Using a step down converter before the charge controller

[Earther]

So my panel is 330w with a rated open voltage rating (I think that's the right term) of either 58 or 62 volts. Either way on the absolute sunniest of days I've never seen it reach 60, in fact 56.8 is the record high for this panel.

so that being said I am poor and am trying to do this as cheap as possible. I live in a bare bones shipping container, if that clues you in to my situation.

so since any charge controller I come across that even comes close to handling that type of voltage is easily over $100. I can afford that. Hell the way I'm asking here I can't really afford but I'm going to try like hell.

so can I take a step down controller that goes from let's say 48v (they are rated to handle up to 63v from what I've seen) to 24v and wire that into a charge controller rated for up to 32v?

if not why? And what's your best money saving idea on how to do this

[SunEagle]

So my panel is 330w with a rated open voltage rating (I think that's the right term) of either 58 or 62 volts. Either way on the absolute sunniest of days I've never seen it reach 60, in fact 56.8 is the record high for this panel.

so that being said I am poor and am trying to do this as cheap as possible. I live in a bare bones shipping container, if that clues you in to my situation.

so since any charge controller I come across that even comes close to handling that type of voltage is easily over $100. I can afford that. Hell the way I'm asking here I can't really afford but I'm going to try like hell.

so can I take a step down controller that goes from let's say 48v (they are rated to handle up to 63v from what I've seen) to 24v and wire that into a charge controller rated for up to 32v?

if not why? And what's your best money saving idea on how to do this

First off the panel Voc is measured when the panel is not connected to anything but is in sunlight.

What is the make and model of that 32v CC? Maybe it can handle the output from that 330watt panel.

My suggestion is don't spend money on a step down device. Put that money toward a better charge controller. It does not have to be expensive to get something out of that 330 watt panel. It just needs to have a higher Amp rating then the Isc of that panel.

Now a cheap PWM CC will not convert 100% of the panel wattage to charging current but it will get you about 67%. A more expensive MPPT CC will convert just about 100% of the panel wattage to charging current but you don't have to start out with one if you can't afford it.

[Sunking]

You have a panel made for Grid Tied applications and can easily be used to charge a 12 volt battery. In order to do so you must use a MPPT Charge Controller, or what you are calling a Step Down Converter. With a 330 wat panel requires at least a 25 amp MPPT Controller and those will cost at least $200 for a real MPPT Controler.

If you used a cheap Chi-Com or PWM controller you turn your 330 watt panel into a 80 watt panel. The reason you are not seeing the panel reach 60 volts is because it depend on temperature, and is negative coefficient meaning the warmer the panel is, the less the voltage is open circuit. With a proper MPPT Controller, the panel will operate at Vmp which is 20% lower than Voc. So if you see 58 volts means the panel is open circuit and not generating any power.

Sorry about your current situation, but solar is what it is. Extremely expensive luxury.

[jflorey2]

So my panel is 330w with a rated open voltage rating (I think that's the right term) of either 58 or 62 volts. Either way on the absolute sunniest of days I've never seen it reach 60, in fact 56.8 is the record high for this panel.

Sunny is not the thing that drives voltage highest. It's cold. Voltage goes up as it gets colder.

so can I take a step down controller that goes from let's say 48v (they are rated to handle up to 63v from what I've seen) to 24v and wire that into a charge controller rated for up to 32v?

Nope. You will "collapse" the panel, since you are feeding into a negative impedance input (a DC/DC converter.) Your options are:
-cheap MPPT controller
-build it yourself (but if you are asking questions like the above that's likely not a good idea.)
-24V system and only get about 100 watts out of the panel.

[Earther]

So if I took two deep cycle marine batteries and wired the together to make them in essence a single 24v DC battery and used a controller that covers my output voltage to 24v to charge the batteries and then after or even during daytime I can just disconnect the solar and disconnect the two batteries from one another and hook them up as 12v independent batteries to run my 12 volt needs?

yes? No? Why?

holy run on sentence batman.

[jflorey2]

So if I took two deep cycle marine batteries and wired the together to make them in essence a single 24v DC battery and used a controller that covers my output voltage to 24v to charge the batteries and then after or even during daytime I can just disconnect the solar and disconnect the two batteries from one another and hook them up as 12v independent batteries to run my 12 volt needs?

Yes, you could do that. I would be very concerned over the chances of misconnection if you do that every day. Remember, if you short battery cables there is no protection; burns, fire and/or explosions are not unlikely.

If you are going to do this, use a foolproof connector setup (i.e. no way to connect it incorrectly) or a high current switch.

[sensij]

If you treat them as independent 12 V batteries for discharge, but charge them 24 V in series, they will be out of balance. The battery with shallower discharge would top off first and limit the current into the more discharged battery. If you hooked them in parallel while discharging so that the discharge was even between them, it would probably work better, but as jflorey2 alrady pointed out, that is a lot of switching hard to do safely.

[Sunking]

You cannot balance the batteries as Sensij eluded to. Ignore anyone who says it can be done if...