<!– –>{ “@context”: “https://schema.org”, “@graph”: [ { “@type”: “Article”, “headline”: “Solar Battery Not Discharging — Diagnose Why It Won’t Power Your Home”, “description”: “Battery has charge but isn’t powering your home? This covers every common cause — system mode, minimum SoC reserve, discharge windows, CT clamp direction, grid overvoltage, and BMS faults.”, “url”: “https://solar-tech-support.co.uk/problems/battery-not-discharging/”, “datePublished”: “2026-03-19”, “dateModified”: “2026-03-19”, “author”: { “@type”: “Organization”, “name”: “STS Solar Tech Support”, “url”: “https://solar-tech-support.co.uk” }, “publisher”: { “@type”: “Organization”, “name”: “STS Solar Tech Support”, “url”: “https://solar-tech-support.co.uk” } }, { “@type”: “HowTo”, “name”: “How to diagnose a solar battery not discharging”, “description”: “A structured diagnostic process to identify why a charged solar battery is not powering the home — covering system mode, SoC reserve, discharge windows, CT clamp direction, grid overvoltage, and hardware faults.”, “url”: “https://solar-tech-support.co.uk/problems/battery-not-discharging/”, “step”: [ { “@type”: “HowToStep”, “name”: “Check the system mode setting”, “text”: “Open your monitoring portal or inverter app and check the current system mode. In Eco Mode or Self-Consumption mode, the battery will only discharge when there is active house demand that solar cannot cover. If there is no solar and loads are low, the battery may appear not to discharge. If you want the battery to discharge at a set time — to power the home during peak-rate electricity periods — you need Timed Discharge or Time of Use mode configured correctly.” }, { “@type”: “HowToStep”, “name”: “Check the minimum SoC reserve”, “text”: “Find the operating range or minimum SoC setting in your portal. Many systems are configured with a minimum reserve of 10–20% — the battery will not discharge below this level. If the battery is sitting at or near the minimum, it is working correctly — it is simply at its floor. If the reserve is set too high (e.g. 30–40%), the battery stops discharging too early and the majority of stored energy appears inaccessible. Reduce the minimum SoC if appropriate.” }, { “@type”: “HowToStep”, “name”: “Check the discharge window if using Timed Discharge”, “text”: “If you have configured Timed Discharge or Time of Use mode, verify the discharge window times are correct for your intended peak-rate period. Also check the inverter clock — if it is running on UTC when the UK is on BST, the discharge window will run one hour out of phase with your electricity tariff, causing the battery to sit idle when you expect it to power the home.” }, { “@type”: “HowToStep”, “name”: “Run the CT clamp live load test”, “text”: “Turn on a kettle and watch the grid import reading in your monitoring portal. It should rise by approximately 2,000–3,000W. If it falls, stays flat, or moves in the wrong direction, the CT clamp is reversed — the inverter cannot correctly read house demand and may suppress or misdirect the discharge. A backwards CT clamp is one of the most common reasons a battery has charge but does not appear to power the home.” }, { “@type”: “HowToStep”, “name”: “Check the event log for grid overvoltage events”, “text”: “Open the event log in your monitoring portal and look for grid overvoltage alerts or ‘grid fault’ events. When grid voltage exceeds the inverter’s safety threshold — typically above 253V — the inverter suspends export and discharge as a protection measure. Overvoltage events are most common during low-demand summer afternoons when the local network is saturated with solar export. This is an external grid condition, not a system fault, though persistent overvoltage warrants a DNO complaint.” } ] }, { “@type”: “FAQPage”, “mainEntity”: [ { “@type”: “Question”, “name”: “Why won’t my battery discharge at night?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “The most common causes are: system mode is set to Eco Mode which only discharges reactively to cover demand, not proactively; the minimum SoC reserve is set too high so the battery stops early; the discharge window times are wrong or out of phase with your tariff; or the CT clamp is reversed so the inverter cannot read house demand correctly. Check in this order.” } }, { “@type”: “Question”, “name”: “My battery shows charge but isn’t powering my home — why?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “If the battery shows charge but the home is drawing from the grid instead, the most likely causes are: the system mode does not have an active discharge instruction for that period; the CT clamp is reversed, meaning the inverter cannot see the house load; or the minimum SoC has been reached and the battery has stopped discharging. A reversed CT clamp is particularly common and causes the discharge energy to appear to flow to the grid rather than the home.” } }, { “@type”: “Question”, “name”: “What is the minimum SoC reserve and how do I change it?