Daily operating pattern · solar and grid charging
Solar cycleOne full cycle · 26p/kWh£26.00/day
Overnight grid charge03:00 charge · 07:00 discharge4p/kWh saving · £2.40/day
Total daily energy delivered100 kWh solar + 60 kWh grid£28.40/day gross benefit
The daily pattern described by the site includes a separate 60 kWh morning discharge after overnight grid charging, plus a full 100 kWh solar cycle. These figures illustrate that pattern; they are not the measured 17–22 September totals shown below. Rings are visual labels, not live state-of-charge readings.
Rob Mutimer · Woodlands Farm
“It earns its keep whether the sun’s shining or not.”
The battery has worked really well for us. We originally started looking at it because we wanted to get more from the solar we already had, but it’s actually doing more than that now. HIT manage when we’re charging and using the battery, including charging from the grid when electricity is cheaper, so it earns its keep whether the sun’s shining or not. We’re a busy farm and the business is always changing. We’ve got delivery vans, we’re looking at electric vehicles and we’d already been thinking about adding more solar. What I like is that we’ve now got something we can build on rather than having to start again every time the farm needs more power. It’s been pretty much a case of letting HIT get on with managing it for us, which is exactly what I wanted.
— Rob Mutimer, Woodlands Farm
Cheaper overnight electricity. Stored solar for later.
The farm’s butchery starts work early, before solar production reaches its daytime peak. HIT Energy Guard starts grid charging at 03:00, taking the battery to 60% (60 kWh). Discharge begins at 07:00, when the cheaper electricity rate finishes, and the farm’s morning demand uses that charge completely each day. This saves 4p per kWh through tariff shifting. The battery then charges from surplus solar and delivers a separate full 100 kWh cycle for use on site, avoiding daytime electricity at 26p per kWh. The stated daily pattern therefore delivers 160 kWh across the morning tariff-shifting discharge and the full solar cycle.
Illustrative annual benefit · 312 operating days
£8,860.80 gross annual benefit
Solar contribution: one full 100 kWh cycle each day × £0.26/kWh = £26.00 per day, or £8,112.00 over 312 operating days.
Overnight tariff shifting: 60 kWh/day × £0.04/kWh tariff difference = £2.40 per day, or £748.80 over 312 operating days. Total illustrative gross benefit: £28.40 per operating day.
This is an operating scenario, not measured annual savings or a forecast from the six-day dataset below. It assumes those daily energy amounts can be delivered on each operating day. The solar contribution is before any lost export income; battery losses, operating costs and seasonal variation are excluded. Actual net savings depend on the site’s tariffs, export payment arrangement and measured operation.
Executive view
One near-full cycle a day. Surplus still leaves the site.
Across 17–22 September 2026, the battery charged an average of 92.8 kWh and discharged 97.5 kWh per day. The two strongest export days totalled 477 kWh. That makes further storage worth modelling—not a foregone conclusion.
Data position
These figures use six complete continuous days. The connection began on 9 September; 9 and 23 September are partial days, and 10–16 September contain zero readings in the dataset. That gap is not evidence of zero site activity. PV generation is not separately metered, so gross demand, direct solar use and verified savings remain unconfirmed.
Dated daily performance
Six complete days, not an annual forecast
17–22 September 2026 · Battery charge, discharge and grid export in kWh.
Daily values are rounded. The six-day headline totals come from the platform’s aggregated readings.
Woodlands Farm is a good example of how an established solar asset can be developed without unnecessarily replacing what is already working. The farm has an existing 100 kWp ground-mounted solar PV system operating under the Feed-in Tariff (FIT), which HIT Energy Services has monitored for approximately five to six years.
Over that period, HIT has supported the original solar with inspections, fault investigations and targeted repairs. The dated records below show how that maintenance work provides the foundation for the farm’s storage and future expansion.
PV maintenance history · 2022–2026
Years of care before the battery arrived
The battery project builds on a documented history of inspection, fault finding and targeted repairs to the existing solar asset. A snapshot from HIT’s site reports:
- 2022 — Establish the condition and restore visibility. April’s health check covered the inverters, modules, AC equipment, fuses and DC strings. It identified an internal inverter fault, low insulation readings and connector deterioration. May and June visits restored remote access and inverter reporting; October testing investigated insulation alarms across three inverters.
