Just New - Charger Calculation - Need Help

[curious_me]

Hi everyone,

I'm new to Solar and have just registered on this site hoping someone could guide me to the right path.

First of all I'm planning to build this project as my permanent power source.

I'm looking at 6pcs x 2v 500AH Deep cycle battery in series to have a total of 12v 3000AH Battery Bank.
My questions are:

1. What is the rating (in Amp) the Charge Controller that I would need to charge this battery bank for 6 hours ?
I can only see Charge controller on the web from 10Amp to 40Amp.

2. How many watts of paralleled Solar Panel in (100watts each) would I need to accomplish the charging mentioned in # 1 ?
Would the Charge Controller accommodate these wattage ?

Thanks in advance.

[Mike90250]

The wattage needed to charge the massive 12v battery array is likely going to force you to 2, 60A charge controllers. $$$$
It would be better to wire this array in series and get a 48V battery that just 1 controller $$ can charge.

12V @ 3,000ah = 36000wh **
36000wh @ 48V = 750Ah which is still a pretty large battery.

You want to deliver at least 10% of your rated Ah, as charging current to the batteries. 15% is better for the tall batteries to keep the electrolyte stirred up and de-stratified.

So, for that 12v bank, that would want 300A, which would be 5 charge controllers.
At 48V, it would be 75A, needing just 2 controllers.

The size of the array will vary according to your daytime loads that will consume power before it gets to charging the batteries, so maybe figure the 15% of battery AH capacity.

Battery systems are only about 50% efficient, end to end, so if you consume 3Kw daily, you need to harvest 6Kw.

Daytime length is also a factor, the further north you are, the less sun hours, so you need to compensate with a larger array, or plan on running a generator 4x a week to keep the batteries up above 50%.

** Your battery calc is WRONG. 6, 2V 500ah cells in series gives you 12V 500A (not 3,000A) or 6,000wh.
It would only need 50 - 75 A for charging, so a single 60A MPPT controller could just barely do it.

I'd suggest the Midnight Classic 150 or second, the Morningstar MPPT 60

[curious_me]

Hi Mike,

Thank you for pointing out my computation mistake on the total AH for the 6 x2V 500AH. I was always thinking of parallel connection but then shifted to series due to high amperage capacity of the 2V Deep Cycle batteries. I guess I was overwhelmed there. This also led me to an incorrect calculation on the price vs. the 12v 200AH

Looks like I have to go back to the 12v 200Ah capacity each.

I'm new to solar, so I'm trying to grasp the idea specially in the computation.
Here are the readily available resources that can be purchased somewhere in our area which I'm still trying to decide of which one to choose. I do hope this forum would be able to let me decide which one is better. Though you also mentioned the 48v is better, however, resources available in our area is only 12v and it would be hard to find others:
1. 2v 500AH Deep cycle battery - scratching this from the list as it will cost too much.
2. 12v 200AH Deep cycle battery
3. 10-40A Solar Charge Controller - need to identify what's the right choice here.
4. 100Watts Solar Panels - need to know how many I need to be able to charge a specific amount of battery
5. 12vdc to 220vAC 1000w Inverter

Considering the above I could start with the following as an example in consideration of the budget:

2 x 12v 200AH = parallel (12v 400AH)

Given this, I would like to know the capacity of the Charge Controller that would be needed to charge the 12v 400AH in 6hrs of continuous sunlight. Also in consideration for possible future expansion of either half or same amount as the battery bank mentioned.

How many Solar Panel of 100watts each in parallel would be needed to charge this battery in 6hrs.
Say consumption would be:
fridge 150 watts x 12 hrs =1800wh
lights 10 pcs x 10 watts x 12hrs =1200wh (never mind the light this could be another device)
Total of 3kw per day

Would you mind giving me the formula to calculate this with only the following value above. So, I can apply the math with other value to match my options.

Thanks.

