what charge controller do I need for a 250watt panel

[Bucho]

hahahahahaha!! nice one. Next question: is it possible to charge a battery with two sources. solar panels and grid? does this have an effect (good or bad) on the batteries like making the batteries charge faster etc.

Yes, you can charge from multiple sources as long as you stay below 1/8 of your capacity (assuming you have FLA's).

[Bucho]

well my total watt is 200 at 24 volts. 200 w x 24 v = 4,800 wh. Does this sound right??

I'd believe 4,800Wh That would be 200ah x 24v.

If your batteries are deep cycle FLA's you should charge them between 1/8 to 1/12 of their capacity so once you get your MPPT you should be in good shape.

[fopoku2k2]

Yeah my bad. My poin tis I wanted you to figure it out. and you did.

hahahahahaha!! nice one. Next question: is it possible to charge a battery with two sources. solar panels and grid? does this have an effect (good or bad) on the batteries like making the batteries charge faster etc.

[fopoku2k2]

That doesn't sound right, would you double check that.

well my total watt is 200 at 24 volts. 200 w x 24 v = 4,800 wh. Does this sound right??

[Bucho]

My current total battery amp hours is 4,800

That doesn't sound right, would you double check that.

[Sunking]

I think you meant 50 amps x 24 volts = 1,200 watts. Since my batteries are hooked up in series to generate 24 volts

Yeah my bad. My poin tis I wanted you to figure it out. and you did.

[fopoku2k2]

Well there you go. You could have also got real close doing the math.

50 amps x 12 volts = 600 watts.

I think you meant 50 amps x 24 volts = 1,200 watts. Since my batteries are hooked up in series to generate 24 volts

[Sunking]

In the MPPT's specifications sheet it says 12v is 700w and 24v is 1,400w

Well there you go. You could have also got real close doing the math.

50 amps x 12 volts = 600 watts.

[fopoku2k2]

I am not going to tell you. I will teach you how to fish so you can feed yourself with an answer.

MPPT Output Current = Panel Wattage / Battery Voltage

Do some simple 5th grade math and the Formula can be rewritten as: Panel Wattage = Battery Voltage x Charge Current

So you tell me what the maximum panel wattage for 12, 24, and 48 volt battery is? Either that or look in the owners manual.

In the MPPT's specifications sheet it says 12v is 700w and 24v is 1,400w

[Sunking]

I went ahead and ordered a 50 A, 150 VDC MPPT charge controller. How many more 250 watt, 30.3 Vmp, 8.27 Imp, 37.7 Voc, 8.69 Isc solar panels can I connect to this charge controller in addition to my current 2 x 250 watts

I am not going to tell you. I will teach you how to fish so you can feed yourself with an answer.

MPPT Output Current = Panel Wattage / Battery Voltage

Do some simple 5th grade math and the Formula can be rewritten as: Panel Wattage = Battery Voltage x Charge Current

So you tell me what the maximum panel wattage for 12, 24, and 48 volt battery is? Either that or look in the owners manual.

[fopoku2k2]

That is in series. With a PWM controller Input Current = Output Current With a MPPPT controller Output Current = Panel Wattage / Nominal Battery Voltage

It takes 18 volts per 12 volt of battery to charge them efficiently. That is why battery panels have 36 cells, each cell is .5 volts or a Vmp of 18 volts. Grid tied panels like your use more cells which is a good thing because higher voltage is more efficient and a lot cheaper. But you must use MPPT controller when using Grid Tied panels.

When you use a PWM controller like you have, you have to use expensive 36 cell battery panels. Example if you used your panels in parallel on a 12 volt battery system your charge power is reduced from 500 watts to 192 watts (16 amps x 12 volts) Just call it 200 watts or 100 watts from each 250 watt panel. Use a MPPT and you get roughly 475 watts when taking conversion losses into consideration and 475 watts @ 12 volts = 40 amps vs only 16 with PWM.

So now that you know go shopping for a 20 amp minimum MPPT controller. Be careful cheap ones are really PWM, check Voc input voltages, you want one with at 100 Voc input. A good one is going to cost you more than $200.

I went ahead and ordered a 50 A, 150 VDC MPPT charge controller. How many more 250 watt, 30.3 Vmp, 8.27 Imp, 37.7 Voc, 8.69 Isc solar panels can I connect to this charge controller in addition to my current 2 x 250 watts

[solarix]

OP is in the problem gap of too big to make a PWM controller work well, and too small to make a MPPT controller cost effective. If you want to do about a 500w array, you either spend a lot of money on almost out of production, expensive 12V type panels in order to make the PWM controller not so wasteful, or you spend lots on a expensive MPPT controller to make a couple of good value 24V type panels work well.
Answer is: you are going to want to add more power (more power, more power) later, so bite the bullet and get the good, efficient MPPT controller now and you'll be happy in the long run.

[Sunking]

Wow. 192 watts out of 500 watts. OMG!!!

I'm guessing even in series since my current would be small I would be using smaller batteries to bring down my arising cost.

That is in series. With a PWM controller Input Current = Output Current With a MPPPT controller Output Current = Panel Wattage / Nominal Battery Voltage

How did you get the 36 volts minimum for a 24 volt battery?

It takes 18 volts per 12 volt of battery to charge them efficiently. That is why battery panels have 36 cells, each cell is .5 volts or a Vmp of 18 volts. Grid tied panels like your use more cells which is a good thing because higher voltage is more efficient and a lot cheaper. But you must use MPPT controller when using Grid Tied panels.

When you use a PWM controller like you have, you have to use expensive 36 cell battery panels. Example if you used your panels in parallel on a 12 volt battery system your charge power is reduced from 500 watts to 192 watts (16 amps x 12 volts) Just call it 200 watts or 100 watts from each 250 watt panel. Use a MPPT and you get roughly 475 watts when taking conversion losses into consideration and 475 watts @ 12 volts = 40 amps vs only 16 with PWM.

So now that you know go shopping for a 20 amp minimum MPPT controller. Be careful cheap ones are really PWM, check Voc input voltages, you want one with at 100 Voc input. A good one is going to cost you more than $200.

[fopoku2k2]

Yeah...I was afraid of that. Those panels are made to feed the power grid, you can't depend on them to completely charge 24v batteries, which would be a slow death sentence for your batteries. You'll have to use your 2 24v panels in series which means that a MPPT controller will be important for you.

How many amp hours is your battery bank?

My current total battery amp hours is 4,800

[Bucho]

My Vmp is 30.3

Yeah...I was afraid of that. Those panels are made to feed the power grid, you can't depend on them to completely charge 24v batteries, which would be a slow death sentence for your batteries. You'll have to use your 2 24v panels in series which means that a MPPT controller will be important for you.

How many amp hours is your battery bank?