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Do I really need batteries for a solar energy system?

 
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Rachel Brylawski wrote:

Brian Maverick wrote:
I too would echo LiFe batteries as the best resource for energy storage.  But cost wise, you can take a spread sheet see how long an RV/Marine battery Deep Cycle group 27 battery would last and it's replacements vs. the LiFe (lithium-Iron) batteries.  It's almost a wash.  The real trick is, having the right balance of capacitors to the solar setup in the system. The caps would help with heavy load startups that taxi the batteries.   Taking that load off really extends the RV/Marine Gel cells battery life.



Interesting. I don't know much about capacitor size, since we don't use AC energy and don't have to worry about the start surge. To clarify, we use NiFe (nickle-iron) batteries, not lithium iron, and run our lights and charge devices with 12 volt DC electricity. (Using an "Iron Sun" kit, available here -- http://livingenergylights.com) We reduce the load on the batteries tremendously by powering everything else "daylight drive" (running the motors while the sun is shining using high voltage DC from our main PV array), not pulling the energy through an inverter and battery bank at all.



Ah, got it.  You are using the original type of the Edison battery design then.
https://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

I mis-read that for the modern variation of the battery like this,
https://ironedison.com/lithium-batteries

The combination of the LiFe are becoming cheaper to make and much more plentiful as EV vehicles and other hand-held devices are using the technology.   The huge advantage is the weight.  The nickle types are HEAVY and the Lithium are lite.  

For the link you had provided, the cost is interesting.  It's too cheap.  Sure the shipping is up there, but the weight is affecting that.  My only concern is the LED bulbs; No rating if they are health safe as in 3000K (kelvin) or less.  If they are, then it's a no trainer to snag a kit or 2 for 12VDC use.

I do like the other posting here about no battery needed.  Capacitors with a voltage regulator and a resistor or two would replace a battery for all night long LED lighting.
 
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Brian Maverick wrote:
Ah, got it.  You are using the original type of the Edison battery design then.
https://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

I mis-read that for the modern variation of the battery like this,
https://ironedison.com/lithium-batteries

The combination of the LiFe are becoming cheaper to make and much more plentiful as EV vehicles and other hand-held devices are using the technology.   The huge advantage is the weight.  The nickle types are HEAVY and the Lithium are lite.  

For the link you had provided, the cost is interesting.  It's too cheap.  Sure the shipping is up there, but the weight is affecting that.  My only concern is the LED bulbs; No rating if they are health safe as in 3000K (kelvin) or less.  If they are, then it's a no trainer to snag a kit or 2 for 12VDC use.

I do like the other posting here about no battery needed.  Capacitors with a voltage regulator and a resistor or two would replace a battery for all night long LED lighting.



Brian, I appreciate your response.

You are right about the weight and bulk of NiFe batteries, which would definitely be a disadvantage in mobile applications -- you're never going to find them inside a smart phone! But for stationary household use, this isn't really an issue. Lithium batteries make sense for hand-held devices. But for the larger battery capacity of an off-grid system, the cost of lithium batteries is steep, seems like overkill to me. I just followed the link you gave for LiFe batteries and whoa! That's pricey! Almost $37,000 for 100amp/hr? I guess the only comparison I have is our 100 amp/hr NiFe kit, for $2,400, less than a tenth the cost (https://livingenergylights.com/product/iron-sun-homestead-kit/)

You said these NiFe kits are "too cheap." I'm curious to hear what you mean by that. Usually I hear the opposite critique of NiFes, that they are too expensive. I can tell from your post that you know way more about the different batteries and off-grid designs available out there than I do. In all honesty I would love to hear more about what makes these kits "too cheap."

I don't know about the kelvin rating of the 12v LED light bulbs, I'll try to find out. I do know they are only 3-7 watts, and we've never had any safety issues with them in the past ten years. We had an issue with the original kind of LED bulbs we bought that they would burn out if you left them on when it's bright and shiny out (because of the unfortunate positive feedback loop with LED bulbs), but it was never dangerous, just inconvenient to have to replace them if we were careless. These newer ones can tolerate being left on during the day and voltage swings much better and are much more durable, though it's still good to turn them off during the day.
a
UPDATE: I looked into the kelvin rating more and see this refers to the color of light emitted. I had interpreted your question to refer to electrical safety, but now I see you said "healthy" -- were you referring to the potential impacts of blue light? They are making LED bulbs in various color spectrums now. We tested a bunch of different 12v DC LED bulbs and found two that we were happy with. One produces bright white/blueish light and the other produces warmer yellow light. We only got a few of the latter "Neoclassic" bulbs to test them out, they don't come in the "Iron Sun" kits or a la carte yet (https://livingenergylights.com/product/iron-sun-kit-accessories/), but hopefully in the next couple months this option will be available for folks who would prefer a warmer light spectrum.

