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dsprygada avatar image
dsprygada asked

Battery voltage allowed by mppt 100/50

I have 6-75 W siemens solar panels. The maximum voltage while the sun is charging his only 12.4 v. When the sun goes down it drops to 12.1 or 12.2 V. I have 630 amp hour battery bank which is brand new. My old trace control charger would allow upwards to 14.5 V and when the sun went down it would settle at 12.5 to 12.6 V.

My daily output is about 1.3 kW. Max wattage about 265 w .

Should I be receiving higher voltage from these panels?

Is the charge controller limiting the voltage coming in to the batteries to the 12.4 max during absorption phase?

Are there settings that would allow more energy from the panels to reach the batteries?

MPPT Controllers
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dsprygada avatar image dsprygada commented ·

Correction. Max voltage in 12.4 during "Bulk" phase.

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Jonathan Phillips avatar image Jonathan Phillips commented ·

It seems that your battery will become damaged quite quickly if you do not alter the voltage from your PV array. Are they connected in series? Most PV panels will output anywhere from 13v to 20v and if they are connected in series (6x12v) you could receive up to 120v max. I have the same charge controller as you connected to 3 x 12 v panels connected in series which supply anywhere from 54-60v. The minimum float charge your 12v battery bank should be sitting at would have to be 12.73v depending on the type of battery you have. I have pasted a chart supplied by Trojan batteries below (lead acid). I hope some of the info helps.

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2 Answers
wkirby avatar image
wkirby answered ·

How did you configure your solar panels, like how many series / parallel?

What Voltage can you see on for PV from the charge controller.

Remember, MPPT charge controllers need to have PV Voltage higher than the battery Voltage. It needs to be 5V more than battery Voltage to start and then it needs to be 1V more to keep charging.

Higher PV Voltage will be better, then it can wake up earlier in the morning and make power later in the afternoon.

You can have PV up to 100V with your charge controller.

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lee avatar image
lee answered ·

See WKirby's answer. Your panels probably have a voltage of about 20V. Thus take 3 panels and connect them in parallel and the same with the other 3. Then take those (they will each look like a 225W panel) and series them together. Thus you will now have about 40V. This way your wire will have less of a drop and your system will "Wake up" earlier. Another option would to parallel 2 panels 3 times thus making it look like 3 150W panels and increasing the voltage to 60V. Either way should work for you. Just that each virtual panel should have the same voltage and each panel within a virtual panel should have the same current for best results.

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