250W Solar Panel 24v to 12v batteries

[skasambo]

Thank you for advice...Quick question...how can i know if my panel is 60 cell or 72cell based on measuring Watts produced by each solar at the end of wires before going to solar charge controller???

[LETitROLL]

Thank you for advice...Quick question...how can i know if my panel is 60 cell or 72cell based on measuring Watts produced by each solar at the end of wires before going to solar charge controller???

You need to know the Voc of your panel, Check the sticker on the back, or look up the published ratings for your panel if you know the brand and model, most 72 cell panels have a "Voc" of 43v to 45v, a 60 cell panel (most popular for grid tie) are more in the 38v to 39v range for Voc.

[littleharbor]

Parallel wiring of two 12 volt batteries, as mentioned isn't ideal but.... if you do be sure to connect both CC and load positive leads to the + of one of the batteries and the CC and load negative to the diagonal opposite negative corner of the other battery. This will force the charge and load to go through both batteries.

[skasambo]

If i understand,now i can summarize as follows....i need to rewire my batteries in series,my panel because has 39w at measuring on output it is 60cell that is 20v. I need mppt solar charge controller and not pmw....how to tap my invertor and 12v load from that 24v series batteries so far not sure.Please help me to understand

[jflorey2]

With MTTP,how much Watt will get

Depends. Between about 150 and 200 watts in direct sun depending on a great many things.

[LETitROLL]

If i understand,now i can summarize as follows....i need to rewire my batteries in series,my panel because has 39w at measuring on output it is 60cell that is 20v. I need mppt solar charge controller and not pmw....how to tap my invertor and 12v load from that 24v series batteries so far not sure.Please help me to understand

While wiring your batteries in series (24v) is best, if your panel is a 60 cell (which it seems to be) it may not charge the battery well all the time, depending on state of charge, weather, etc. , your need for a Mppt controller is greater if you stay with 12v battery bank, that will harvest all of the available power from your bigger panel and convert it to use with the 12v battery(s), if you try the 24v battery bank, your PWM controller would not be so bad, but then you will need a DC-DC step down converter to go from the 24v down to your 12v devices.

[Amy@altE]

Because you have a 20V panel, and 12V loads, I would wire the batteries in parallel to keep it 12V and get an MPPT charge controller (for the record, the squares that make up the solar panel are the cells. You can just look at it and count the squares on the front, if there are 60 squares, that is 60 cell, 20V.)

[skasambo]

Team
Can 24v dc convetor to 12v dc can work even the batter voltage is below 24v?

[skasambo]

What are the requirements of 24v dc to 12v dc convertor with 15A to work better with a solar charge controller of 50A?

[skasambo]

While wiring your batteries in series (24v) is best, if your panel is a 60 cell (which it seems to be) it may not charge the battery well all the time, depending on state of charge, weather, etc. , your need for a Mppt controller is greater if you stay with 12v battery bank, that will harvest all of the available power from your bigger panel and convert it to use with the 12v battery(s), if you try the 24v battery bank, your PWM controller would not be so bad, but then you will need a DC-DC step down converter to go from the 24v down to your 12v devices.

You say i can make the parallel with 12v,but my panel is 24v...how that can be possible...

[Wy_White_Wolf]

With MTTP,how much Watt will get

about 240W (250 / efficiency rating of charge controller)

WWW

[Logan005]

with your current set up, you can only wire the batteries parallel, since a 24 volt panel will not likely charge a 24 volt battery, but with an MPPT your 24 volt panel will charge your 12 volt battery. If you obtain another 24 volt panel, you can wire them in series as well as your batteries for 24 volts. once you have a 24 volt bank, you will need to replace your inverter and purchase a DC to DC converter for your 12 volt loads. 24 volts is much better than 12 volts for many reasons. a 12 volt inverter w/o huge terminals is safe for about 700 watt's, but a 24 volt inverter is good for 1400 watts, Even better when you advance to 48 volts. 12 volts is for cars, Toys and RV's, not so good for off grid.