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I am in the mist of setting up a kW off grid system for my garage and have purchase all the equipment except for the battery bank. I purchased 4*250 Watt (24V) panels plus the install kit
Maximum Power 250W
Open Circuit (Voc) No Load 37.6V
Short Circuit (lsc) No Load 8.70A
Maximum Power Voltage (Vmp ) 30.6V
Maximum Power current(lmp) 8.17A
My Solar Controller is
This MPPT is designed to auto detect 12V, 24V or 48V battery systems and select a suitable charge regime.
The maximum absorption voltage is 14.5V, 29V or 58V and the float voltage is 13.5V, 27V
and in my haste, brought a $600 - 12V inverter
|Output Voltage and Frequency||240V AC, 50Hz±5%|
|Output Wave||Pure Sine Wave|
|Socket Type||Australian Standard|
|Battery Low Alarm Protection||10VDC±0.5V or 20.5VDC±1V or 44VDC±1V|
|Battery Low Shutdown Protection||9.5VDC±0.5V or 19.5VDC±1V or 42VDC±1V|
|Overload Protection||Shuts down output - re-power to reset|
|Over Voltage Protection||15-16V|
|Over Temperature Protection||>60°C|
|Output Short Protection||Auto Shut-off|
|In the Box||5000W Inverter, DC Battery cables|
So my question before I blow myself up, can I setup the solar panels and controller as 24 volt and to charge the battery bank of 12 Volts (wanted 2*6v 230Ah Series + 2*6v Ah series) then parallel them to be 12V @ 460Ah. Or do I bite the bullet and buy a 24vdc Inverter? Just don't want to waste the $600 inverter as it now past the return period.
PS I am a greenhorn at all this so any advise with help.
First off.. Welcome aboard.
To answer the basic question.. Yes , no issue using your MPPT controller to charge a 12v battery bank. It will step down the voltage to the needed charging power and will not cook off the extra voltage but will instead use the extra amps to charge the batteries.
My first question is where you are located? The inverter you have listed is a 240v output with Australian specs. So this will not work for you if you are located in the US.
It looks like you are on the path so lets talk a bit more.
Thank Big Moe,
Yes I'm In Australia, electricity prices here are on the rise so, I'd thought of converting the garage Off grid to save some money in the longer term. My idea goal is to virtually take it off the grid, except for my fridge/freezer. Don't know too much about what the start up draw is, all i have is it uses 475 Whr/year and using an Volt meter ran at 1422 W at high (left door open for 15 minutes) and low range of 4W. I've looked at the tech spec for it but there is no details for it. How can this be achieved without frying the motor or is it a bad idea..??
I wanted to connect these batteries via Inverter to a circuit bus bar and have it directed to lights, garage door, exhaust fan for my BBQ, and a few power points for some of my tools/Chargers.
The last goal was to run the 240V into my house and have selected power points, to run the T.v's/PC ect, a range of lights on a separate switch to the Mains power . Here in Australia, I can do all the work for ELV systems but when it converts to 240V, I have to engage a qualified electrician to do the rest.
Looking at the specs online;
Input voltage: 15-95V (cell open circuit voltage)
You can even series 2 panels together to get 75.2 VOC/ 70.2 VMP for longer and small cable runs.
As Big Moe stated the MPPT controller will convert the higher voltage to more amps for your battery bank,.
Now the question of 12v or 24v does depend on what your end state plan is for your solar investment. 24v will be more efficient and allow for more room to grow.
As per my comments to Big Moe, at the moment its just to run minor equipment, who knows one day i might be charging an electric car from the set up. My current setup is probably overkill for what my needs are today, but the longer you wait, the more the cost will increase later on as demand will rise.
Like I stated, It was only because I jumped the gun and brought the 12v Inverter, otherwise I would have set it all up as a 24V system.