Baggywrinkle
Well-Known Member
I have two series arrays of solar panels which deliver 630W each at around 70V ... and as I ran out of time before the 2025 season started, I hooked them directly to the 12V lead acid bank with 2 x Victron MPPTs 100-50 and went sailing. The boat worked great, as long as I made careful use of the 230V kitchen appliances.
Now I have started my Li install and have to re-wire the solar to the 48V system, this involved buying another pair of Victron MPPTs for the 48V side, this time 100-35s. I intended to feed the 48V system into the two now redundant 12V 100-50 MPPTs solar inputs (abuse I know, but I was told by many that it works fine) ... however, as I started thinking about the setup, there were a few things that troubled me ...
1. The abuse of the 12V MPPTs which have voltage and current limits on the solar input - not a couple of 48V Li batteries - what if the inputs get internally shorted?
2. Over winter, the 12V system was very happily on float every day with what little light there was, so I want to keep this feature.
The 48V system is really there to run the inverter and remove the 230V household appliances from the previous 12V inverter. it also needs to charge the 12V system. I had originally only considered attaching the solar to the 48V side and charging the 12V system via a B2B charger - (or the abused MPPTs). Victron doesn't sell an OrionXS 48-12 unfortunately, and the Mastervolt and Sterling alternatives are expensive and a different ecosystem.
But ... the boat already has a 230V 12V 50A battery charger connected to both 12V batteries, starter and house bank, and there is also a 12V 120A alternator to charge them both when the engine is running. So I could just leave the charger fitted and feed it with 230V from the 48V inverter - less efficient, but means no hot B2Bs and I have plenty of solar and lithium.
Then I thought about the solar panel shut-off switch and had a bit of a eureka moment .... what if I replace the solar panel shut-off switch with 2 selector switches? One for each 630W array that can direct the solar array outputs to the 48V MPPTs, the 12V MPPTs or switch them off completely? Then I could have all 1260W directed to one battery system, 48V or 12V, or I could split them, 630W to 48V system, and the other 630W to the 12V system. For a few euros this gives me a way to direct the solar to where it is needed most and covers the winter months where the lead acid discharges.
So that's what I've done .... will be back on the boat this weekend to finish the Li install off. (hopefully)
Wiring now looks like this ....
Solar Arch ....
48V system ...
12V system .....
Now I have started my Li install and have to re-wire the solar to the 48V system, this involved buying another pair of Victron MPPTs for the 48V side, this time 100-35s. I intended to feed the 48V system into the two now redundant 12V 100-50 MPPTs solar inputs (abuse I know, but I was told by many that it works fine) ... however, as I started thinking about the setup, there were a few things that troubled me ...
1. The abuse of the 12V MPPTs which have voltage and current limits on the solar input - not a couple of 48V Li batteries - what if the inputs get internally shorted?
2. Over winter, the 12V system was very happily on float every day with what little light there was, so I want to keep this feature.
The 48V system is really there to run the inverter and remove the 230V household appliances from the previous 12V inverter. it also needs to charge the 12V system. I had originally only considered attaching the solar to the 48V side and charging the 12V system via a B2B charger - (or the abused MPPTs). Victron doesn't sell an OrionXS 48-12 unfortunately, and the Mastervolt and Sterling alternatives are expensive and a different ecosystem.
But ... the boat already has a 230V 12V 50A battery charger connected to both 12V batteries, starter and house bank, and there is also a 12V 120A alternator to charge them both when the engine is running. So I could just leave the charger fitted and feed it with 230V from the 48V inverter - less efficient, but means no hot B2Bs and I have plenty of solar and lithium.
Then I thought about the solar panel shut-off switch and had a bit of a eureka moment .... what if I replace the solar panel shut-off switch with 2 selector switches? One for each 630W array that can direct the solar array outputs to the 48V MPPTs, the 12V MPPTs or switch them off completely? Then I could have all 1260W directed to one battery system, 48V or 12V, or I could split them, 630W to 48V system, and the other 630W to the 12V system. For a few euros this gives me a way to direct the solar to where it is needed most and covers the winter months where the lead acid discharges.
So that's what I've done .... will be back on the boat this weekend to finish the Li install off. (hopefully)
Wiring now looks like this ....
Solar Arch ....
48V system ...
12V system .....
