diy solar

diy solar

400W off-grid system odyssey, 3 inverters dead so far...

Carlos MDC

New Member
Jul 5, 2023
Hello everybody, by watching Will's videos I built my first solar system 2 years ago. I started small with a 150Wp panel and a 30Amp PWM Morning Star EcoPulse charge controller, a flooded 12V battery 150Ah from Trojan (the constant electrolite refilling was a pain, but necessary) and a Giandel 600W pure sine wave inverter. the main purpose of this system was to power the internet setup around my house, a load equivalent to 40 Watts 24/7, and to sustain a couple of 50W fans when we have power outages (I live in Honduras, central America and during hot summers or very heavy rain, Power Outages are very common and annoying).

I soon realized the solar panel was not enough to keep my battery charged with DOD at 50% with the constant 40W load. 1 year later, decided to install a second 150W panel and connect it in parallel to my PWM controler to increase production capacity to 300Wp. During a capacity test at peak solar production time with nice clear skies, I installed a hair dryer that on low settings would load the system with 559 Watts (as measured with my KillaWatt meter) to my system to load it to near max and my Giandel failed to sustain the load. It started whining almost inmediately and, without any alarms or fault state, just wouldn't generate the correct 120V 60Hz and the whine was permanent. It still does when I connect it without alarms of fault indicators. First Inverter down.

After the first inverter was down, I upgraded my PWM controller for the Renogy Rover 30Amps MPPT controller and connected both 150Wp panels in series. Also bought a second 400W modified square wave to get the system up and running until I could find an alternative. 2 weeks later I found a local supplier (via facebook adds) with extreme chinese knockoff manufactured solar equipment with their costumized logo brand. I didn't want to wait 21 days for a replacement inverter so I decided to buy a 1000W Pure sine wave inverter with 6 months warranty. I bought and installed it and it worked flawlessly to my surprise. The output 120V 60Hz was very clean and I was happy. I performed the capacity test with the hair dryer no problems at all, sustained the 559Watt load for 1 hour without any issues, just the noisy fans from the inverter when cooling. 8 months later while at work, I came back to find my Wifi signal was out, I heard a buzzer noise in the background and found the 1000W inverter dead with a Fault alarm LED on. 2 months after the warranty had expired... Second inverter down.

Sooooo second inverter down... Back to the 400W modified wave meanwhile. Decided to go for the Gowise PS1002 1000W inverter on amazon. Waited 21 days to get it to Honduras and installed it, worked as expected. During this time I found that the same chinese knockoff local provider had for sale LiFePO4 batteries, 120Ah 12.8V. Bought 1 to test the quality and it was crap with 1 year warranty. 80Ah in reality and cells were very unbalanced. The JBD regular 64Amp BMS never balanced becuase it requires all cells to be at 2.6 Volts in order to trigger balancing which would never achieve because 1 of the cells had more charge than the rest and would trigger overvoltage protection before the rest could catch up. Did manual balancing by charging to 13.6 and then connecting a 10W ceramic resistor in parallel to the overcharged cell until voltage was similar and proceded to increase charging voltage 0.1V at a time until all cells reached 14.6V so the BMS balancer could kick in. Succes! I was able to achieve about 89Ah... still crap but much better than my Flooded Lead/Acid 150Ah @50% DOD. Also changed the dual 150Wp setup for a single 450W Mono panel to maximize the 400W @12V for the Renogy Rover 30A MPPT charger and it works great!

After the upgrades, I did a capacity test at peak production and the charger could reach 389W from the panel with the hair dryer load of 559W AC on the inverter. Satisfied with the result I let it continue its secondary job for the next 2 months. Yesterday, during a thunderstorm a lightning struck nearby and took down the grid electricity for about 45 minutes. When the lightning struck, the lights went out and the GoWise inverted arced inside for an instance and then it was dead, truely dead without any power or LEDs at fault. All my network setup was running from the APC 1000W UPS I have connected to the offgrid system but my ubiquiti 150W poe+ switch was completely erratic and wouldn't initialize and inject Poe to my APs and my Edgerouter X. All this happened on the AC side of the inverter. On the DC side there was nothing out of the ordinary. the breakers didn't trip, the BMS didn't trip, the charge controller didn't trip and was working fine. all the damage happened on the AC side. Bear in mind that my 450W battery backup is completely isolated from the grid and I do not have a negative ground system to true earth. All neutrals are bonded at the battery terminal and the negative from the PV panel is connected to the negative input at the charger, which I measured and it is also connected to the negative terminal of the battery internally inside the charger. Third inverter down....

So the question that bugs me badly... Is it bad luck or a fault in my system wiring? Something is damaging my inverters. 3 inverters in the last 2 years, from different brands, 2 of which are recommended by Will in his videos. Here is a sketch of the connection diagram for my system: