Battery-less solar power system

[DreamThinkBuild]

Hi All,

I briefly tried this and the concept works. It's based off of this patent.

US 6367259 : Battery-less solar power system

https://www.google.com/patents/US6367259
or if your blocked by google
http://www.freepatentsonline.com/6367259.html

With 6x3000F ultracaps in series(500F), 630watts on array one and charge controller I'm able to charge them to 14.4volts then run a 1000watt heater element till the inverter low voltage alarm of 10.5volts kicks on, stop go back to charging to 14.4, then running. Right now I don't have any switching just did it by hand to test the idea quickly. The nice trade off with using caps is they charge fast compared to hours like a battery and dump amps quickly for electric motors (instant torque).

Going by the patents math.

Icharging=(500F*(14.4-10.5)/(630/18))
         =(500F*3.9v)/35a
         =55.7 seconds

Irunning=(500F*(14.4-10.5))/((1000/12)-35a)
        =(500F*3.9v)/(84-35)
        =1950/49
        =39.8 seconds
       
So a full charge/run cycle = 95.5 seconds or 1.59 minutes
In 1 hour it can make 37 pulses into the heater element.

It charged slower on my test since I drop amps on the charge controller, inverter and wire losses. A more direct approach like the patent shows would give full amps to the caps and output. Balancing (lowering) the capacitance would also increase the pulse repetition. A heater element also is not really the best example. A large electric motor with a heavy load could double over as a heater, just capture the waste heat.

What would be the ideal storage for maintaining batteries for 8 hours overnight? Something that can generate maybe a constant 18watts overnight 18vdc@1amp. This would require two solar setups, one regular, then one small for just charging caps and running a storage system for overnight. Maybe pulse running a DC winch motor throughout the day lifting a heavy weight then letting it slowly drop overnight hooked to a low rpm wind alternator. Any other ideas?

[mscoffman]

A couple things; inverters usually have more lower voltage range then you would think. Many allow adjustment
below 10.5VDC They have an alarm and then cut off to prevent a vehicle acid/lead battery from draining too
much then not being able to start the vehicle. You do not have that problem, how low depends on the inverter model
number. If you ever expect to have acid lead service then don't change the lower limit. Also the alarm signal occurs before
shutdown of the inverter. If you can gain access to the signal then install an optoisolator, then a remote computer
control.

There are two inverters that are designed for 6VDC and 8VDC batteries.

Get to understand how latching relays and contactors work. They prevent relay coils from drawing high currents
during the whole period that they are on. They have two coils that they need pulsed for under one second then latch.
TE Tyco Inc. makes some inexpensive high current ones.

Relays generally have two maximum current specs, one when they switch on or off, another when current is flowing
you can put in place high current standard shadow-relays that does the high current switching while the holding-
relay never has to switch the current.

The classic solution to having to do charge and discharge cycles is to have two banks so while you are discharing
one bank you are charging the other.

I don't consider there are any better methods of storing energy then by lithium batteries. Hydrogen gas (non-hho),
maybe commercial flywheels.

If you had the right property set-up compressed air looks interesting. If you could compress air using utility power
at one am when a heat sink is cool then use an air motor to a generator to decompress it at one pm. when
a heat sink is hot then feed some back into the grid to get your meter backward you would get additional energy, then
set it up so that the generator would run the compressor and "chase" empty air tanks then see how long one could
get this system to go on like this.

:S:MarkSCoffman

[DreamThinkBuild]

Hi Mark,

Thank you for your insight.

I'll read up some more on the latching relays and contractors.

If you had the right property set-up compressed air looks interesting.

While space isn't an issue it's mainly town code that is a pain in the butt around here.

I have two solar setups both are not grid tied. One is 630watts@1.8kwh which is used for running led lighting, fans and laptop, light duty stuff, the other is 1.26kw@12kwh which is used for running heavy loads AC(during day), fridge, freezer etc. At night a lot of non-essential stuff is powered down so I'm looking for an alternative to maintaining a night time charge on the system.

[e2matrix]

DTB,  Are you aware of Bill Alek and Auroratek.us ?   If he has what he claims it might be exactly what you are looking for.   His SmartPak tech claims to recharge 12 volt LA batteries from the very battery it is charging.   Up to 20 amps charging current.   He's been at this device a long time and I think he may really have something although the usual people here are trying to fault his methods and claims.    Take a look at the Self sustainable battery charger here:  http://www.auroratek.us/PRODUCTS.html     which is supposed to be available in a month or so. 

[DreamThinkBuild]

Hi E2Matrix,

I've seen Mr. Alek's device on his website but don't have enough real world data on it. The concern also is if its safe for batteries over the long run. It's something I will keep an eye on.