- February 2023 — Repair a water-ingress fault. Engineers found and replaced a loose MC4 connector. The affected string’s insulation resistance improved on retest, and all inverters were producing and reporting when the team left.
- October 2023 — Inspect, test and keep monitoring connected. The health check recorded the installation in good condition, with DC testing, fuse and connection checks. A separate visit restored reporting with a replacement SIM and a data-logger firmware update.
- 2025 — Check performance and identify the next repair. March’s inspection found good test results and recommended panel cleaning. July and October investigations identified an E031 internal inverter fault requiring replacement.
- January 2026 — Replace the faulty inverter. A new Solis inverter was installed and generation restored. Communication cabling was terminated and joined for integration with the existing monitoring system.
- April 2026 — Replace damaged panels and improve communications. Damaged modules were replaced, the remaining panels inspected and insulation testing carried out. A weatherproof junction box and glands were fitted to the inverter communication cable; the report also identified a lower-reading string for ongoing monitoring.
Inspect. Repair. Monitor. Then build on what works.
Source: HIT Energy Services inspection and repair records dated April, May, June and October 2022; February and October 2023; March, July and October 2025; January and April 2026. This is a selected history of recorded work.
The starting point: keep the original FIT system producing
Because the existing solar is productive, there is no reason to repower it simply because of its age. HIT’s approach is to use monitoring and engineering evidence to determine what the asset actually needs.
HIT Energy Guard looks beyond a basic generation figure. Depending on the system configuration, we monitor individual DC strings, voltage and current, together with AC parameters such as frequency and wider system performance. Data is captured at 10-minute intervals, and on some HIT-supported sites this operational history now extends to around 15 years.
Monitoring tells us whether a system needs cleaning, maintenance, fault finding, inverter replacement or targeted repowering – and, just as importantly, when it does not.
Capturing available surplus solar
The next opportunity on this site was not replacing the existing array, but making better use of the electricity it already generates.
A 100 kWh battery storage system has been installed alongside the existing FIT solar. When solar production exceeds the farm’s immediate demand and the site begins exporting, the battery controls can detect that export and capture available surplus generation, subject to battery state of charge, system power limits and operating conditions.
That stored renewable energy can then be used later on site, allowing the farm to retain more value from the solar electricity it is already producing. The original solar keeps generating, the FIT arrangement stays intact and the battery makes better use of energy that would otherwise be exported.
What the first operating data shows
HIT Energy Guard recorded the first complete continuous comparison period from 17–22 September 2026. Across those six full days, the battery recorded:
- 557 kWh charged – an average of 92.8 kWh per day.
- 585 kWh discharged – an average of 97.5 kWh per day.
- 750 kWh exported to the grid, even while the battery was operating.
- Peak export of 265 kWh on 20 September and 212 kWh on 21 September.
The results show regular battery use at close to one full equivalent cycle per day. They also show that substantial solar surplus can remain after the existing battery has charged. The 477 kWh exported across the two strongest solar days supports progressing detailed modelling for a further 100 kWh of storage, subject to half-hourly export duration, later site demand, charge-power headroom and state-of-charge data.
Important data note: the existing PV generation is not separately metered, so gross site demand, total self-consumption, battery efficiency and verified financial savings cannot yet be calculated from this short dataset. Charge and discharge totals also reflect the battery’s state of charge at the beginning and end of the selected period. HIT will continue monitoring before any expansion or savings figure is confirmed.
Project update · September 2026
Install. Monitor. Install again.
The first 100 kWh battery has been operating while HIT monitors charging, discharge and remaining export. On the strength of that review and the site’s plans to electrify its delivery fleet, the customer has now ordered a further 100 kWh battery bank.
Installed now
Ordered next
Planned total
Capacity comparison only. The 17–22 September operating data above belongs to the first 100 kWh bank. How much of the remaining export a second bank can capture depends on charging power, when export occurs and later site demand.
The additional bank is ordered, not yet installed or included in the measured figures above. Its performance and any savings will be assessed after commissioning.
A battery installation designed for the farm’s future
This is a farm-to-fork business with a significant delivery operation. Rob is looking towards changing more of the farm’s delivery vans to electric vehicles, which is expected to increase future electrical demand.
The HIT Energy Services True Charge storage solution therefore provides more than battery capacity for today’s surplus generation. Its hybrid inverter architecture gives the farm a route to add further solar PV in the future as demand grows.
