I have a new Victron MP II, Lynx Shunt, Cerbo GX, MPPT with one panel, and LifePO4 installed on a boat for about the last month or two. The MP is running on Solar Priority. Ive noticed the VRM Consumption numbers dont add up. I really wish they would because I would like to have a better idea of daily consumption so I can properly size up my solar (I need more).
You can see in the summary it shows 2.2 kWh from grid, 0.8 kWh from solar, but somehow 1 kWh Consumption Total. Where are these numbers coming from? I can get a realistic total solar yield out of the Advanced data. But I cant seem to get a realistic total AC consumption that makes sense. Searching this site pulls up others with similar issue, but different setups. No real answers. It would be great if I could see how much grid energy is going to charge the batteries and how much is going to the AC bus.
The system does not count its own self consumption (and some inverters are inaccurate uner a 4A load) and losses to heat in DC or AC are not measured and some for battery balancing. Then there is rounding and power factor.
A rough rule of thumb for solar sizing is total daily consumption (divided by number of solar hours - not daylights hours. Adjusted or averaged over the year) adjusted for expected average irradiation.
For example.
On average i have 5 solar hours a day.
I expect to use 5kw in 24 hours running 2 fridges. So 1kw per vour needs to be made per hour minimum.
However, the average irradiance data shows 5.6 so i am expecting close to 60% installed capacity on average. Which means i need 1.6kw of solar installed to be comfortable for the average day.
You are correct and I have looked at the Consumption drop down. Its still not right. The graph shows what looks right for the AC consumption, but the Solar and Battery consumption are very low to zero, which is not right at all. The DC side of my boats electrical is running a freezer and refrigerator as well as all of the pumps and fans.
The main overview display looks perfect, showing current AC and DC input and loads. Its just these graphs and consumption totals that are not making sense.
Thank you, and I may resort to your method of estimating my solar requirement. However, the VRM has all the data. I should be able to see a reasonable tally for daily, weekly, etc consumption totals and for some reason the VRM isnt doing it.
The main overview display looks perfect, showing current AC and DC input and loads. Its just these graphs and consumption totals that are not making sense.
