Solar power is continuously gaining momentum and popularity. There are now solar chargers designed to power cell-phones, cars, laptops, etc. The solar charger harnesses energy form the sun and stores the energy within its battery for later use.
Typically, a solar charger can hold on to its charge for up to a year. The advantage to using a solar charger is that it eliminates all of those unnecessary, bulky chargers for every electronic device.
It may be difficult to choose between the best solar chargers because there are a lot of great models out there that basically perform the same functions. Upon being fully charged, the solar charger can fill a cell-phone’s life twice or play up to twenty hours of music.
Our top market selection includes:
- Go Power! GPDL-20 20-Watt Self Regulating Unbreakable Solar Module
- Sunforce 60-Watt Solar Charging Kit
- Brunton 26 Watt Foldable Solar Array
- HQRP 20W Mono-crystalline Solar Panel
Solar battery chargers 101
Keep in mind that Your panel will produce 100% full wattage output when placed on direct sunshine
Before buying a portable solar power system, it’s good to answer these questions:
- How long would the solar panel take to charge a 12 volt battery?
- What’s the ideal wattage for a solar charger?
- How can I control if it works fine?
- Will it fry my battery?
Most models have an illuminated LEDs that lets you know the panel is charging. Other have a built in controller to block the charge when the battery is full.
When You buy one, You’ll get quick connectors like cigarette lighter adaptors and battery clamps.
Choose the right solar recharger
To explain in further detail about the conversion, basically an hour of sunshine will equal about an hour of music, or 25 minutes of conversation. The batteries in most solar units last up to about a year, and the charger works with numerous gadgets: Bluetooth, iphone, games, digital cameras, etc.
The charger is extremely light and easy to transport making it optimal for travel purposes.
The General rule to calculate the average charge time:
Take Amp/hour rating of the battery and Divide by the charger rating (in amperes) and then add about 10% for the extra time to top off the battery
I.e. Assuming You have a typical full size auto battery, it is about 50 amp hours.
To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger You’ll need:
- Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
- Calculate the division: 50 amp hours / 1,25 ampers = 40 Hours of direct sunlight
- Add 10%: 4 hours
A 15 watt charger is great for vehicles such as cars, boats, ATV’s, even electric fences. 7 watts are perfect for laptops and camcorders. A 2 watt charger is perfect for cell phones, ipods, and smaller cameras.
There is a formula to help describe the way solar energy works: the output for solar energy is described as watts. The wattage can be understood by multiplying the voltage by the amperage.
More specifically: volts x amps x watts = / e.g. a six volt 30 watt solar panel measuring ten by 22 inches has a voltage of about 8.55, and amperage of 1.75.
One can determine the correct amount of wattage needed based on how much each electronic device expels.
Solar Battery Controllers
In most case a solar charger controller is highly recommended. The Solar Controller will continuously monitor the charge and cut it off when charging is complete.
It helps in:
- Preventing overcharge
- Improve charge quality
- Prevent battery discharge in low or no light conditions.
Some solar panels are made with blocking diodes pre-installed they prevent battery discharge during low or no light conditions.
Once connected, you can charge your 12-volt battery nonstop for days without damaging the battery.
Inverters
Inverters turn DC (Direct current) power into AC (alternate current) power, the type of current that powers everyday appliances.
Final Suggestions
There is no need to buy multiple solar chargers for each electronic device owned, so invest in one with the best quality. If the solar charger is needed to power a lot of devices frequently, makes sure to buy an additional panel at about fifty dollars to ensure the maximum access to available sunlight; this panel allows for powering two laptops at once, and it should feel good to know that the electronic devices are functioning on renewable energy.
For cars it makes sense to purchase a solar charger that sits on the dashboard and soaks up the sun. These are not designed to jump start the car battery, but rather to keep the existing car battery at full charge and functioning.
