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.

Hi, Sorry it took so long to get back to everyone… Yes it was constantly tripping breakers and burning wires. The more I looked, the more messed up everything is. Not only is everything I previously mentioned wrong, here’s some new discoveries. Some of the panels aren’t even hooked up. All connections between panels are made with pre-made wires, which are way too long, hence loops at every connection. The main cables, which I figure should be no less than 4 gauge are about 14 gauge shielded extension cords which are also way too long and looped an extra 10 times on their way to the inverter adding an extra 25-30 ft to their length, and then, (you’re gonna love this) run through 125 amp a/c breakers! Not d/c! The batteries are a combination of 100 amp and 200 amp wired together! Totally NUTS!
Since we are installing another array of 40 panels ( I am myself no contractors this time), we decided to take the entire mess down and do it right, full sun from 6 AM to 6 PM, Azimuth alignment and adjustable panels at -2* Summer, 15* Spring and Fall, 30* Winter. Here the electricity is so expensive we figure a system which operates correctly will have a payback at about 2-3 years. I’ll put on some pictures later today.

Wow, that is nuts. Good look, very keen to see the photos.

Thanks for the update.

Here’s some pics of the project so far. We triple checked alignment, 1. shadow at solar noon, 2. shadow at sunrise and sunset, 3. a map alignment based on our location gps. All match exact. We are raising the panels so they get full sun from sunrise to sunset, no shadows, no shade. We made a simple adjuster mechanism for each mount of 2 panels with hitch pins and 3 holes in 2 angle bars for seasonal adjustment. The first 2 pics are the mounting frame, all heavy duty galvanized tubing cross braced, the last pic is a mount for 2 solar panels. The mounts are made of steel angle bar primed and painted with epoxy. We are using 40, 360 watt panels on this part with a 12,000 watt inverter with a surge capacity of 36,000 watts. I’m planning on letting the inverter clip the extra watts from the 14,400 the panels will produce to extend the maximum power production time. The 30 old panels will be remounted correctly and run through a 9,000 watt grid tie inverter with a surge capacity of 27,000 watts set for zero export to run the main house aircon units which will be wired through water heater times to run only during solar power production. Hell of a project for a first timer!

I do have a question, if anyone knows. Our new main inverter works at 96 volts. The batteries, some are 100 ah, some are 200 ah, I’d like to use all of them, ( I figure they’re all probably messed up being wired together for 9 months already) would it work OK if I wired sets of 8 of the 100 ah, to make 96 volts and sets of 8 of the 200 ah to make 96 volts and put them in parallel on the same charge controller, until I have enough extra cash to replace them all with a matched set? I figure the worst that would happen is the 200 ah batteries would not cycle as deep as the 100s.

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Ooh, getting serious now. I like it!

@SolarHybridSolutions might be able to help you out with that question about the batteries @the_uglydog. What you’re saying sounds about right to me, but I’m pretty hopeless with batteries.

Looking forward to seeing the end result.

You can install an Energy Monitoring system that measure Power you draw from grid as well the power you consumed to get the general picture of the system,

The batteries before they are wired up in series to form the 48V or even 96V , each individual battery must be verified with a battery tester, to ensure compatibility with each other, of course No different brand or rating in the battery string

Another consideration EVEN when 2 identical battery banks are put in parallel , there should be a battery balancer circuit installed so as to keep both battery bank approximately at the same charge level

Perhaps , would be good idea to replace the battery with LiFePO4
that come in modules and in your case ,better to deploy a 120v battery sys and a Selectronic Inverter

Esmail of Solar hybrid Solutions

This is not a good situation. The two different batteries will have different internal resistance and not charge at the same rate. I expect this would become unbalanced after a few cycles or worse the 100Ah battery string might go ‘over-voltage’ and damage the batteries. I suggest you monitor the charging cycle very closely and ensure there no dangerous situation or thermal runaway.

You should also have each battery bank fuse protected using HRC fuses (NH00 - 125A or 160A).
I might be necessary to charge each battery bank separately to be safe?

Hi, Thanks for the responses. The charge controllers I am going to use, are all the same and are compatible with multiple battery banks and are designed to be connected together in parallel. They equalize themselves at the set voltage when connected together, I was planning on grouping the batteries of the same amps on the same controllers. The charge controllers and the inverters all have temperature sensors so the temperatures should be OK. I tested all the batteries and they seem about the same and are from the same manufacturer. That’s a great suggestion to fuse each bank individually. The controllers and the inverters I am using all have the function to communicate with each other and record and display reading from input of solar and grid and output of each string of panels.
I was wondering if it would be a good idea to use dielectric grease, like what’s used on the connections of spark plugs, on the MC4 terminals to seal them or are they good to go as is?
A few other interesting things we found. The extension cables they used from the panels to the inverters are only 14guage ALUMINUM wires! Those were connected with copper connectors. (all of them corroded of course!) The battery cables are only thin ALUMINUM cables connected with copper connectors (all corroded as well!). The panels were connected with 2mm2 thin strand copper wires, not the 4mm2 thick strand copper that comes on the panels and not even PV cables and a lot of the insulation was already deteriorating and a number of the MC4 connectors were corroded from not being plugged in correctly.
I think Moe, Larry and Curly must have done it!!

The MC4 connectors are designed to be connected dry and without any greese. I would not recommend using any lubrication. If the terminals have corrosion they should be replaced.

Also there are several different types MC4 connectors available and some are not compatible. You should try to only use original or genuine MC4 connectors (see below)


Haha yeah it sounds really dodgy. The solar DC cable (4mm2 tinned copper) must be used or there will be issues as you have seen. Lucky you fixed this or it could have started a fire.

Hi, Yes. Especially since the breakers were 125 amps! The connectors I got are compatible with all of the old ones as well as the new ones. I do have another question. I’m installing combiner boxes with 500 volt and 20 amp breakers per string. The wiring diagram seems to say to connect the - side of the panels to ground as well as to the inverter and to connect the lightning arrester breakers to the same ground and the box to the same ground. Am I reading that right? I was thinking of grounding them to the galvanized steel tubing the structure is built from which is welded to the building rebar and then grounding that connection to a copper rod driven 10 ft into the ground making sure all the wiring for it slopes toward ground. The structure will also have lightning rods with grounds connected to the steel tubing, located about 30 ft from the combiner boxes and the grounds for the boxes. For the wires from the boxes to the inverters I’m planning on using 8mm2 regular wire inside conduits, that should give me less than a 2% loss. Does this all seem right?