Newbie in Solar setup, need help for computation

[raymondalmeda]

Hi,

Like what the title says, I'm a newbie with solar setups. I've done some research before I bought my stuff but then again it's all theoretical. My problem is that I need to figure out how much power can my system generate and amp draw in different time spans e.g. 24, 20, 12, 8, 4, and 2 hours.

I also need help on what wire sizes I should use and the angle that I should put it up.

Here's the stuff that I bought:

3x 100watt solar panels 12volts @5.71a
2 x 100Ah (RC/20) AGM Deep Cycle Batteries (I will add 3 more when next month)
Wellsee 60A solar controller (http://www.wellsee.cc/ProContent_Editor.aspx?action=94)
1kva pure sine wave inverter (Power Factor @87%)

I'm a little constrained with the budget that's why this is what I have for now.

I hope you guys can help me.

Thanks!

[russ]

Hi Raymond - Welcome to our forum - Solar Panel Talk!

Lets see what comments you get.

Russ

[raymondalmeda]

Hi Raymond - Welcome to our forum - Solar Panel Talk!

Lets see what comments you get.

Russ

Thanks Russ! Looking forward on getting some help with tht community! It was great finding this site!

[Sunking]

Depends, where are you located? This time a year 600 watt hours or less. About enough to run a laptop and a small light for a day.

[Mike90250]

Don't buy any more batteries, you don't have enough solar to keep them charged.

[raymondalmeda]

Don't buy any more batteries, you don't have enough solar to keep them charged.

Hi Mike!

Thanks for the advice, I have some questions though. In my current setup, will my panels suffice to fully chare my batteries? By any chance you have a ball park figure on how log will it take to fully charge from a 50% discharged state?

If ever (which I'm really planning) I buy 3 more batteries of the same specifications. How much more panels would I need to cope up with the increase number of batteries?

Thanks!

[Mike90250]

Sorry about mangling your post.

as a rule of thumb, you need 10% of your battery capacity, to properly recharge the battery. So if you had a 12V 100AH battery, your PV needs to produce 10 amps @15V, or 150W of panel.

[Sunking]

Raymond it is all about location and type of charge controller.

You have 2 12 volt batteries rated at a total of 200 AH which is 2400 watt hours reserve capacity. At the recommended 20% discharge rate per day your batteries can supply 2400 wh / 5 = 480 watt hours per day, and never more than 1200 wh to 50% DOD.

But that is only half the problem, you panels have to be able to replace what is used each day plus efficiency losses. To determine that depends on your location and panel wattage. As of now you have 300 watts of solar panel wattage, which depending on your location should be able to keep up with the batteries if you do not over discharge them.

I do not know where you are but assuming it is not Seattle WS and you get at least 3 Sun Hours in December using a MPPT charge controller your panels can generate 300 watts x 3 hour x .66 = 600 watt hours.

Right now your panel wattage to battery capacity appears to be matched up, depending on your LOCATION. The limitation is you can only use up to 600 watt hours per day. Go over that and your batteries will likely fail from running in deficit.

[raymondalmeda]

Sorry about mangling your post.

as a rule of thumb, you need 10% of your battery capacity, to properly recharge the battery. So if you had a 12V 100AH battery, your PV needs to produce 10 amps @15V, or 150W of panel.

So, If I got it right, the 3 12volts 100Watt Panels I have rated @5.71amps each should just be fine with the 2 12volt 100Ah batteries I have. So if ever I would need to expand my battery bank with 2 more batteries, I would need 3 more panels right? If so, how long would it take to fully charge them?

Thanks Mike!

[raymondalmeda]

Raymond it is all about location and type of charge controller.

You have 2 12 volt batteries rated at a total of 200 AH which is 2400 watt hours reserve capacity. At the recommended 20% discharge rate per day your batteries can supply 2400 wh / 5 = 480 watt hours per day, and never more than 1200 wh to 50% DOD.

But that is only half the problem, you panels have to be able to replace what is used each day plus efficiency losses. To determine that depends on your location and panel wattage. As of now you have 300 watts of solar panel wattage, which depending on your location should be able to keep up with the batteries if you do not over discharge them.

I do not know where you are but assuming it is not Seattle WS and you get at least 3 Sun Hours in December using a MPPT charge controller your panels can generate 300 watts x 3 hour x .66 = 600 watt hours.

Right now your panel wattage to battery capacity appears to be matched up, depending on your LOCATION. The limitation is you can only use up to 600 watt hours per day. Go over that and your batteries will likely fail from running in deficit.

Thanks for that Sunking! I'm currently in the Philippines at aproximately 10 - 15 degrees above the equator. Would that make the computations a little more closer to accurate?

[Sunking]

I would need 3 more panels right? If so, how long would it take to fully charge them?

No not necessarily. Charge them from depth of discharge and what time of year?

You are going about this the wrong way. Off-Grid battery systems are designed based on how many watt hours you use in a day, location, and number of days in battery reserve.

In the Philippines December is your shortest Sun Hour Days of 5.3 hours. So assuming you use a MPPT controller you can generate 300 watts x 5.3 hours x .66 = 1049 watt hours of usable energy. So let's just say 1 Kwh. Pretty good with just a 300 watt solar panel

Problem is your batteries are not sized correctly to supply you with 1 Kwh of power per day. At 12 volts you would need 5000 / 12 volts = 416 AH of battery. Right now you only have 200 AH. So you can double up on batteries with your current solar panel wattage.

[raymondalmeda]

No not necessarily. Charge them from depth of discharge and what time of year?

You are going about this the wrong way. Off-Grid battery systems are designed based on how many watt hours you use in a day, location, and number of days in battery reserve.

In the Philippines December is your shortest Sun Hour Days of 5.3 hours. So assuming you use a MPPT controller you can generate 300 watts x 5.3 hours x .66 = 1049 watt hours of usable energy. So let's just say 1 Kwh. Pretty good with just a 300 watt solar panel

Problem is your batteries are not sized correctly to supply you with 1 Kwh of power per day. At 12 volts you would need 5000 / 12 volts = 416 AH of battery. Right now you only have 200 AH. So you can double up on batteries with your current solar panel wattage.

I really appreciate your help! I am planning on buying 3 more of the batteries of what I have and connect them in parallel. I'm just a little concerned about what Mike said in the previous post of not adding more batteries since my panels can't charge them anymore. Can you help me understand that statement please?

Thanks!

[Mike90250]

If so, how long would it take to fully charge them?

Depends on how deeply you discharge them. I've got no way of knowing this answer.

[raymondalmeda]

Depends on how deeply you discharge them. I've got no way of knowing this answer.

Hi Mike!

I'm planing to just use them upto 60% then I'll configure the controller to auto-cut off the load when it reaches that point.

Thanks!

[Sunking]

Hi Mike!

I'm planing to just use them upto 60% then I'll configure the controller to auto-cut off

You are planning taking them down to far.