Basically, if used properly it can extend the battery’s life, which of course saves money in the long run. Therefore, when individuals use many gadgets by plugging them up to the cigarette lighter, the solar charger helps against stress and fatigue that is placed on the battery.
Of course it is still possible to find one solar charger that supplies power to all electronic devices, including a car battery. As mentioned previously, there are many really good choices out there, so investigate properly, ask professionals which best fits their needs and enjoy the fact that you are participating in the usage of renewable energy, an environmentally wise choice.
Our top market selection includes:
{ 91 comments… read them below or add one }
i would like to ask about time needed t discharging a 100 amperes per hour when a 60 watt of dc motor connected to the battery
Do You mean a motor like this? http://www.samedaymusic.com/product–TCHPW60
how many 108 watt solar concentrator panels are needed to charge 120 12 volt batteries
Albert,
It depends on the Ampers Hours of the battery.
Have You tried for a bigger wattage?
108 Watt is good for 1 battery (i.e. for a car) and could charge it completely in 8-6 sun hours.
Enrico
I purchased a 1.8 watt solar panel charger to maintain my truck battery through the winter. I hardly drive it in the winter and the temperature sometimes dropes down to -30 to -40C during the night. Would it hurt the battery if I left the solar panel hooked up to the battery all the time.
No Gord,
You’ll need to buy a solar charge controller.
Have a look here:
http://www.12voltsolarpanels.net/guide-buy-brunton-solar-controller-12volt-battery-charge-monitor
Thanks for the comment!
Enrico
what make of solar charger would keep my car battery,mid range car,charged up,whilst I am away for 3 to 6 months,one I can leave plugged in to the battery,safe to leave,I could only leave it on the inside of my flat window, whichh isnt fully south facing.
Dear Dee,
I suggest You to buy this:
ICP Sunsei SE-1500 Solar Trickle Charger
Have a look here
Let me know
Enrico
i want to put power to my shed,how many 15 watt panels andhow many 12 volt batterys will it take to keep a good power supply there? 2 100 watt lights and 1 radio
It depends on the time your devices will stay active, the location where You are and how much You would spend.
Please provide me more info.
Thx
i am wondering if anyone can help me, i have a project which is is a solar panel that is going to charge up a 6V4.2AH/20HR battery. this is all new to me and am wondering how long it will take a 6 volt 1 watt solar panel to charge up my battery…
if u could help plz send me a email thanks…
You can follow this general rule:
To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger You’ll need:
1. Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
2. Calculate the division: 50 amp hours / 1,25 ampers = 40 Hours of direct sunlight
3. Add 10%: 4 hours
Result: Totally, with a 12 Volt solar powered car battery charger You’ll need 44 hours (nearly 2 days of sunlight) to charge a car battery with a 12 watt solar charger….this mean 7 days to full charge a dead car battery.
I’m looking for a solar panel that, when the sun is out, will drive a 2 amp 12 volt water pump.
Any suggestions?
Dave
Dear Dave You can hav a look here: http://www.12voltsolarpanels.net/basics-solar-power-systems-produce-electricity
It’s a guide to calculate the power You need with a solar panel.
Thx!
I have a uni-solar 32 watt panel with controller woked great for several years now my rv batteries discharge when sun goes down I checked output seems to be good should I add a blocking diode inline and if so on both + and
- ? thanks wayne
Yes a blocking diode could be a good alternative.
Have You tried to install another trickle charger with a solar controller?
I want to solar operate my laptop. What do I need to buy?
Robin You can have a look here:
http://www.12voltsolarpanels.net/buy-coleman-solar-18-watt-12-volt-deep-cycle-battery-charger
i have a 1.4kv home ups and two 12 volt tubular battery 130a…i would like to know as to much pv module will be required to charge this ups ?
I am installing an electric brake into my car that I tow behind the RV. This brake runs off the car battery, being plugged into the 12V outlet. Every two times the brake is applied, the battery draw is 10.5 amps This is used to run a small air compressor used to fill a small air cylinder inside the brake. It takes about 1 minute or less to fill the cylinder. If I use a solar panel hooked into a 12V outlet connected to the car battery (my car has 2 outlets), what size solar panel would I need to keep the car battery charges?