Can you explain more about this capacitor and resistors set up you referred to, which could eliminate the need for a battery altogether (at least for lighting)? Very intriguing to me. How well do you think it would hold up in a cloudy spell? What about charging electronics?

Thanks for sharing your insights.
 
Brian Maverick
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Rachel Brylawski wrote:
Can you explain more about this capacitor and resistors set up you referred to, which could eliminate the need for a battery altogether (at least for lighting)? Very intriguing to me. How well do you think it would hold up in a cloudy spell? What about charging electronics?

Thanks for sharing your insights.



Well, batteries for one are a type of capacitor.  Batteries can store more energy for a longer period of time.  Capacitors have the advantage of storing much higher voltage and less amps.  Think of capacitors as store more of static power.  Lots of punch, but fizzles out in a much shorter time.   Here's at least a quick overview. https://en.wikipedia.org/wiki/Capacitor

Capacitors can retain a charge, the bigger they are, the more power they can retain.  Much like a battery.  BUT, more deadly to ones health should you touch both ends or make contact on a polarized one.  These have enough power like a fence zapper, but higher to stop a person's heart.  

Batteries like to be slowly drained for providing power to have long life.  Capacitors will dump there power almost instantly.  To help control the capacitor power dump to be drawn slower, resistors or a blocking diode come in handy.  These will limit the amount of power being dumped.  Thus, to run a few simple LEDs or LED lamps, you'll get many hours or days with them without using a battery.  As for capacitors being able to charge things, nope, that isn't likely.  Remember, these do not carry enough Amp power.

Think of Amps being the current of a running river.  And think of voltage as how high the water in the river reaches.  Batteries have great current for Amps, but in time the water height in the river keeps dropping.  Capacitors are the other way around.  They like the water high, but the current flows very slow (just like a static shock).

Here's a good video of making a bank of capacitors into a mini battery.  Due note, the person in the video believes you have some electrical understanding.  For example when the video starts out, he points to the side of a capacitor and the longer wire lead coming out.  Right there he's stating these are POLARIZED capacitors.  Very important to know.

Super Capacitor | How To Use Capacitor As a Battery
https://www.youtube.com/watch?v=Gkl8zyA11ks

Now, this video was a demonstration.  The concept will work for components of any capacitance.  For a longer run time and more LEDs, greater capacitors and a resistor(s) may be needed.  LEDs are funny little things, too much power sets them off like popcorn!  They HATE Amps, but love low voltage.  Thus, capacitors and LEDs really get along with one another.  That's the reason in the video the cap battery like system powering the LEDs had no other components.

Now, going BIGGER, one can then replace their car battery altogether.  Why?  Because a vehicle has an alternator that generates power while the vehicle runs. It will fill the bank of capacitors with power too. Amazingly, the person runs their car radio with all the speakers on just from the bank of capacitors for a mere 30mins (no alternator used), then starts the car.
https://www.youtube.com/watch?v=z3x_kYq3mHM&feature=youtu.be
 
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Location: SE Indiana
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I know very little about about solar power or electricity in general. I have wondered if it might be possible to store solar energy as heat rather than electricity. Might a person spend more money on more panels, none on batteries and just convert it directly to heat stored in a thermal mass. Similarly in summer, might it be possible to to run some kind of chilling apparatus and store the lack of heat in the same thermal mass? Eliminate the learning curve and a good part of the expense all at once? Or is this idea just goofy?
 
Brian Maverick
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Mark Reed wrote:I know very little about about solar power or electricity in general. I have wondered if it might be possible to store solar energy as heat rather than electricity. Might a person spend more money on more panels, none on batteries and just convert it directly to heat stored in a thermal mass. Similarly in summer, might it be possible to to run some kind of chilling apparatus and store the lack of heat in the same thermal mass? Eliminate the learning curve and a good part of the expense all at once? Or is this idea just goofy?



Mark,

Your idea is not goofy, just a little mis-placed.  You can store solar as heat with a solar heating collector.  It's on a 'similar' scale to the solar food dehydrators mentioned here.  And at times about 2/3rds the cost of a PV panel.