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “The minimum SoC (state of charge) reserve is the lowest level to which the battery will discharge. It is typically set between 10–20% to protect battery longevity. You can usually find and adjust it in the operating range or system mode settings in your inverter app or portal. Reduce it carefully — going below 5–10% consistently will accelerate battery degradation over time.” } }, { “@type”: “Question”, “name”: “Why does my battery stop discharging at 20%?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “The battery has a minimum SoC reserve set to 20%. This is deliberate — either configured by your installer to protect battery cell longevity, or set as a default by the manufacturer. The battery is functioning correctly. If you want to use more of the stored capacity, lower the minimum SoC setting in your system mode or operating range configuration. Be aware this increases cycle depth, which can affect long-term battery health.” } }, { “@type”: “Question”, “name”: “Could grid overvoltage be stopping my battery discharging?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “Yes. When grid voltage rises above the inverter’s safety limit — typically 253V — the inverter suspends discharge as a protective measure. This is most common during sunny afternoons in summer when local grid voltage is elevated by other solar exports on the same network. Check the event log for overvoltage or grid fault entries. Persistent overvoltage events should be reported to your DNO.” } }, { “@type”: “Question”, “name”: “My battery is discharging but my grid import isn’t falling — what’s happening?”, “acceptedAnswer”: { “@type”: “Answer”, “text”: “If the portal shows battery discharging but the home is still importing from the grid, the most likely cause is a reversed CT clamp. The discharge energy is being measured incorrectly — it may appear to be flowing to the grid rather than the house. Run the live load test: turn on a kettle and watch the grid import figure. If it moves in the wrong direction, the CT clamp is the cause.” } } ] }, { “@type”: “BreadcrumbList”, “itemListElement”: [ { “@type”: “ListItem”, “position”: 1, “name”: “Home”, “item”: “https://solar-tech-support.co.uk/” }, { “@type”: “ListItem”, “position”: 2, “name”: “Problems”, “item”: “https://solar-tech-support.co.uk/problems/” }, { “@type”: “ListItem”, “position”: 3, “name”: “Battery Not Discharging”, “item”: “https://solar-tech-support.co.uk/problems/battery-not-discharging/” } ] } ]}
Battery fault · All brands
Solar battery not discharging
Battery has charge but the home is still drawing from the grid. Not discharging at night. Stopping too early. In the majority of cases this is a system mode setting, a minimum SoC reserve, or a CT clamp issue — not a battery hardware failure.
Work through the checks below in order. Most cases are resolved without an engineer.
Usually a settings or CT clamp issueAll brands affectedHardware failure is less common
Battery still not discharging after the checks?
A remote diagnostic session reviews your portal data live — system mode, discharge history, CT clamp readings, and event log — and confirms the exact cause.
Eco Mode only discharges reactively when house demand exceeds solar. It does not proactively power the home at night. For scheduled discharge you need Timed Discharge or Time of Use mode.
Minimum SoC reserve too high
The battery stops discharging when it hits its minimum SoC floor. If this is set to 30% or higher, a large share of stored energy appears locked away. Find and lower the operating range minimum in your portal settings.
CT clamp installed backwards
A reversed CT clamp means the inverter cannot correctly read house demand. The battery may appear to discharge but all energy flows to the grid rather than covering home loads. See CT clamp installed wrong.
Discharge window wrong or not set
In Timed Discharge mode, the battery only discharges during the configured window. If the window is not set, is set to the wrong times, or is running on the wrong clock timezone, the battery will sit idle during the intended discharge period.
Grid overvoltage protection
When grid voltage exceeds the inverter’s safety threshold, the inverter suspends discharge as a protection measure. Most common on summer afternoons. Check the event log for overvoltage entries.
BMS or hardware fault
Less common. A BMS protection event — due to cell imbalance, over-temperature, or voltage deviation — can lock the battery out of discharge. Usually shows as a fault code in the event log. Requires engineer involvement.
Step-by-step diagnostic
Work through these in order — most cases are resolved before step 4.
1
Check system mode and discharge configuration
Open your portal or app and find the system mode setting. Eco Mode and Self-Consumption mode are reactive — they discharge only when house demand exceeds solar output. They will not proactively discharge the battery overnight to cover home loads.
If you want the battery to discharge on a schedule — for example during 4pm–8pm peak-rate electricity — you need Timed Discharge or Time of Use mode. Set the mode, configure the discharge window and target SoC, save, and verify the setting has stuck.