Dear Becca,
You can have a look at this comparison chart:
http://www.12voltsolarpanels.net/solar-chargers-comparison-chart
If you look for a trickle charger You can find something useful.
I built a 16 volt, 5.0 amp solar panel and am using a 1500 watt Cobra inverter. I am charging a 12 volt AGM deep cycle battery. I seem to only get about one hour burning one 17 watt cfl and then the inverter beeps and goes out. This is the second inverter I’ve tried so I’m wondering where I’m going wrong in my system. Is a 16 volt panel too much for a 12 volt, 33amp hour battery? What else should I be doing to get more life out of this system?
Have You used a solar controller?
I want to puchase a solar powered charger that I can charge the battery (12-volt)to my boat,and not be concerned with over charging it,is there one that would automatically turn off when the battery is fully charged, most of the people I’ve talked with locally seem to think I don’t know what I’m talking about, surely it’s not because I’m a woman, I need to find the answers for two reasons, I want to keep my boat ready to go w/o worrying about overcharging, and I want to inform these local guys ,it can be done by a WOMAN!!!!
Sure Sherry,
All You need to do is to buy also this Solar Charge Controller:
http://www.12voltsolarpanels.net/guide-buy-brunton-solar-controller-12volt-battery-charge-monitor
I have 2 panels that produce 22 volts each. What do I have to do to make these panels charge my boat batteries.
I need to know the Amp/H of your panels and Your boat batteries.
Do You think You’ll use the panels to charge or to maintain your batteries?
Hi,
I want to power a cabin, by using 80 Watt solar panels, and AGM batteries rated at 100 AmpHours.
My maximum load will be no more than 1200 Watts.
I would like to be able to supply 75% of my maximum load for 6 hours per night.
How many 80 Watt panels, and how many 100 AmpHour 12 Volt AGM batteries will I need, if I use a 1200 Watt inverter?
Thank You
To calculate the wattage of the solar charger you’ll need to know the Amp/hours (Ampere per Hours) that your battery store.
To calculate the average charge time:
Take Amp/hour rating of the battery and Divide by the charger rating (in amperes) (*) and then add about 10% for the extra time to top off the battery,
(*) “Watt = Ampere x Volts” “Ampere= Watt/Volts” “Volt= Watt/Ampere”
I.e. Assuming You have a typical full size auto battery, it is about 50 amp hours.
To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger You’ll need:
1. Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
2. Calculate the division: 50 amp hours / 1,25 ampers = 40 Hours of direct sunlight
3. Add 10%: 4 hours
Result: Totally, with a 12 Volt solar powered car battery charger You’ll need 44 hours (nearly 2 days of sunlight) to charge a car battery with a 12 watt solar charger….this mean 7 days to full charge a dead car battery.
I think you misunderstood my question.
As I stated in my OP, I want to use 80 Watt panels and 100 Amp Hour batteries.
I want to know how many panels and batteries it will take to supply a 900 to 1200 Watt load for 6 hours per night.
I know that the most I can put into any 12 volt battery at one time is 14.5 Amps, any more will damage the batteries.
If I have several 80 Watt panels I’ll have to use a charge controller to reduce their total Amperage down to the 14.5 maximum charge that I can send to the batteries.
I believe it will take approx 7 hours to charge the batteries.
The part I don’t understand is how long those 100 Amp Hour batteries will supply a 900 to 1200 Watt load.
For the sake of simplicity, let me ask you how long one 12 Volt 100 Amp Hour AGM Battery fully charged will last with a 900 Watt load on it?
Of course I’ll only be draining the batteries to about 50%, but just to answer the question of how long the battery will last with a given load applied…
How long does it take a 900 Watt load to drain a 100 Amp Hour battery?
