What you will see
- Battery percentage falls overnight while everyone is asleep.
- A closed shop or office still shows a small load.
- Charge drops even though the main appliances are off.
- The displayed percentage changes suddenly without an obvious matching load.
Why it happens
Some electronics consume standby power when they appear switched off. Routers, security equipment and other devices may also remain deliberately active. Automatic appliances, including refrigeration and pumps, should be included when describing what was left running.
The solar equipment itself uses energy. Solis documents that inverter and battery-management consumption can continue when a battery seems idle. The amount and source of that consumption depend on the equipment and operating state, so there is no universal “normal overnight percentage drop.”
A percentage change is not always a direct measurement of energy delivered to appliances. State of charge is estimated, and some systems correct that estimate as they obtain better information about the battery.
That is why the timeline matters. A gradual decline accompanied by recorded discharge should be investigated differently from a sudden percentage jump. Describe the observed pattern without assuming either one proves a defective battery.
What is still running
Gradual decline, discharge recorded
Real energy use. Find the loads.
Sudden jump, no matching load
Often a correction to the charge estimate. Keep the timeline.
What inverter self consumption means
Even with no load, an inverter keeps its control boards, display, fan, Wi-Fi or data logger and, on many models, its output stage running. That draw is its self consumption.
Two numbers matter, and datasheets use different names for them:
- Inverter standby power or night-time power: what a grid-tied or grid-tied hybrid inverter uses when it is not converting power, for example at night with the battery resting. This is usually very small. As one example, Huawei's datasheet for the SUN2000-5-12K-MAP0 three-phase hybrid lists night-time power below 5.5 W.
- Inverter no load power: what an inverter uses when its AC output is live but nothing is connected. Inverters that keep the house supplied from the battery (as most low-voltage hybrids do during load-shedding or in SBU mode) have to keep the output stage running, so this figure is generally higher than the standby figure.
Our guide to inverter efficiency explains how self consumption fits with the other losses, and how to read an inverter datasheet shows where to find the line.
Why it matters at night
During the day, solar easily covers a few tens of watts. At night, on battery, every watt counts.
Example arithmetic, with round illustrative numbers only: if an inverter draws 40 W with no load, that is about 1 kWh over 24 hours. Over a 10-hour night from the battery, it is about 0.4 kWh, which is 8% of a 5 kWh battery before a single fan runs. An inverter drawing 5 W at night would use about 0.05 kWh over the same 10 hours. These numbers only show the scale; your inverter's figure will differ.
Inverter self-consumption
Idle draw
Inverter uses power to stay on
Night
Comes from the battery or grid
Quick-check table: inverter draining battery at night
| Symptom | Likely cause | Safe owner check | Call an engineer if... |
|---|---|---|---|
| Battery loses a few percent overnight with "nothing on" | Normal self consumption plus small hidden loads | Read battery discharge power in the app at night | Loss is much higher than the datasheet figure suggests |
| App shows load of tens of watts at 3 AM | Router, CCTV, chargers, fridge, standby TVs | Switch off the backup-side breakers one at a time and watch the load | Load stays high with every backup circuit off |
| Battery drops more on backup nights than grid nights | Inverter output running from battery (no-load power) | Compare SOC change on a grid night vs a load-shedding night | Difference is large and the mode was never explained to you |
| Battery discharging even when grid is on | Mode setting (e.g. SBU) using battery first | Note the mode shown on the screen | You want the battery kept in reserve; ask for a settings review |
| Inverter fan runs all night, unit warm | Fan control, high room temperature, or fault | Feel for airflow from a distance; check room heat | Fan is loud, grinding, or unit is hot with no load |
| Battery empty by morning, and it used to last | Higher loads, ageing or settings | See the backup-time guide | Always worth a check |
Safe owner checks: measure your inverter no load power
- Pick a calm night with no load-shedding and note the time.
- Read the monitoring app: battery SOC, battery discharge power (W) and load power (W). Take a screenshot.
- Switch off appliances, not wiring. Turn off TVs at the wall, unplug chargers, switch off fans and lights. Leave the fridge on and note it.
- Switch off backup-side breakers one at a time at the backup loads panel, if you have one and it is safe and easy to reach. Watch the load figure fall. Never open the panel cover. See backup loads panel for how the two boards work.
- Read the battery discharge power with every backup circuit off. What is left is roughly the inverter's own draw, plus any monitoring device and the battery's BMS.
- Compare with the datasheet figure for your model.
- Switch everything back on in the normal order.
- Send the screenshots and the inverter model to your installer.
Do not switch the inverter off and on repeatedly to test it, and do not touch DC or battery cables. If you need to shut the system down, use the order in your manual; see how to restart a solar system safely.
Safety box. If the inverter is hot, smells of burning, or the battery is warm or swollen, stop. Switch off in the manufacturer's sequence only if you can do so safely, keep away and call a qualified engineer.
Hidden loads that look like self consumption
Often the inverter is blamed for loads that are really in the house: the Wi-Fi router, CCTV recorder and cameras, fridge and freezer compressors, TVs and set-top boxes on standby, chargers left plugged in, a water dispenser, AC indoor units in standby, and gate motor controllers. Each is small, but together they can easily exceed the inverter's own draw. Our home energy monitoring guide explains how to find them.
