locating a Grid Tie that fits the specs of my Solar panel

JohnAR

New Member
Joined
Sep 14, 2021
Messages
5
I am having a bit of a problem finding the right Inverter, First I will give a bit of background. I am retired and Live in the Philippines. The Electrical system is 230 volt single phase, Line to Line not Line to Neutral. My solar panels are Trina Solar 505 Watt (Peak Power Watts) the maximum power Volts are 42.80v, the maximum power amps are 11.69A, The Open Circuit Voltage (VOC) is 51.70v and the Short Circuit Current is 12.28A. so my problem has been finding a Grid Tie Inverter that fits within all the specs, what I have found was just one that happen to be a cheap chinese no name brand model, WVC-700R3 so it was some what cheap so I did a search on how dependable they are, what i found was people said if you keep the watts to around half of what the Inverter is rated you should be ok, I went ahead and order one to try with just one Panel, Second problem on day 3 the Unit just failed, the red light comes on and that is it. The first day I notice the thing gets very hot so I went into the program and adjusted the out put to 70% lowering it from 100%. I knew I was very close to the max on the specs of the Unit focusing on the Open Circuit Voltage (VOC) being 51.70v and the maximum of the unit is 60v. I just can not find a better Inverter, i have look at larger Inverters thinking they could handle the load better but they have a Higher starting Volt than my Panel and if I use two panels I am right back into the same boat. So now comes My Question has anyone ever use a DC-DC Step Down Converter "Buck" between the Panel and Inverter? what I have in mind is a 48v to 36v Buck.
 

meetyg

Solar Addict
Joined
Jun 4, 2021
Messages
513
Yes, I have tried a step-down with a similar micro-inverter, the GTB-1200, but it just makes the MPPT algorithm go crazy.

My problem was that the GTB-1200 was not working as specified, which should support up to 50v panels. But when I installed it, it seems like it has some over voltage protection, and would not accept my 455w (42-45v) panels. The GTB-1200 works OK with some other 36v panels I have.

So I tried to use a programmable DC-DC step down, but it didn't work very well with the microinverter. The microinverter always was searching for the maximum power point and was never able to find it.

I got frustrated from those cheap microinverters, and got me a better one:


This one can handle my 455w panels without a problem and seems to run a bit cooler than my other GTB microinverters (I also have two 600w ones, but one failed after only 3 months of use).

It also has better monitoring software, which displays alot of useful information.
 

JohnAR

New Member
Joined
Sep 14, 2021
Messages
5
Yes, I have tried a step-down with a similar micro-inverter, the GTB-1200, but it just makes the MPPT algorithm go crazy.

My problem was that the GTB-1200 was not working as specified, which should support up to 50v panels. But when I installed it, it seems like it has some over voltage protection, and would not accept my 455w (42-45v) panels. The GTB-1200 works OK with some other 36v panels I have.

So I tried to use a programmable DC-DC step down, but it didn't work very well with the microinverter. The microinverter always was searching for the maximum power point and was never able to find it.

I got frustrated from those cheap microinverters, and got me a better one:


This one can handle my 455w panels without a problem and seems to run a bit cooler than my other GTB microinverters (I also have two 600w ones, but one failed after only 3 months of use).

It also has better monitoring software, which displays alot of useful information.
thank you very much for the information and I will keep that in mind. The invert you recommend cost almost the same as I paid for the 700 watt i have. Right now I have the Inverter out for repair as it is cheap to replace the Diods.
 
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