Offgrid solar and batteries | Philippines

Hi, We are in The Philippines and I am never listened to by contractors here since I am American. My wife selected a contractor and had 33, 300 Watt panels installed using 2, 4000 Watt, 5000 Watt peak inverters with 60 amp builtin chargers. These are supposed to power 5 inverter type A/C units (we only have 4 online) which draw about 600 Watts each after start up and about 1000 watts of other things total with 36, 200 watt lead acid batteries. I say the inverters should be at least 7000 watt with at least a 12,000 watt surge capacity each.
We built a structure just to mount the panels, I say the requirements for top optimized performance are A Sun, B Alignment (azimuth 180 for The Northern Hemisphere) and C Angle based on our latitude X the appropriate factor. (about 11.2*) But they disagree. The array is partially shaded most of the day, the alignment is off by 12 degrees, and the angle, well, 1/2 of the array points NNW at 20* and the other 1/2 points SSE at 20*.
They say there’s not enough batteries so they added 2 additional chargers to the system because it was shutting down continuously, now the lights flash on and off every few minutes. Sometimes it’s long enough to restart the A/C’s and slows our light timers by about 5 minutes a day. To me the problem seems to be inadequate output from the array as designed. Also our electric bill from the utility is higher now than when we had no solar. What do you think???

Hey there uglydog

Regarding the inverters, it looks like you have about 10kW with 2x 5kW inverters, which sounds fine. What are the brands/ models of the inverters? What makes you think you’ll need 2 x 12kW inverters?

Regarding the alignment of the panels, you’re certainly correct in the ideal being approx 10* south in the Phillipines without shading, however you do have to work with what you’ve got. It’s very rare to have the perfect setup for a solar install. Have you got some pics you could post of the install.

Regarding the power bill, did the air con units get installed at the same time as the solar? They can suck up a lot of power.

I’ll leave the battery question for someone more knowledgeable.

Hope that helps. Would love to see some pics, including the inverter and battery setup.


Hi, The A/C units were in before the solar. We use inverter (DC) type units that stay on, they use less power than regular units as they slow down as the room cools and the compressors don’t cycle on and off so they use about 600 watts each after initial cool down. The reason I feel these inverters aren’t strong enough is, when there is a power outage or one of the constant surges from this system lasts a bit longer than usual and they all restart together they trip the breakers on the inverters. We put 2 A/Cs per inverter, one set we can only use 1 A/C as when the 2nd is turned on the inverter trips out.
The inverters are Must PH1800, hybrid inverters. They are wired so everything runs off the batteries all the time. The electric here is the same as the US two 110 lines making 220. The only thing, everything, lights pumps, A/C is 220 with no ground. Right now we don’t have the refrigerators, well pumps, or the 6 A/C units for the common areas hooked to the solar, they are still on the utility through different meters. A future project is to install about 40 more panels with adjustable mounts, most with mini inverters that will only power the extra A/c units during the day and a few on another inverter and batteries to power the refrigerators and some other stuff. (I’ll do the install myself) I’ll get pics ASAP.



In the center of the left (SSE) row of panels is a solar hot water heater. The panels to the right and left are shaded half the day each, The panels on the right (NNW) side are completely shaded all day except in late June and July. They are wired with the wrong facing panels and the sort of correct facing panels wired together. I think the NNW panels should be removed the mounts raised and then reinstalled so they at least face SSE. All the panels that are shaded should be relocated. What do you think??

Thanks for the photos. It looks pretty cool, but yes I see what you mean, the shading from the hot water is not ideal. I’m assuming there aren’t optimisers installed with the panels, which means the shading could really bring the system performance down. I’m assuming the S and N arrays are wired in two separate strings, it would be useful to see the daily output from each string if you can get it from the inverter?

Regarding the rest of the setup, I’m a little confused on how it all goes together. I think I’d need a line diagram of the whole setup from the electrical workers to understand it better.


Yes, no optimizers. You would think a normal person would install the NNW linked and the SSE linked, but not here. Both sides linked together as you go along the rows of panels. Also, I now noticed the 2 new battery chargers aren’t linked to the solar, they are tied into the utitlity with timers that cycle them on and off every few minutes. I think that may be the cause of the continuous power surges. The reasoning for this, “there is not enough batteries, so they aren’t fully charging”. That 's nuts to me. In the photo of the inverters, you can see the timer in the center, the 2 black boxes with the white across the top and bottom are the new chargers.
I checked the power coming from one of the cables from the array and the output was only reading about 30 volts (48v system) and about 75 amps. at Solar Noon, no clouds. I’ll get one of our electricians to make a diagram, the installers didn’t have one they just hooked it up.
It’s too bad they did this, it’s the first part of what’s planned to be about 70 panels to power the entire property. The entire structure was purpose built, including that room under them just for the solar installation. They could have so easily built it correctly. I’ll get the output, I think one of our electricians understands what he’s looking at on the inverter’s screens, I can’t figure it out.

Just a few observations:

    • you are probably blowing breakers when the A/C units cycle back on after a power surge because they will each draw up to three times their normal power load at start up. This is normal for motors when initially starting.
  1. if there are no optimysers connected to this system, then any shading will affect the entire string of panels, reducing the power output of the entire string.
  2. if, as you say the panels facing opposite directions are on the same string - that is just nuts. One side of the string will always be shaded and bring down the production of the entire string. For example: if one panel is in the shade and its production is reduced by 50%, every panel in the string will also be reduced by 50%. If you install optimysers, they will effectively separate the panels so that the shading of one panel will not affect the rest of the panels on a string.
  3. I see no good reason to have the panels connected in one string when facing opposite directions, even if optimysers are used - it makes no sense.

Good luck getting the system up and running correctly, looks like it will be a really cool system.