[Mike90250]

so, I've moved this post to the proper forum - Off Grid

We have some stickie posts, that cover your questions, I've selected this order for you to read them. Open them all in new tabs (generally, you right click on the link, and chose Open In New Tab)
You may have to read them each a couple times, but first I'll warn you , you determine the LOADS, then build the system to support the loads, not: here's some batteries, how much charging do I need?

http://www.solarpaneltalk.com/showthread.php?7592-So-You-Want-To-Go-Off-Grid-Battery

http://www.solarpaneltalk.com/showthread.php?2144-How-Many-Batteries-amp-Why-Tutorial

http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design

http://www.solarpaneltalk.com/showthread.php?10450-Inverter-Size-vs-Battery-Size-Tutorial

http://www.solarpaneltalk.com/showthread.php?7634-Watts-vs-Volt-Amps-huh

http://www.solarpaneltalk.com/showthread.php?14485-Sizing-Off-Grid-Systems-And-Using-Gen-Support

http://www.solarpaneltalk.com/showthread.php?13845-Charge-Controllers-PWM-or-MPPT

Then take 2 aspirin.

[Wy_White_Wolf]

Hi everyone,

I'm new to Solar and have just registered on this site hoping someone could guide me to the right path.

First of all I'm planning to build this project as my permanent power source.

I'm looking at 6pcs x 2v 500AH Deep cycle battery in series to have a total of 12v 3000AH Battery Bank.
My questions are:

1. What is the rating (in Amp) the Charge Controller that I would need to charge this battery bank for 6 hours ?
I can only see Charge controller on the web from 10Amp to 40Amp.

2. How many watts of paralleled Solar Panel in (100watts each) would I need to accomplish the charging mentioned in # 1 ?
Would the Charge Controller accommodate these wattage ?

Thanks in advance.

Wrong. Those 6 batteries in series would be 500AH @ 12V.

When wired in series you add the voltages but the AH stays the same. When you wire in parrallel the voltage stays the same and the AH are added.

Ideally a 500AH battery should be charged between C/8 and C/12 with C/10 being about ideal.

C/8 = 62.5A
C/10 = 50A
C/12 = 41.7A

So a 60A MPPT controller would be about right.

To achive the C/10 rate you multiply the amperage by the charge voltage.

50A * 14.4V = 720W of panels. You might want to oversize this a little if you have less then ideal mounting conditions.

WWW

WWW

[Wy_White_Wolf]

...How many Solar Panel of 100watts each in parallel would be needed to charge this battery in 6hrs.
Say consumption would be:
fridge 150 watts x 12 hrs =1800wh
lights 10 pcs x 10 watts x 12hrs =1200wh (never mind the light this could be another device)
Total of 3kw per day
...

What's your location?

Most likely you don't have 6 hours on insolation available. More likely only 2.5 to 3 in the winter if you are in the US. Your battery would also be hard pressed to supply that much power. You'd be discharging it by 50% daily which leaves you with no atonomy. Batteries should only be discharged by 20% daily.

WWW

[SunEagle]

Hi Mike,

Thank you for pointing out my computation mistake on the total AH for the 6 x2V 500AH. I was always thinking of parallel connection but then shifted to series due to high amperage capacity of the 2V Deep Cycle batteries. I guess I was overwhelmed there. This also led me to an incorrect calculation on the price vs. the 12v 200AH

Looks like I have to go back to the 12v 200Ah capacity each.

I'm new to solar, so I'm trying to grasp the idea specially in the computation.
Here are the readily available resources that can be purchased somewhere in our area which I'm still trying to decide of which one to choose. I do hope this forum would be able to let me decide which one is better. Though you also mentioned the 48v is better, however, resources available in our area is only 12v and it would be hard to find others:
1. 2v 500AH Deep cycle battery - scratching this from the list as it will cost too much.
2. 12v 200AH Deep cycle battery
3. 10-40A Solar Charge Controller - need to identify what's the right choice here.
4. 100Watts Solar Panels - need to know how many I need to be able to charge a specific amount of battery
5. 12vdc to 220vAC 1000w Inverter

Considering the above I could start with the following as an example in consideration of the budget:

2 x 12v 200AH = parallel (12v 400AH)

Given this, I would like to know the capacity of the Charge Controller that would be needed to charge the 12v 400AH in 6hrs of continuous sunlight. Also in consideration for possible future expansion of either half or same amount as the battery bank mentioned.

How many Solar Panel of 100watts each in parallel would be needed to charge this battery in 6hrs.
Say consumption would be:
fridge 150 watts x 12 hrs =1800wh
lights 10 pcs x 10 watts x 12hrs =1200wh (never mind the light this could be another device)
Total of 3kw per day

Would you mind giving me the formula to calculate this with only the following value above. So, I can apply the math with other value to match my options.

