question

I have recently installed solar panels on my motoryacht. I am now looking for the most economical use of the solar panels, also in order to reduce the cost of shore power. The electrical system has mainly Victron components, except the panels and battery: Quattro 8000/200, Venus GX, MPPT 100/30, 720 Ah tubular plate batteries and 2 x LG Neon R 370 Wp panels, latest firmwares.

I have studied all the manuals and looked for answers on the community site. Although I see similar setups, I still do not have the ultimate answer on how to use the panels the most economical, either by using Ignore AC, DVCC, lower float voltage or a combination of these.

I fully understand how Ignore AC in VEConfigure works and have now set it up according to below screenshot:

I have been to the yacht today and have tested it with several loads. When using heavy load, the Quattro will deliver the power instead of drawing it from the battery, so it does not unnecessarily drain too much, which would take forever for the panels to charge back into the battery. There is a certain amount of equipment that draws about average 200 W, so in a day I will loose 4.8 kW. On sunny days the panels will charge with about 4.8-5.1 kW. So on cloudy days and near winter time the batteries will slowly deplete and when voltage reaches 23.5 V, the Quattro will kick in and charge (with max 100 A) up to when bulk is finished (85 % SOC). I might change that in wintertime to when absorption is finished, as the batteries need to be fully charged every once in a while. So far so good.

The manual of the MPPT states that the DVCC function will result in the MPPT being an active controller in the system. "For systems with lead batteries, DVCC offers features such as a
configurable system wide charge current limit, where the GX device actively limits the
inverter/charger in case the solar chargers are already charging at full power". I have tried the DVCC feature (without Ignore AC) with a setting of 100 A for max charging and shared voltage, current and temperature sense. I have observed the behaviour of MPPT and Quattro for a long time and my impression is that the MPPT does not always do what it should. I can see the Quattro charging with high amps and the panels with relatively low. When I switch off the shore power, the panels immediately jump to a much higher charge, so the panels are under DVCC not used with maximum capacity. I would also expect that when batteries are full and loads are low, while panels can produce more than the load, that the Quattro might stop charging all together.

An expert advised to lower the float voltage of the Quattro with 1 V, After lowering that setting to 26.6 V, I saw this morning at around 08.00 hrs that the Quattro stopped charging. Not completely sure why?

I have gathered my thoughts and I think I have to options: 1) use Ignore AC and 2) use DVCC. With option 1, it will deplete the battery more and I think the panels are used most economical, but I need to make sure the batteries are getting a full charge every once in a while. With option 2, the batteries are kept a full charge (100 %)., but I have the impression the panels are not used to the max and the Quattro will only stop charging when the voltage of the batteries is higher than the 26.6 V. Which brings me to the question do I also need to lower the absorption voltage in order for the Quattro to stop charging when in absorption fase in order to get the max charge out of the panels? I find lowering these setting in contradiction to the DVCC manual: "Limit charge current. This is a user-configurable maximum charge current setting. It works across the whole system. MPPT Solar Chargers are automatically prioritized over the mains/generator".

By the way: I use the AC out 2 of the Quattro for heavy users, with the intention that when I loose shore power (while sailing [do you actually sail, drive or operate a motor yacht?]), it automatically switches of the heavy consumers and I will not unnecessarily deplete the batteries. With Ignore AC while still in the harbour, I loose the heavy consumers as the Quattro needs AC on either AC In 1 (generator) or AC In 2 (shore power). I probably have to rewire the heavy consumers to AC In 1.

My questions:

1) Why does the Quattro stop charging when lowering float voltage when panels are charging?

2) Do I need to lower the float voltage in order for the Quattro to stop charging while enabled DVCC?

3) Why is DVCC not using maximum available charge from the solar panels?

4) Do I also need to lower the absorption voltage while DVCC enabled so the Quattro stops charging in absorption fase to maximum use the charge of the panels

5) Can I, or should I, use DVCC in combination with Ignore AC?

Any comment, suggestions, answers are welcome.

I have also published about the installation of the electrical system and the solar panels on my weblog (in Dutch, but has Google translate button): www.xanthiona.com .