Power-saving mode: useful, with limits
Some inverters offer a power-saving, ECO or search mode. When no load is detected, the inverter turns its output off and wakes briefly every few seconds to check for a load. One manufacturer's documentation describes this cutting no-load consumption by around 85%, with a default wake-up threshold of 15 W.
The catch: loads smaller than the threshold, such as a router, a phone charger or LED lights, may not wake the inverter, and devices that need constant power can switch off. That makes power saving a poor choice for most Pakistani homes where the router, CCTV and fridge must stay on. Whether your model has this setting, and what it is called, depends on the model. Ask your installer before enabling it.
What an engineer will check
- The real no-load figure on your unit, measured on the battery side, compared with the datasheet.
- Mode and priority settings: whether the battery is being used first while the grid is available. See SBU, SUB and utility-first modes.
- Cut-off and low-battery settings, so the battery is not taken too low overnight. See inverter battery low voltage.
- Fan and temperature behaviour: a fan that never stops can mean the unit is too hot or a sensor is faulty. See inverter overheating and why your inverter makes noise.
- Battery and BMS draw, self-discharge and imbalance.
- Inverter size against the load, and firmware.
A measured draw far above the datasheet figure, or a fan running hard with no load, can point to a fault in the unit.
How to prevent unnecessary drain
- Compare no-load and night-time figures on datasheets, not just peak efficiency. Our solar inverter price guide lists the families we supply.
- Size sensibly. An inverter far bigger than your load spends its nights idling.
- Trim hidden loads on the backup side.
- Keep the battery for grid-off hours where your load-shedding pattern allows; ask for the mode to be reviewed.
- Keep the inverter room cool, so the fan runs less.
If backup time has fallen and self consumption is not the reason, see battery backup time reduced and solar battery not charging or draining fast. Off-grid owners should also read off-grid solar inverter, where night draw matters most.
How Solar Works Pakistan helps
For systems we install, our own engineering team handles after-sales complaints. WhatsApp 0336 666 4321 with a screenshot of the app at night and your inverter model. We target sending service personnel within 48 hours of a registered complaint to begin diagnosis; fix time depends on the fault and parts. Our 1-year service warranty applies under the applicable project terms, and equipment defects go through the manufacturer's warranty per product. See how after-sales service works and our solar troubleshooting guide.
We can also check night-time drain and settings on systems installed by other companies, as a chargeable service, across Punjab.
Frequently asked questions
What is inverter self consumption?
It is the power the inverter uses to keep its electronics, display, fan and communication running, even with no appliances on. It is listed on the datasheet as no-load consumption, standby power or night-time power.
Why is my inverter draining battery at night with nothing on?
Partly the inverter's own no-load draw, and often small hidden loads such as the router, CCTV, fridge and chargers. Measure the battery discharge power at night with the backup circuits off to see how much is the inverter itself.
How much is normal inverter no load power?
It depends on the design. Grid-tied hybrids resting at night can draw only a few watts, while inverters keeping their AC output live from the battery draw more. Check your model's datasheet; we do not quote a general figure.
Does inverter standby power show on my electricity bill?
On a grid-tied system, any standby draw at night comes from the grid, but it is small. On a battery system it comes from the battery, so it shows up as shorter backup rather than on the bill.
Should I switch off my inverter at night to save power?
Usually not. You lose backup and monitoring, and repeated switching is not good practice. If night drain is a real problem, ask your installer to review settings or check the unit.
Can I turn on power saving mode on my inverter?
Only if your model has it and your night loads suit it. Small loads like routers may not wake the inverter, so essential devices can switch off. Ask your installer first.
Sources
- Huawei, SUN2000-5/6/8/10/12K-MAP0 datasheet (night-time power, off-grid output, switchover with SmartGuard)
- Victron Energy, "ECO mode and ECO settings" (how search/power-saving mode reduces no-load consumption, wake-up threshold)
What you can check yourself
- List equipment left connected overnight, including CCTV, internet devices, refrigeration and automatic pumps.
- Record the starting and morning battery readings with their timestamps.
- Save battery-discharge and property-load graphs covering the same period.
- Note whether the grid was available and whether a timed discharge period was active.
- If safe, turn off nonessential devices using their normal controls and record the effect on the displayed load.
- Do not interrupt security, refrigeration, medical or other essential equipment just to make the reading reach zero. Tell us which loads must remain running.
What not to do
- Do not disconnect battery cables, operate unidentified breakers or open a distribution board to hunt for a hidden load.
- Do not repeatedly reset the battery percentage or change its capacity setting.
When to call us
- Contact us if the decline is unusually large compared with previous similar nights, displayed load remains unexplained, or abrupt charge changes repeat. A review can separate appliance consumption, system consumption and reporting behaviour.
Overnight checks in Faisalabad and Lahore
Shops and offices in Faisalabad and Lahore often leave CCTV, routers and refrigeration running overnight. Tell us which loads must stay on, and our team will separate them from system use and reporting.
Send us
The inverter and battery models, overnight graphs, devices left running, grid-availability details, and your city and area.
Technical references
Reviewed 25 September 2026. Manufacturer documents are cited for general principles; your exact model’s manual always applies.