domestic grid solar panel to charge 12v dc

Chris1234

I have an  older timber cruiser, perminantly moored which requires intermittent use of a bilge pump. I have  a few bilge pumps for reliability and backup, but the basic power system on the boat is powered by a single N70 12v battery. I currently have an older Solarex  40w panel which has lost capacity and needs replacement. 
However, I do have some 190w x 48v domestic grid panels surplus after upgrading my home grid system and was wondering if I could use a transformer to drop the voltage or do I need a specialized controller?
Perhaps not possible at all...
I have reasonable 12v knowledge, but not up to date with full electronic and electrical jargon.
It seems silly to pay for a new 12v panel if I can convert a 48v panel at minimal cost
Thanks

Photowhit

You can use a MPPT type charge controller to drop the voltage and correctly charge your battery bank.

They are NOT inexpensive. Seems I heard recently of a couple other marine sealed charge controllers, but I would generally recomend a Midnite Solar Kid inverter.


https://www.solar-electric.com/midnite-solar-kid-marine-mppt-solar-charge-controller-black.html

Charge controllers are rated at output amperage, so you might want too use Midnites's string sizing tool to figure out how many panels you could put on it.

https://midnitesolar.com/sizingTool_kid/index.php

Chris1234

Thanks ill check it out

mike95490

you CAN use a simple PWM charger with your 48V panels. but the charger must be rated to the Voc of the panels.  You will not get the full  190 w , but only will harvest the amps the panel can produce.