matching a 300w 36v solar panel to my 12v battery and 12/24v inverter, please advice

[chacha4423]

Hi, I am new to this technology but have been interested about solar energy since way back 30 years ago in high school, i recently acquired a solar pv system from a friend , actiually separate parts bought separately from different sources, i have a 12/24v 20a solar controller, a 300w 36v panel, a 12/24v 3000w inverter and a 12v 500Ah battery. the problem arised when i found out that the panel was 36v and not 12v as i expected, do i need anything else to match the 36v to the 12v battery and inverter thanks in advance

actual rating of the Panel

Pmax 300w
Voc 42.48v
Isc 9.16A
Vmp 36v
Imp 8.33A
Vmax 1000v

tolerance +-3%

[inetdog]

Hi, I am new to this technology but have been interested about solar energy since way back 30 years ago in high school, i recently acquired a solar pv system from a friend , actiually separate parts bought separately from different sources, i have a 12/24v 20a solar controller, a 300w 36v panel, a 12/24v 3000w inverter and a 12v 500Ah battery. the problem arised when i found out that the panel was 36v and not 12v as i expected, do i need anything else to match the 36v to the 12v battery and inverter thanks in advance

actual rating of the Panel

Pmax 300w
Voc 42.48v
Isc 9.16A
Vmp 36v
Imp 8.33A
Vmax 1000v

tolerance +-3%

Hello chacha and welcome to Solar Panel Talk!

If your charge controller (CC) is the Pulse Width Modulated (PWM) type, then you can go ahead and use it safely but you will get only about a third of the panel wattage in the form of useful charging current.

If you get (or already have) an MPPT type CC, then it will transform the voltage so that you are sending almost all of the panel power to batteries.

Simple rules (approximations):
PWM CC: Current in = current out.
MPPT CC: Power in = power out.

[chacha4423]

Hello chacha and welcome to Solar Panel Talk!

If your charge controller (CC) is the Pulse Width Modulated (PWM) type, then you can go ahead and use it safely but you will get only about a third of the panel wattage in the form of useful charging current.

If you get (or already have) an MPPT type CC, then it will transform the voltage so that you are sending almost all of the panel power to batteries.

Simple rules (approximations):
PWM CC: Current in = current out.
MPPT CC: Power in = power out.

Tnx inetdog, so you are saying that the voltage rating of 36v in the panels are not a problem when i connect it to the PWM CC that i have it will charge the 12v battery at a correct voltage then stop when the battery is fully charge, so approximately 100w will be utilized to charge my 500AH 12v battery, how long does it take to fully charge this battery, tnx for the reply

[Sunking]

If your charge controller (CC) is the Pulse Width Modulated (PWM) type, then you can go ahead and use it safely

Not always as not all controllers can handle that high of a voltage on a 12 volt battery.

With a Grid Tied which you have, you should be using a MPPT Controller. If you had used a MPPT controller would have provided 25 amps of charge current. With your panel and a PWM controller all you are going to get is 8.3 amps or about 99 watts. You just as well throw the panel away and get a 12 volt 100 watt panel.

You really need to get rid of your controller and get a 25 amp or higher MPPT controller.

[chacha4423]

Not always as not all controllers can handle that high of a voltage on a 12 volt battery.

With a Grid Tied which you have, you should be using a MPPT Controller. If you had used a MPPT controller would have provided 25 amps of charge current. With your panel and a PWM controller all you are going to get is 8.3 amps or about 99 watts. You just as well throw the panel away and get a 12 volt 100 watt panel.

You really need to get rid of your controller and get a 25 amp or higher MPPT controller.

Tnx Sunking, i am new to this so the specs i got were not a good match, do have any idea the cost difference between the MPPT and the PWM type of controller because here in my area i can only get hold of the PWM, i'll try to look for a 25A or 30A MPPT controller but for now i'll just make use of what i have so i can start using it.

if in case a get an MPPT cc , can i charge 2 500AH battery in parallel meaning 2 12v "+" to "+" and "-" to "-" tnx

[Sunking]

Tnx Sunking, i am new to this so the specs i got were not a good match, do have any idea the cost difference between the MPPT and the PWM type of controller because here in my area i can only get hold of the PWM, i'll try to look for a 25A or 30A MPPT controller but for now i'll just make use of what i have so i can start using it.

if in case a get an MPPT cc , can i charge 2 500AH battery in parallel meaning 2 12v "+" to "+" and "-" to "-" tnx

At this point you would be better of just using 24 volt battery. You really do not have enough panel wattage to support the batteries.

[chacha4423]

At this point you would be better of just using 24 volt battery. You really do not have enough panel wattage to support the batteries.

for the mean time i will just try to charge the battery while waiting for my MPPT controller, by then i would connect my inverter to the line, Tnx for all the advice and technical knowledge shared

[mapmaker]

if in case a get an MPPT cc , can i charge 2 500AH battery in parallel meaning 2 12v "+" to "+" and "-" to "-" tnx

Actually, you will barely be able to adequately charge one battery with a 300 watt panel. If you want to increase your battery bank, you will need more panels and a MPPT controller that can handle 50 amps.

NOTE: the same controller that can handle a 300 watt panel with a 12 battery will be able to handle 600 watts with a 24 volt battery. If you put your two batteries in series (24 volts) you will have a more efficient, more stable, more capable, and less expensive system than if you put the two batteries in parallel.

Of course, you will need a 24 volt inverter (rather than a 12 volt inverter).

--mapmaker

[chacha4423]

Actually, you will barely be able to adequately charge one battery with a 300 watt panel. If you want to increase your battery bank, you will need more panels and a MPPT controller that can handle 50 amps.

NOTE: the same controller that can handle a 300 watt panel with a 12 battery will be able to handle 600 watts with a 24 volt battery. If you put your two batteries in series (24 volts) you will have a more efficient, more stable, more capable, and less expensive system than if you put the two batteries in parallel.

Of course, you will need a 24 volt inverter (rather than a 12 volt inverter).

--mapmaker

Thanks mapmaker, i have ordered a 50A MPPT SOLAR CONTROLLER and still weighing my options on either 12 or24v system

[Sunking]

Thanks mapmaker, i have ordered a 50A MPPT SOLAR CONTROLLER and still weighing my options on either 12 or 24v system

Well with a 50 amp MPPT controller you will be maxed out at 600 watts input operating 12 volts. At 24 volts you can go up to 1200 watts.

[paulcheung]

You already have the 12/24 volt inverter, so go with 24 volts and you have more rooms to grow later. if you have to use some 12 volts DC, you can get one of those 24 volt to 12 volt converter.

[chacha4423]

Well with a 50 amp MPPT controller you will be maxed out at 600 watts input operating 12 volts. At 24 volts you can go up to 1200 watts.

Sorry for the wrong info, i just found out that the inverter was 12v only