Ken here a nice quote I’ve found here:
http://www.cruisersforum.com/forums/f14/inverter-and-alternator-questions-14174.html
Basic Ohms law. Amps X volts = watts. So in round numbers you need 10 amps @ 12 volts DC to make 1 amp in 120 volt AC plus the penalty paid for the conversion. To run AC appliances check the watts required or the amps and do the math.
1800 watts of AC power is going to drain those batteries dead as a stone in short order. That means 150 amps DC to make 1800 watts AC! If you take the amp hours from the battery ratings and divide by 50% that will give the amount of power you could drain the batteries and not trash them fast. If you drain a battery dead you will have to replace them a lot sooner than if you drained them only half then recharged them fully.
It’s a total picture as noted by Sullivan. What you take, you need to give back. It goes out a lot faster than it goes back in. Batteries don’t accept charge quickly for long periods. When they are low they can take a lot of amps in but as they recharge more they can’t take as many amps as fast. Suddenly the 50% changes to 40% as the last 10% is a lot longer charging time at a lower rate.
To fix this you need more batteries plus the ability to charge them 100%. Normally, you don’t run a fridge “occasionally”. They generally run a duty cycle of 50% in really hot weather.
The key to the cheap solution is the power you don’t need never has to be recharged. You need to really compute what you really need or else bite the bullet and buy far more battery capacity than you have now. The bigger alternator aside I doubt it will bridge the gap you have in mind.
I just want to know how long, in minutes, it takes a 900 Watt load to drain a 100 Amp Battery to 50%
Also, will two batteries double the drain time?
Seems like a simple question.
I know it’s a simple question, and simple are the replies above…just do the maths and put in your 900 Watt and 100 Amp Battery.
Here another example with a phone charger and a car battery:
First you have to know how much power your charger draws under load. I looked at my Motorola charger and found it pushes 5v at 550mA to my phone or a total of 2.75 watts. Since no charger is 100% efficient, I’ll more than double it to 6 watts input power (~50% efficient).
After looking at specs for EXIDE batteries it looks like most of their car batteries have 120 minute reserve capacity.
“RC (Reserve Capacity) – The number of minutes that the battery can deliver 25 amps while keeping its voltage above 10.5 volts”
The calculations get hard here, but to really simplify it 10.5v @ 25A equals 265 watts for 120 min. If you reduce that 265 watts to 6 watts it should provide about 5,280 minutes (88 hours) of charging phones. That’s if you had enough dead phones to keep the charger busy for 88 straight hours.
If you aren’t charging your phone but wondering how long it will take to kill your battery with a charger that is not under load you could easily double that time to over 7 days as the charger will still draw a small amount of power even when it’s sitting idle.
Some cars also have “Switched” 12v outlets, meaning that the outlet only gets power when the car is on. In that case it makes no difference because the charger gets no power when the car is not on. (Example, my 2004 Saturn Ion powers the front 12v outlet all the time and the back-seat 12v outlet is switched on only when the car is running.)
I wouldn’t unplug my charger unless I was going to be letting my car sit for over a week. There’s really no practical reason to unplug your charger in any other case.
I’m only the batteries, which will then power household electronics/appliances, such as a computer, T.V., lights and such.
There will be no need to unplug anything, since there will be a charge controller between the panels and the batteries, then a power inverter between the batteries and the AC loads.
I’ll be using 12 Volt 100 AmpHour AGM batteries designed for solar electric power systems, the batteries will get their charge from an array of panels.
From the calculations I’ve made, it seems that one 12 volt 100 AmpHour AGM battery will power a 900 Watt load for approx. 45 minutes.
Divide that by 2 to get a 50% drain, and it’s 22.5 minutes.
So to carry a 900 Watt load for 6 hours each night would require about 16 batteries, and 8 panels 100 Watts each to charge the batteries during the day.
