question

Hi @Mariorda91

What model MPPT do you have?

And what is the make and model of the solar panel?

Also please read the solar section of Victron Wiring Unlimited so that you are familiar with parallel and series connections and when it is beneficial to use them.

Keep in mind that for optimum performance there should be at least 5V margin between battery voltage and solar voltage.

There is also an MPPT training video available for free on Victron Professional Online Training.

Hi, your solar voltage is too close to you battery voltage. Please connect 2 in series and 2 in parallel.

Hi @Mariorda91

From your link, the Vmp of those panels is listed as 17.9V. Yet the mppt has tracked 14.56V. This suggests poor light. This isn't a continuous process, likely happening every 10 minutes. So may be hard to nail down without patience.

Or there's a fault somewhere.

A couple of others have already answered that the Voltage is not sufficient - make sure your MPPT is programmed correctly for both your Batteries, and Panels - it needs to reach +5v above your Battery voltage in order to operate. Specifically for instance different Battery types have different Float, Bulk and absorbtion values that should be set first.

Something which the MPPT controllers should be capable of doing is running a Serial PV down to Parallel Batteries. i.e Someone has already suggested putting 2 S x 2P for your panels. This will raise the input voltage significantly, and get you a Longer period of PV input also. Since your Batteries sitting at say 12.88v - With only mid Morning Sun, you will find the panels in Series will probably reach the value needed to Commence charging, and with the Parallel circuit this delivers the Extra current. Overall the total value of Power from the panels is the same, it's just that the MPPT will react and work better this way to achieve what you need.

Hi there,

The answer is really quite simple, everything is actually working exactly as it should. You might do marginally better with series/parallel wiring, but really that is a red herring, and I doubt you would notice a lot of difference overall, and certainly not in the middle of the day.

100W panels will yield 100W in ideal (nominal) conditions, that is 1000w per square meter irradiance and panel temperature of 25deg C. This implies a perfectly clear sky (no haze at all), a cold windy day ( panels easily go above 60 deg C in full sun) and panels oriented exactly at 90deg to the sun. Only then can you expect to get 100W from the panel.

You were seeing 274W from your 400W array? Panel voltage was 14.56, a voltage selected by the mppt as optimum, which implies the panels were hot. (The mppt would have held panel voltage at 17.9 if at 25 deg) Assuming your panels were perfectly oriented, then you would expect a maximum of 14.56/17.9 × 400W (=325W) from your array. Allowing for less than perfect orientation, and an hour past noon, I think 274 W is a very respectable result!!!

Just for comparison, here in Australia in mid winter, with flat mounted panels and coincidentally a 400W array, I typically see between 150 and 180W at midday, and am very happy to get that!

Cheers, Leslie