I'm Doug Mycko, owner of SolarMan Consulting. I've worked with Big Island off-grid solar systems since 2006. Troubleshooting is a large part of what I do because an off-grid system has several different power sources and controls interacting at the same time.
When the house loses power, the inverter gets blamed. When the batteries don't charge, the batteries get blamed. When the generator sounds different, the generator gets blamed.
Sometimes that's correct. Often it isn't.
What Does “Solar Repair” Mean on an Off-Grid System?
A complete off-grid system includes much more than solar panels. The problem may be in the PV array, charge controller, inverter, battery bank, generator input, communications, programming, breakers, cabling or one of the loads in the house.
The fastest path to a repair is usually to divide the system into sections and determine where the behavior stops making sense.
Common Off-Grid Solar Problems I Troubleshoot
House Suddenly Loses Power
We determine whether the inverter shut down from low DC voltage, overload, battery BMS protection, AC fault or an internal equipment problem.
Batteries Won't Charge
PV input, charge-controller output, generator charging, BMS limits, programming and actual battery condition all need to be separated.
Generator Runs but Charging Is Weak
The generator may be fine. AC-input limits, charger settings, house loads or lithium battery limits can reduce charging dramatically.
Pump Shuts the System Down
Motor starting surge can expose weak batteries, undersized DC wiring, BMS current limits or insufficient inverter surge capability.
Solar Production Disappears
Array voltage, breakers, wiring, charge controllers, MPPT behavior and programming help isolate whether the problem is PV-side or equipment-side.
One Battery Behaves Differently
Parallel lithium banks can develop communication, SOC, current-sharing or connection problems that aren't obvious from a single percentage display.
Battery Says 100% but the System Still Shuts Down
State of charge is not the same thing as the battery's ability to supply a large instantaneous current.
A battery can report substantial stored energy and still experience voltage collapse or BMS protection when a heavy load starts. That is especially important with pumps and other motors.
I want to see actual battery voltage and current during the failure—not only the SOC number on a screen.
Read: How Much Battery Do I Need for Off-Grid Solar? →
Water Pump Knocks the Solar System Offline
This is common enough on off-grid homes that it deserves its own diagnosis.
A catchment or well pump may draw moderate power once running but demand a much larger current while starting. If battery voltage drops hard during that instant, the inverter can see a low-voltage or overload condition.
Read: Can My Off-Grid Solar System Start My Well or Catchment Pump? →
Generator Runs but Doesn't Charge the Batteries Properly
Generator charging involves several separate limits. The generator has an output limit. The inverter has an AC-input limit. The charger has a charging limit. The battery may have its own BMS charge limit. Meanwhile, the house may be consuming part of the generator's output.
Read: Why Isn't My Generator Charging My Off-Grid Solar Batteries? →
Solar Panels Producing Less Than Expected
Low solar production can have many causes: clouds, shading, dirty modules, a failed string, tripped breaker, wiring problem, charge-controller limitation, battery charge limits or system programming.
The important comparison is not simply today's watts against the total wattage printed on the array. We need to consider weather, sun angle, battery state and what the controller is being allowed to do.
Charge Controller Problems
On component-based systems, the solar charge controller can fail or misbehave while the inverter continues operating normally.
That distinction matters on systems using equipment such as OutBack FLEXmax controllers and other separate MPPT controllers. If the battery isn't receiving solar charge, I look at PV voltage and current before deciding that the battery or inverter is the problem.
OutBack Repair on the Big Island
There are still many OutBack systems operating around Hawaiʻi Island. FX, FXR, Radian, FLEXmax and MATE-based systems can often be diagnosed at the component level.
If the needed repair part remains available and the rest of the system is sound, repair can still make sense. When parts, repeated failures or the overall condition of the system change that equation, then replacement becomes worth discussing.
OutBack Inverter Repair in Hawaiʻi →
Should I Repair or Replace My OutBack Solar System? →
Modern Lithium Battery Troubleshooting
Lithium batteries add another layer to diagnosis because the BMS can protect the battery by changing current limits or disconnecting entirely.
On closed-loop systems, communication between the battery and inverter also matters. A communication problem can affect charging behavior even when the cells themselves are healthy.
Different SOC Readings
One battery may report a different state of charge from the others in a parallel bank.
One Battery Carries More Load
Wiring resistance, connection arrangement or internal battery conditions can affect current sharing.
BMS Disconnects Under Load
A high-current event can reach the battery's protection threshold even with plenty of stored energy remaining.
Charging Suddenly Falls
The BMS may be requesting reduced charging current because of SOC, temperature or cell conditions.
Don't Replace an Inverter Until We Know It's the Inverter
Inverters are expensive. Shipping is expensive in Hawaiʻi. Replacing one because “the power went out” is not a diagnosis.
Before condemning an inverter I want to know what DC voltage it saw, what load it was carrying, what fault it reported, whether the battery remained connected and whether the problem can be reproduced.
When Replacement Really Is the Answer
There are times when repair stops making sense. Parts may no longer be obtainable. Several components may be near the end of their useful life. The customer's loads may have outgrown the original system. Or a repair may cost enough that moving to a currently supported platform becomes more sensible.
Modern choices include integrated inverter systems and component-based options such as the MidNite Rosie. The correct replacement depends on the existing system and what the house actually needs.
Read: MidNite Rosie — A Modern Component-Based Off-Grid System →
Information That Helps Me Diagnose a System Faster
Equipment Models
Inverter, charge controller, battery and generator make/model numbers.
Clear Photos
Equipment labels, screens, fault messages, wiring and breakers.
What Happened
What load was running? Did a pump start? Was the generator on? Was PV producing?
Measurements
Battery voltage, PV voltage, current and any log information available at the time of failure.
Solar Repair Areas on the Big Island
SolarMan works with off-grid customers across Hawaiʻi Island, with extensive experience in East Hawaiʻi where stand-alone power systems and catchment homes are common.
Having Trouble With an Off-Grid Solar System?
Send me the equipment models, clear photos, any fault codes and a description of exactly what the system does when the problem occurs. The more we know about the event, the less guessing we have to do.
Doug Mycko
SolarMan Consulting, LLC
Big Island, Hawaiʻi
808-313-0608
www.SolarManHawaii.com
SolarMan Troubleshooting Guides
Frequently Asked Questions
Who repairs off-grid solar systems on the Big Island?
SolarMan Consulting provides off-grid solar troubleshooting, equipment supply, repair support and commissioning assistance across Hawaiʻi Island. Work requiring licensed electrical installation should be handled by an appropriately licensed contractor.
Why does my solar system shut down when the batteries show charged?
Possible causes include battery voltage sag, BMS protection, inverter overload, poor connections or a large motor-starting event. Actual voltage and current during the shutdown help identify the cause.
Why is my generator running but not charging my batteries?
Check generator output, inverter AC-input limits, charger settings, household loads and battery/BMS charging limits. Any of these can restrict charging.
Can an old OutBack solar system still be repaired?
Many can, depending on the model, failure and current parts availability. Diagnosis should come before deciding to replace the entire system.
Why did my solar production suddenly drop?
Weather, shading, PV-string problems, breakers, wiring, MPPT behavior, battery state and charging limits can all reduce observed solar output.
SolarMan Consulting provides off-grid solar design, equipment supply, troubleshooting, repair support and commissioning. Electrical installation or repair requiring contractor licensing should be performed by appropriately licensed personnel.