2
Check the minimum SoC reserve
Find the operating range or minimum SoC setting in your portal. Check what the floor is — if it is set to 20% and the battery is currently at 21%, it will not discharge any further. Note the current battery SoC and compare it to the minimum. If they are close, the battery is working correctly — it has just reached its configured floor. Lower the minimum SoC if you want to access more of the stored energy.
3
Check the discharge window times
If you are using Timed Discharge or Time of Use mode, confirm the discharge window matches your intended period. Also check the inverter clock — if it is running on UTC when the UK is on BST (UTC+1), the window runs one hour out of phase.
Example: if you want the battery to discharge 16:00–20:00 and the inverter is on UTC during BST, you need to set the window to 15:00–19:00 — or switch the inverter clock to local time.
4
Run the CT clamp live load test
Turn on a kettle and watch the grid import or house load reading in your portal. It should rise by approximately 2,000–3,000W. If the reading falls, stays flat, or moves in the wrong direction, the CT clamp is reversed — the inverter cannot correctly read house demand, so it cannot direct the battery to cover it. See the CT clamp installed wrong guide for the full diagnostic.
5
Check the event log for overvoltage and fault codes
Open the event log in your portal and look for grid overvoltage events, battery protection trips, BMS warnings, or cell voltage alarms. Grid overvoltage (typically above 253V) causes the inverter to suspend discharge automatically. BMS protection events indicate a battery-side hardware issue. Either way, note the exact fault codes — they are the most useful information for a remote diagnostic session.
Battery discharging but not powering the home
If your portal shows the battery discharging but the home is still drawing from the grid — or your export figure rises when the battery discharges — the discharge energy is going the wrong way. This is almost always a CT clamp or metering issue.
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CT clamp reversed — discharge appears as grid export. A backwards CT clamp inverts the grid measurement. When the battery discharges, the inverter reads it as energy flowing to the grid rather than to the home — so it appears to export rather than consume. The home continues drawing from the grid as normal. The CT clamp test above will confirm this.
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Export limit set to 0W blocking discharge. On some systems, a 0W export limit can cause the inverter to restrict or curtail discharge if the CT clamp reading suggests export is occurring. Check the export limit setting in your configuration — if it is 0W and the CT is misreading, discharge may be suppressed. See CT clamp installed wrong for the fix.
▸
Grid overvoltage causing intermittent discharge suspension. If the battery discharges inconsistently — powering the home sometimes but not others — check the event log for intermittent overvoltage events. Grid voltage spikes cause temporary discharge lockouts that can look like the battery is failing to discharge when it is actually responding to a grid protection trigger.
The most common causes are: system mode is set to Eco Mode which only discharges reactively to cover demand, not proactively at a set time; the minimum SoC reserve is set too high so the battery stops discharging too early; the discharge window is not configured correctly; or the CT clamp is reversed so the inverter cannot read house demand. Check in this order.
If the battery shows charge but the home is drawing from the grid, the most likely causes are: the system mode is not configured to discharge at that time of day; the CT clamp is reversed so the inverter cannot direct the discharge correctly; or the minimum SoC has been reached. A reversed CT clamp is particularly common and causes discharge energy to appear to flow to the grid rather than the home.
The minimum SoC reserve is the lowest level to which the battery will discharge — typically set to 10–20% to protect cell longevity. You can find and adjust it in the operating range or system mode settings in your inverter app or portal. Reduce it carefully — discharging below 5–10% consistently will accelerate battery degradation over time.
The battery has a minimum SoC reserve set to 20% — either configured by your installer to protect battery longevity, or set as a manufacturer default. The battery is functioning correctly. If you want to use more of the stored capacity, lower the minimum SoC setting in your system mode or operating range configuration. Be aware this increases cycle depth and may affect long-term battery health.
Yes. When grid voltage rises above the inverter’s safety limit — typically 253V — the inverter suspends discharge as a protection measure. This is most common during sunny afternoons in summer when local grid voltage is elevated by other solar exports nearby. Check the event log for overvoltage or grid fault entries. Persistent events should be reported to your DNO.
If the portal shows the battery discharging but the home is still importing from the grid, the most likely cause is a reversed CT clamp. The discharge energy is being measured incorrectly — appearing to flow to the grid rather than the house. Run the live load test: turn on a kettle and watch the grid import figure. If it moves in the wrong direction, the CT clamp is the cause.
Still not discharging after working through this?
A remote diagnostic session includes a live review of your portal data — system mode, discharge history, CT clamp readings, and event log. We confirm the exact cause and tell you whether it is a settings fix or whether an engineer needs to attend.
