me change 2 AA batteries into 1 D cell battery, so I only have to charge AA batteries.

So far, I'm happy with this solution. I know it is terribly inefficient, but I can't think of a better way to have backup power. I don't want to run wires all over the house to run 12volt appliances.

If anyone has a better idea, I'm certainly open for suggestions.

Or if anyone sees a mistake in the control panel, please let me know. I don't want to set the house on fire.

When my turbine is finished (hopefully in the next few weeks), it will be added to the system on a separate battery. But that is a topic for another diary.

[scottsAI]

Hello zenpi314,

Yep your right.

OK, how about putting the batteries in a box next to the house. Size it for expansion.

Short heavy cable to bring in the 12VDC power.

In house add a DC distribution fuse box and inverter to power the 120v things your just dying to run. Utility rooms or garage often have the electrical box so put this stuff there?

The cable from the solar panel can be quite thin, less than 2 amps in it.

Have fun,

Scott.

[wooferhound]

It's not to hard to run wires to the house

http://www.fieldlines.com/story/2008/3/4/6303/63451

You say that you want power for the hot days in Florida when the power is off.

You can run fans off of that small amount of power, but don't expect to run an air conditioner with that.

Cool set-up you got. I can't tell if you are charging any big batteries with your rig there. Interesting charging system.

[TheCasualTraveler]

     As a fellow Floridian, here's my take. I originally thought I would make lots of power and partially take my house off grid. OK, I realize now how hard it is to make power and how cheap it is to buy it. None the less like you I want power for outages as well as using it in between times. Here are the realistic things I will be using it for,

DAILY USE,

Attic cooling fans. It's senseless to try to use the power to run the AC but it makes a lot of sense to use it for attic cooling to ease the air conditioners load. I am making 12 volt dc fans for this, no sense losing more power using ac and an invertor. In additon to easing the AC load I plan to gain extra weeks were I don't use AC.

I'm working on a 12 volt pump to intermittantly spray water on the roof to help with cooling via evaporation.

12 volt pumps to circulate water in my solar water heater for pool and hot tub. Hurricane party anyone?

FOR HURRICANE BACKUP, POWER OUTAGES,

With a not too expensive invertor you can power up your computer during hurricane outages (assuming the network isn't down)

Fans again, 12 volt dc. Just enough to survive those hot muggy nights after a storm.

12 volt flourecent lights, cell phone charger etc.

     I always look forward to Hurricane season. Each year on June first all my friends find my Happy Hurricane Season greeting cards in their mailboxs. I don't sweat the storms, I'm prepared. Only 81 days till Hurricane season.

[ZooT]

I wouldn't want to lug a big battery around either....

I think one of the other guys here put his entire PV system on a dolly, and I guess the battery is heavy enough to keep the wind from blowing it over....but the wheels make it easilly portable...

[AbyssUnderground]

I lug a 28KG 90Ah 12v SLA around with me when camping. Its no fun I'll tell you. Thankfully its only from the car to the tent, so <15 meters usually.

[dalibor]

how about small 12 V fridge loaded with beer :-) ?

[Electron Skipper]

Since they actually make self solar powered attic vents, you might consider utilizing those rather than take your power that is potentially useful elsewhere.

Excess power?  How about supplemental heating of water in a hot water tank?  This can reduce some of the grid burden of your appliances.  Pump water into a reserve storage tank?

Maybe rather than looking at the attic fans with your excess, maybe if you are currently running air filters or circulation within the house itself, if they run continuously anyway, they would be more practical.

[ghurd]

"mistake in the control panel".  Not a mistake, but I don't like to use the load terminals to directly feed anything more than a control circuit (relay or optoisolator).

It doesn't take much to fry the LVD part of an 'SS-X with LVD'.  The surge of an inverter can do it before it is even turned on.

I would connect the loads to the battery terminals, or directly to the battery.

The loads shown are OK, but be warned about larger loads or inverters on the LVD terminals.

Some of those coil cords look nice, but are very thin and cause a large voltage loss.  Consider something super-ugly with heavy wires when you start using more power.

Not putting it down.  I like it.  It works, and it's simple.

I like over-kill, such as the 100A/1000A surge switch for a 1.2A panel!

G-

[zenpi314]

Hi Ghurd,

Thank you for the reply.

I'm such a novice that it took me some google searching to figure out what 'SS-X with LVD' means. Duh!!!

If I connect a load to the battery terminals of the SS, how does it protect the battery from draining too low? (besides monitoring it manually)

At what loads should I worry about overloading the LVD terminal?

Would I notice it if the LVD terminal is damaged? (LED not working for example)

Should I connect a relay to that terminal? If so, how?

Sorry for all the questions, but I'm just barely understanding what I have done so far;)

Thanks,

Arno

P.S. What is the best place to connect a voltmeter (one with a needle) to check the battery charge? Since I get different readings depending where I connect it.

[zenpi314]

Thanks everyone for the comments.

The setup is really mainly for backup power. I am such an electricity hawk (AC to battle Florida heat in a trailer, several computers, and many other electrical gadgets) that a 20W panel, or even a 200W panel, would not make a dent in our consumption. I wish it was otherwise, but unfortunately that's reality. A new AC unit would probably save us more than additional solar panels.

it is nice to see what others have done with their 'green' energy. The water on the roof idea seems particularly interesting. Please let us know how it works out for you!

But with all the water restriction in Florida at the moment (and probably even more in the future) it might not be a viable option.

I might be able to partially use the batteries closer to the house option, by splitting up my two batteries. Use one to charge the way I do now, and the other to directly supply for some 12 volt items in the house.

Again, thanks for the helpful comments.

Arno

[ghurd]

The SS-6 with LVD, the LVD is rated for 6A.  I would want to keep it under 5A.

The LVD is almost an emergency use idea.

Most people don't want their batteries below about 12.4V.  Almost nobody wants them below 12.2V.

The battery is 'dead' at about 11.9V.

The LVD doesn't disconnect the load until 11.5V, so it doesn't protect the battery as much as it seems.

Using the LVD to automatically control a load that often cycles will damage the battery in a short time.

The volt meter would go on the SS-6 battery termminals (will not be too accurate while charging or while loads are on), or have seperate wires down to the battery itself.  

I would put a momentary-contact normally-open switch in the wire (MOM-N.O.), push the button and the meter works.

G-