Massively massively recommended. We had a big battery array (49kW across three phases) put in four years ago. c £35k cost. It’s been a total nightmare for many reasons, not least 1. our installer being totally useless and unresponsive and 2. Givenergy, our battery supplier, going bust. Long story short it had never worked anywhere near properly despite countless hours on phones and emails; the best we’d achieved was one third of the batteries working. Rather than write it off, I asked a PM friend to try to source someone who could come on site and review and revive the system. He found Solar Tech Support and Ron. Ron assured us he was the man to get it going again. After so many years of pain, I was not convinced but, true to his word, five hours later it was up and running. Lovely chap, super knowledgeable with a support team to lean on who are also clearly super technical. I honestly didn’t think there was much chance of getting this array going ever again so was absolutely delighted when Ron and team pulled it off. Bravo!
Solar system underperforming
- PVGIS gives the honest benchmark
- String faults are diagnosable remotely
- New shading is a common hidden cause
A solar system health check includes a full generation audit, string performance analysis, and a written report identifying the cause and quantifying the generation loss.
Book a Health CheckFree remote diagnosticThis company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing. If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.
Solar Tech Support is an absolute lifesaver. My solar and battery system stopped working completely, but after one quick phone call, they fixed the problem straight away. The original provider, GivEnergy, has gone into administration, leaving me entirely without support from the original installers. It was a terrible situation on GivEnergy’s part, but thankfully, Solar Tech Support came to the rescue!
Big thanks to Ron. He was incredibly patient and helpful over the phone, taking the time to walk myself and the installer through every troubleshooting step. Through lots of testing he figured out the issue was definitely a hardware issue, which allows us to consider our next steps. Support fees are clear and they operate a “no fix no fee” policy. It is rare to find that kind of honesty combined with dedicated phone support nowadays. I highly recommend Ron, if you need help with your solar system don’t hesitate to give him a call.
When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.
Absolutely amazing service. Ive had a couple of issues with my Givenergy system and couldn't manage to get in touch with Givenergy after they went bust. So I was searching on Google and came across Rons number. I sent Ron a WhatsApp message and got a prompt reply and he resolved the problem I had with my system. I can't recommend Ron enough its not often you get such a good service in this day and age. If you are experiencing issues with your solar system Ron is the man to contact.
Step 1 — Establish a realistic expected output
Installer projections are often optimistic. The honest benchmark is PVGIS — a tool from the EU Joint Research Centre that calculates expected solar yield for any location in Europe using decades of irradiance data.
Go to pvgis.ec.europa.eu, enter your postcode, set your panel rated power (in kWp), orientation (azimuth — 0° is south), and tilt angle. The tool gives you an annual kWh estimate that accounts for your specific location and mounting.
As a rough guide, UK systems produce approximately:
A system generating 80–100% of its PVGIS estimate is performing well. Below 75% warrants investigation.
Common causes of genuine underperformance
If the system is confirmed below 75–80% of PVGIS, check these.
Trees that have grown, a new extension, a neighbouring building, or a satellite dish. Even a small shadow on a single panel in a string system can halve that string's output through the "Christmas lights effect".
One inverter MPPT channel or string has failed — from a blown fuse, open-circuit cable, or inverter fault. On a two-string system this typically reduces generation by around 50%.
Individual panel failure (from hotspot damage, delamination, or PID degradation) reducing output below the expected rate. More common on systems over 8 years old.
A DNO export limit is actively curtailing generation on sunny low-load days. The system isn't underperforming — it is deliberately limited. Check whether the generation figure hits a ceiling on sunny days.
An ageing inverter operating below its rated efficiency. More common on string inverters over 10 years old where capacitors and switching components have degraded.
Heavy panel contamination from bird droppings, dust from construction, or a nearby industrial source. Rarely the primary cause in the UK — but worth checking visually if significant soiling is visible from the ground.
How to identify the cause
Using monitoring data to narrow it down.
Run your system through PVGIS and compare the estimate against your last 12 months of generation data from the portal. If the shortfall is above 20%, the investigation is worthwhile. If it is within 15–20%, check whether the PVGIS inputs accurately reflect your actual orientation and shading.
In the monitoring portal, check whether your inverter shows separate data for each string or MPPT channel. On a sunny day both strings should show similar current levels. If one string shows near-zero current while the other is normal, you have a string fault — blown fuse, open circuit cable, or disconnected panel.
On the sunniest days in summer, does the generation figure plateau at a specific number — say 3.0kW on a 5kWp system — rather than climbing towards peak rated output? If yes, check whether an export limit is set at that figure in your inverter configuration.
Go outside at solar noon (midday in winter, 1–2pm BST in summer) and look at the panels from the ground. Check whether any trees, structures, or objects are now casting shadows onto the array. Even a shadow on one panel can drag down an entire string.
If the monitoring portal shows multiple years of history, compare annual totals year-on-year. A gradual decline of 0.5–1% per year is normal degradation. A drop of 5% or more in a single year indicates a fault event — check the event log for that year for fault codes or equipment changes.
Brand-specific underperformance checks
Each monitoring platform exposes generation data differently. Use the note for your brand to find the right figures for your PVGIS comparison.
GivEnergy portals show daily PV generation on the Generation page. Compare the daily kWh figure against your PVGIS estimate for the same calendar month. Note that some older firmware versions report generation from the CT clamp rather than the PV input — if your daily figures fluctuate wildly with load, check which measurement source is configured. See the GivEnergy hub for portal navigation help.
Growatt's ShineServer portal provides per-MPPT yield data for multi-string hybrid systems. Navigate to Device > Details to compare MPPT1 and MPPT2 daily yield — a significant divergence between strings isolates the underperformance to one set of panels or one MPPT channel, making diagnosis much faster.
Use the Sunsynk Connect app History view to compare daily yield across recent weeks. If a single week shows a step-change drop with no weather explanation, correlate with the inverter event log for that date — a firmware update or grid event on that day often explains the change. Sunsynk inverters can also experience MPPT derating in partial shade conditions; a soft reset of MPPT tracking can help.
Frequently asked questions
Confirmed underperformance — get it investigated
A solar system health check includes a full generation audit against PVGIS, string-level performance analysis, and a written report identifying causes and quantifying the generation loss in kWh and £ per year.
- Independent — not affiliated with any manufacturer
- Health check from £145
- PVGIS audit + written report included
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