Seems like a lot of hardware to get 6 hours run time per night, but at least I don’t have to import sunlight from anywhere, or tear down a mountain to get it, and it doesn’t pollute the air.
Nice Ken,
I’m sorry if i’ve haven’t told it yet but sometimes is better to learn fishing then…
I have a Odyseey Drycell PC1200 44 amp hrs that I use as an aux. in my van. I just got a VW solar panel, I believe comes with a diod, that runs through the cig. lighter. I’m planning on using it as a trickle charger
Solar panel max outputs are
Power= 3.2W
Volts= 18.8V
Current = 170 mA
my concern is the high voltage, which I hit in direct sunlight. Do you see this a s a problem? What else do I need so I don’t overcharge the battery?
Omar,
I suggest You use a solar charge controller:
http://www.12voltsolarpanels.net/guide-buy-brunton-solar-controller-12volt-battery-charge-monitor
hey,
im want to run a water pump off a 12 volt battery which will be charged by a solar pannel can you suggest what the best kind of solar pannel would be and water pump for my project
Sam have a look here:
http://www.solarwaterfountains.org/solar-fountain-pumps-101
Hi, Can Ileave my solar charger connected to the car/boat battery
while the motor is running?
thank for that link
but its not quite what im looking for i need to pump water from a bore to a water tank and want to run it on battery power which i want to charge by solar pannel. got any ideas?
@Sam – What’s the power of the pump?
@Greg – I think You could leave it connected but ithink it won’t generated any energy if you’re moving.
I have a solar panel that puts out 18v to a regulator that is protected from short circuits and reverse polarity,the reg puts out 13to15v when I connect to the batteries it stops working, when I disconnect from the batteries the solar panel output is the same but the regulator output is down to less than 1volt. When I run the motor the batteries will charge.I tried another regulator with the same result,Its as though the regulator is burning out when I connect to the batteries,which are now flat as a tack.
Any clues/help would be much appreciated
the power of the pump is 600 watts/ 0.8 hp
@Ben – Here a piece of advice I’ve foudn here: http://www.geocities.com/fwarner_au/mc_things/Reg_test.htm
Step 1: Identify the regulator connections.
Step 2: Connections.
Step 3: Testing.
Switch on the power supply and increase the voltage to say 10 volts, the indicator on the load should show an output ie LED lit (or voltmeter indicating).
If no indication switch off the supply and recheck. Check the indicator load by disconnecting the regulator totally, then connect the load indicator directly across the supply (no connection to the regulator), turn on the supply and confirm the indication of ‘output’.
If no indication and the load indicator is working, your regulator is faulty. Congratulations. See the complications section if you want to hit the thing.
If you do have output then increase the supply voltage until the output stops (drops to zero, or near zero). Slightly reduce the voltage so the output just comes back. This should occur when the supply voltage is between 13 and 14 volts. A lower or higher voltage means the regulator is faulty.
continues…
@Sam – You can use this formula:
To calculate the wattage of the solar charger you’ll need to know the Amp/hours (Ampere per Hours) that your battery store.
To calculate the average charge time and then the solar panale wattage:
Take Amp/hour rating of the battery and Divide by the charger rating (in amperes) (*) and then add about 10% for the extra time to top off the battery,
(*) “Watt = Ampere x Volts” “Ampere= Watt/Volts” “Volt= Watt/Ampere”
I.e. Assuming You have a typical full size auto battery, it is about 50 amp hours. (In Your case You need to put Your battery details)
To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger (it’s the medium size of a panel, You can use onemore powerful and then modify the formula below) You’ll need:
1. Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
2. Calculate the division: 50 amp hours / 1,25 ampers = 40 Hours of direct sunlight
3. Add 10%: 4 hours
That’s it calculate the time your battery should operate with Your pump and then choose the panel wattage and battery size you need.