Thanks.

With a 3kWh daily load you can use the following battery, panel wattage, charge controller and inverter information as a guide line. There are a number of ways to get where you want to go but what I list should do the trick.

3kWh/day * 5 days = 15kWh battery.

Using 24volt that comes to about 625Ah battery system which can be; 4 x 6v 625Ah, 6 x 4v 625Ah or 12 x 2v 625Ah.

Depending on where you live let say you get 2.5 hr of "good" sunshine a day in the Winter. So you will need about 2000 watts of panels.

With 2000 watts of panels to charge a 24volt system you need an 80amp MPPT type charger.

The inverter can be around 1000 watts but due to the fridge I would go with a Pure Sine Wave one.

[curious_me]

Just got back from work.

Thanks Mike, for the links that's very informative and yes had to take panadol instead of aspirin.

Thanks WWW, for the calculations it give me an idea, the battery that I could get is 12v 200AH-10hr as it's the easiest one to get in my place and comparing it to the 2v500AH x 6pcs will cost a fortune. I'm located in the philippines near the coast so I can say 6hrs of nice bright sunlight. And also thinking about the comparison between mono and poly panels, which one would be more efficient when it comes to cloudy skies. We only have 2 types of weather in the country summer and rainy. So i'm trying to consider the efficiency of the panels as well.

Thanks SuneEagle, for the idea regarding the capacity of the controller and the type of inverter.


With all your answers combined and from a few research that I made. please correct me with the formula below if it's incorrect.

Scenario : for now I'm not trying to consider the loads/consumption as I can adjust that later once I get the correct computation.
Given values : 12v 200AH-10hr deep cycle battery
Charging time: 6 hours
Required : Charge controller Amp capacity
Required : Total Wattage that Solar Panels needed


Amps required for Charge Controller = (Battery Capacity / Charging time a day)
Total Wattage for Solar Panel required to charge the given battery in the given hours = Amps required for charge Controller X 12v battery capacity

200AH/6H = 33.33333 Amps
33.33A x 12V = 400 Watts

Therefore from the computation above:

The Charge Controller Capacity would be at least 40amps
The Solar Panel should be at least 400 Watts (or 400+ watts)

Also since we are computing this in a full 200AH capacity without loads, meaning if this has a load just about approximately enough, it would only be at least 50% of this computation considering that we are not going to use the full 200AH instantly or at least we can only use half the capacity. Maybe this is where I lost it again.

But yes please do advise and enlighten me more.

Thank you.

[Mike90250]

Golf cart batteries ( 6v, 200ah) are often a great starter kit, 2 of them are easier to haul around than a giant 12V 200ah battery.

Got any golf courses there to get a battery from ?

[curious_me]

Mike, it's difficult to obtain a golf cart batteries here. there's only 1 or 2 golf court in my place and it's quite far. So sourcing battery of this type is not very viable.
The area where I'm from is quite remote and what they sell here are just regular car battery with the exception of the one that I mentioned. It is readily available on that store an in case of a bad unit it can be replaced right away. While sourcing from a very far place would cost a lot and in case of bad unit, then its an added problem.

Regarding my calculation, am I getting there? if I am, then I just have to improve it more and include loads and power loss calculations so losses can be dealt with prior to pursuing the project.

Thanks.

[Mike90250]

to really do the calc, we need the loads, split between night loads and daytime. Daytime loads subtract power from charging the battery, so you need even more solar panels !

[russ]

Mike, it's difficult to obtain a golf cart batteries here.

Where is "here"?

[paulcheung]

. I'm located in the philippines near the coast so I can say 6hrs of nice bright sunlight. And also thinking about the comparison between mono and poly panels, which one would be more efficient when it comes to cloudy skies. We only have 2 types of weather in the country summer and rainy. So i'm trying to consider the efficiency of the panels as well.

Thank you.

He said near Philippines

[inetdog]

He said near Philippines

Some islands are too small for golf courses. <sigh>

[curious_me]

to really do the calc, we need the loads, split between night loads and daytime. Daytime loads subtract power from charging the battery, so you need even more solar panels !

Mike,

Here are the proposed loads with ASPIRIN taken into account the super high investment.

Is this reasonable and would this pay off.

Loads.JPG