necrolingus

Thanks everyone for your replies! Definitely solutions I did not think about but will investigate, especially the relay mentioned by @Scorp007 For now the diode will have to do until I get around to a better solution.

Thanks! It's definitely the panels draining the battery overnight, already tested it over the last few days.

Hi @Scorp007 Thanks for the reply. The panels have the following ratings (I have 2 of them connected in series): Brand: Fivestar (two old 265 watt panels) Pmax (Maximum Power): 265W Vmp (Maximum Power Voltage): 32.4V Imp (Maximum Power Current): 8.96A Voc (Open Circuit Voltage): 39.3V Isc (Short Circuit Current): 9.47A Maximum System Voltage: 1000V Maximum series fuse: 15A

Hi everyone, and happy holidays! I'm helping my dad connect 2 of his old solar panels to a Mercer Axpert 3000VA inverter. Everything works well except that it seems that neither the panels nor the inverter's MPPT has a blocking diode installed so the battery of course drains during the night. I Google'd but I cannot seem to find any blocking diode products available locally. From what I could find, it seems like this diode (https://www.digikey.co.za/en/products/detail/smc-diode-solutions/15sq100/6022445) should work (it falls within the voltage and amp ratings), and I guess I can install it in an MC4 holder on the positive side? (It is only 2 solar panels connected in series). I am not 100% sure if I am correct... any advise will be greatly appreciated!

Thanks Scorp007! I will have to read up a bit about that,sounds rather interesting. But perhaps a single high wattage panel will be best, less hassle in the long run.

Thanks everyone for your fast and valuable input! I really appreciate it. Ok cool, then I will connect the 2 panels in parallel and monitor the output voltage. If that does not work I will look into rather getting a single panel with the correct voltage.

Good morning. I need some advise please. I have a Mercer Axpert 3000VA inverter. According to its manual these are the ratings for its MPPT controller: Max PV Array Open Circuit Voltage: 75v PV Array MPPT Voltage Range: 30 to 60v I then have 2 solar panels with the following specifications: Optimum operating Voltage (Vmp): 30.6v Open Circuit Voltage (Voc): 37.7 If I connect the panels in series I am worried that I might be over the maximum MPPT values and might damage the inverter because: 37.7 (panel Voc) * 2 = 75.4v -- MPPT maximum raring is 75v. 30.6v (panel Vmp) * 2 = 61.2v -- MPPT maximum rating is 60v. I understand that warm weather, cable length, etc will drop the voltage of the panels slightly but I feel I am super close to the upper limits and I am worried I might damage something. But if I run the panels in parallel , then I am super close to the lower limits again.... I am not sure what will happen if I go over the upper MPPT limits (or below the MPPT limits) and don't want to risk breaking something. I unfortunately only have these 2 panels at the moment and would like to use them if possible. Any advise will be greatly appreciated.

Thanks Scorp007 and Coulomb, I appreciate your explanations and both do make a lot of sense! Not to worry then, seems that this is just something I will need to live with then until I upgrade. Not a big issue though, I could perhaps just assume a 100 watt load for now when there is no reading on the load, should be accurate enough.

Thank you Chris. I checked my inverter's firmware and it is U1 02-73, I guess this limitation is then on my firmware version as well. I scoured the internet for firmware updates for the 3kva version, but couldn't seem to find anything, only for the 5kva inverter.

Hi everyone I've had a Mercer Axpert 3kva for just over a year now and since I got it it never registered low loads. Only when the load is above about 200watt or so does the little LCD display register a load. I also checked using the WatchePower software that came with the inverter (using USB cable) but small loads just does not register. The inverter (and WatchTower) just shows 0 load. I've been through the manual but can't seem to find anything related to this. It would be great to see small loads as well because most of the time during the day the loads will be less than about 200 watts. Or is this perhaps an inverter thing? Thank you

Thanks for the super quick reply and the valuable insight. The current batteries are about 2 weeks old now so still fresh. I'll make sure to get the same make and model. Let me read up on the Victron BMVs a bit. Thanks!

Good day everyone I recently purchased the Mercer sol-i-ax-3m plus 24 inverter with 2 12v deep cycle batteries (105ah) in series (it is a 24v inverter). So far everything works well. I was wondering if I can connect 2 additional batteries (2 in series for 24v, and then another 2 in parallel) so I can run for longer on battery power? Do I have to get a BMS if I want to do this because in my mind all batteries will get charged to the same voltage, but what if a battery is damaged and it cannot charge to the correct voltage? Perhaps I am overthinking this but I figured it will be better to ask someone with way more experience than me before I pull the trigger and buy 2 additional batteries. Best regards