Now, to really help to INCREASE the solar heat, a fresnel lens is like having a turbo charger to the heat gathering.   You can make a small version at home with the fresnel lens sold at the Dollar-Tree for only $1 each!  These are about 8x6 or something close to that size.  They sell them as plastic sheet magnifiers to read books and newspapers quickly.  If it gets flexed just a little, you can turn that lens into a fire starter as the sun's rays will burn loose leaves and twigs.

To store solar heated energy, it can be in a fire, heated bricks, heated liquid, etc. One can even boil liquids with a solar collector.  Just be very careful.  Boiling liquid can then be converted into ELECTRICITY too. Harness the steam power!  And with a little steam engine, it will in turn run a belt to an alternator.  This will give you 12VDC to charge BATTERIES.

So as you can see, one does not need a PV panel to get electricity and know all the science behind solar PV panels, blocking diodes, charge controllers, wiring and hook-up connections.  

For cooling, all I can say is, start a root cellar.  It's the most cost effective way and more reliable way to keep things cool.  The deeper you go or into the side of a hill the better.  45F to 60F is the range depending on the summer growing zone you reside in.  Geothermal is the BEST to lower temps in the summer hands down without relying on electrical generation.

Brian
 
pollinator
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We had solar panels in the 70's, just not PV, the energy was stored in hot water, but it didn't work very well. I suppose this is why the industry moved away from this.
 
gardener
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Solar hot water is very effective and efficient, and cost-effective; just not for electric use.
 
pollinator
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Glenn Herbert wrote:Solar hot water is very effective and efficient, and cost-effective; just not for electric use.



Just remember that it is a breeding ground for legionnaires disease so separate the heating from actual use. For example most solar water heaters these day use glycol in the solar heating and exchange to water that goes to the house. You loose a little in the exchange but gain a lot in staying alive.
 
Stacy Witscher
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We have a solar hot water heater on one of our houses. It uses glycol and has a backup propane water heater. This also heats the hot tub.

The solar that was on my childhood house used water that heated a large tank, that then somehow provided heat for the house through wall units called chillchasers. It didn't work well at all. Thankfully, we lived in a mild climate, that rarely needed heat.
 
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Rachel Brylawski wrote:. (Check out this "Cabin Iron Sun" kit for $300, which includes the solar panel, NiFe battery set, lightbulbs, adapters, etc: https://livingenergylights.com/product/iron-sun-cabin-kit/)



Hi,

I looked at the link.
That Cabin Iron sun kit is actually very interesting.

For a low price it give you the opportunity to play with Nickel Iron batteries. Without the need to shell out multiple $$$$ for a big set.
Or the hassle to import a nife battery set from China. It's doable to import them yourself, but not for such a small order.

Reminds me bit to the lead acid batteries and charge controller kits you can find everywhere.


Greetings!

 
Rachel Brylawski
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Steven Di Maira wrote:

Rachel Brylawski wrote:. (Check out this "Cabin Iron Sun" kit for $300, which includes the solar panel, NiFe battery set, lightbulbs, adapters, etc: https://livingenergylights.com/product/iron-sun-cabin-kit/)



Hi,

I looked at the link.
That Cabin Iron sun kit is actually very interesting.

For a low price it give you the opportunity to play with Nickel Iron batteries. Without the need to shell out multiple $$$$ for a big set.
Or the hassle to import a nife battery set from China. It's doable to import them yourself, but not for such a small order.

Reminds me bit to the lead acid batteries and charge controller kits you can find everywhere.

Greetings!



Exactly our thinking! Except, the nickle irons are a lot more durable and long lasting than lead acid. And important to note that the Cabin Kit is REALLY small, just 10amp/hr, a fraction of most battery sets. Not going to run an inverter, larger motors. But plenty adequate for lighting with efficient LED bulbs, along with running a small fan and charging electronics when there's been decent sun. Which is all you really need batteries for, since, there are lots of other cool ways to meet other energy needs, as folks have been pointing out in this thread (solar water and space heating, pumps or pond aerators run right off PV panels, etc.) Yey for site-specific, permaculture approaches to designing Zone 1 energy systems, rather than just thinking of it as a bulk commodity that has to be supplied from one central source. (Battery bank and/or power grid.)
:)
 
Joel Salatin has signs on his property that say "Trespassers will be Impressed!" Impressive tiny ad:
Devious Experiments for a Truly Passive Greenhouse!
https://www.kickstarter.com/projects/paulwheaton/greenhouse-1
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