Enrico
thanks for that,
so if i use a 12 volt 79 amp hour battery at full charge what would my run time be on the pump which is 600 watts and wiht 4 amps current, for the batter to empty
Here a method al blog readers could apply easily:
The following method assumes that you know how many amps you need from the battery. If you know the watts go to Step A below.
Step 1. Back of the envelope
If the current drawn is x amps, the time is T hours then the capacity C in amp-hours is
C = xT
For example, if your pump is drawing 120 mA and you want it to run for 24 hours
C = 0.12 Amps * 24 hours = 2.88 amp hours
Step 2. Cycle life considerations
It isn’t good to run a battery all the way down to zero during each charge cycle. For example, if you want to use a lead acid battery for many cycles you shouldn’t run it past 80% of its charge, leaving 20% left in the battery. This not only extends the number of cycles you get, but lets the battery degrade by 20% before you start getting less run time than the design calls for
C’ = C/0.8
For the example above
C’ = 2.88 AH / 0.8 = 3.6 AH
Step 3: Rate of discharge considerations
Some battery chemistries give much fewer amp hours if you discharge them fast. This is a big effect in alkaline, carbon zinc, zinc-air and lead acid batteries. It is a small effect in NiCad, Lithium Ion, Lithium Polymer, and NiMH batteries.
For lead acid batteries the rated capacity is typically given for a 20 hour discharge rate. If you are discharging at a slow rate you will get the rated number of amp-hours out of them. However, at high discharge rates the capacity falls steeply. A rule of thumb is that for a 1 hour discharge rate (i.e. drawing 10 amps from a 10 amp hour battery, or 1C) you will only get half of the rated capacity (or 5 amp-hours from a 10 amp-hour battery). Charts that detail this effect for different discharge rate can be used for greater accuracy. For example the data sheets listed in http://www.powerstream.com/BB.htm
For example, if your portable guitar amplifier is drawing a steady 20 amps and you want it to last 1 hour you would start out with Step 1:
C=20 amps * 1 hour = 20 AH
Then proceed to Step 2
C’ = 20 AH / 0.8 = 25 AH
Then take the high rate into account
C’‘=25 /.5 = 50 AH
Thus you would need a 50 amp hour sealed lead acid battery to run the amplifier for 1 hour at 20 amps average draw.
Step 4. What if you don’t have a constant load? The obvious thing to do is the thing to do. Figure out an average power drawn. Consider a repetitive cycle where each cycle is 1 hour. It consists of 20 amps for 1 second followed by 0.1 amps for the rest of the hour. The average current would be calculated as follows.
20*1/3600 + 0.1(3559)/3600 = 0.1044 amps average current.
(3600 is the number of seconds in an hour).
In other words, figure out how many amps is drawn on average and use steps 1 and 2. Step 3 is very difficult to predict in the case where you have small periods of high current. The news is good, a steady draw of 1C will lower the capacity much more than short 1C pulses followed by a rest period. So if the average current drawn is about a 20 hour rate, then you will get closer to the capacity predicted by a 20 hour rate, even though you are drawing it in high current pulses. Actual test data is hard to come by without doing the test yourself.
I have installed a 15 Watt solar pannel with a solar charge controller on my RV, it has a 12 volt deep cell battery, Do I need to disconect it when I am towing my RV? can I leave it hooked up for several weeks at a time while my RV is in storage, or should I disconect it when I store it? I am hoping to keep the battery charged when it sits in storage and also charge the battery when I am camping without shore power.
Thanks for your help, Bob
I’m looking to construct a PV Solar Panel, which “boasts” an out-put of 15 volts (30 .5o volt cells wired in series). If I construct TWO, and connect them, would that yield 60 volts? ALSO, the electric company mandates an A/C max capacity of not more than 10 kilowatts. How many PV Solar Panels would I need to construct to even come close to that figure? Finally, the device also “boasts” the capability of “plugging” it straight into a wall-socket. Yet, here on the site, I am reading about solar charge controllers and solar current converters. Who’s right?
{ 1 trackback }