Additional PV modules, mounting, cabling and installation would still form part of any future expansion, but the hybrid inverter capability is already within the battery solution. This means additional PV can be connected through the hybrid platform without purchasing another dedicated solar inverter for that expansion.
Expandable on demand
The result is a scalable energy strategy: keep the original FIT asset performing, capture available excess generation today, and create the infrastructure to support additional solar and electric vehicles as the farm’s demand develops.
From solar monitoring to intelligent energy management
For suitable sites, HIT Energy Guard can bring together detailed PV performance, battery operation, site demand, electricity tariffs and weather forecasting. Intelligent battery management can then help determine when energy should be charged, held or discharged, with the aim of increasing self-consumption and reducing avoidable grid costs.
What this project demonstrates
- The original 100 kWp FIT solar remains productive and is retained rather than unnecessarily repowered.
- HIT has monitored the system for around five to six years and used that knowledge to support targeted maintenance and inverter changes.
- The 100 kWh battery is cycling regularly and capturing available surplus generation.
- Significant export remains on the strongest solar days, supporting the decision to order another 100 kWh bank, with its operation still to be measured.
- The battery installation creates a platform for the farm’s planned move towards electric delivery vehicles.
- The hybrid inverter architecture allows additional PV to be added later as demand increases.
- Monitoring and engineering evidence drive the investment decision rather than the age of the solar system alone.
Monitor. Understand. Protect what works. Capture the excess. Expand when needed.
Frequently Asked Questions – Legacy FIT Solar & Battery Storage
Can battery storage be added to an existing FIT solar PV system?
Yes. Battery storage can be added alongside an existing FIT solar PV installation without having to replace or significantly alter a solar system that is already performing well.
At HIT Energy Services, our approach is to understand what you’ve already got before telling you what you need. If the existing FIT solar is generating well, we’ll leave it doing exactly that and design the battery storage around the existing asset.
Will adding battery storage affect my Feed-in Tariff (FIT) payments?
No. In the type of retrofit system HIT typically installs, the battery storage is kept separate from the existing FIT solar PV system, so the original FIT installation and generation metering remain unchanged.
The battery system is normally connected on the incoming electrical supply and monitors the site’s power flow. When surplus solar generation is detected exporting from the site, the battery responds by charging and capturing that available energy rather than allowing it to leave the site.
This means the existing FIT solar installation can continue operating and receiving its FIT generation payments as before, while the site gains the additional benefit of storing surplus electricity for use later.
The original solar keeps generating. The FIT arrangement stays intact. The battery simply makes better use of the energy that would otherwise be exported.
Should I repower an older solar PV system before installing battery storage?
Not necessarily. The age of a solar PV system alone isn’t a reason to repower it.
We first look at how the existing system is actually performing. Using HIT Energy Guard, together with our engineering inspections and historical performance data, we can establish whether the system is generating as it should.
If it’s performing well, we’ll tell you. Leave it alone and let it generate.
If there are problems, we’ll establish whether maintenance, repairs or selective repowering would provide the best solution before recommending unnecessary replacement.
What happens to surplus solar once a battery is installed?
The battery system monitors the site’s import and export.
When the solar PV is producing more electricity than the site is consuming, the battery can detect that surplus generation and begin charging. Instead of immediately exporting that available electricity, it can be stored for use later when site demand increases or solar generation falls.
This allows a business to make better use of the electricity its existing solar asset is already producing.
Can additional solar PV be added in the future?
Yes. One of the advantages of designing the battery system correctly from the beginning is that future energy requirements can be considered as part of the installation.
For this project, the hybrid battery system provides the opportunity to add additional solar PV in the future as the farm’s electricity demand increases.
This is particularly relevant as the business considers moving its delivery vehicles towards electric, potentially creating significant additional daytime and overnight electricity demand.
How does HIT Energy Guard manage solar PV and battery storage?
HIT Energy Guard was originally developed by HIT Energy Services more than a decade ago to independently monitor commercial solar PV systems.
We’re now using that experience, together with years of historical solar generation data, to help manage battery storage.
For compatible systems, HIT Energy Guard can bring together live solar generation, site electricity demand, historical performance, weather forecasts and electricity tariffs. Intelligent management can then help determine whether the battery should:
CHARGE – HOLD – DISCHARGE
Rather than the battery simply reacting to what’s happening at that moment, the aim is to make more informed decisions about how the site’s energy should be stored and used.
Is HIT Energy Guard battery management an additional subscription?
Where compatible battery storage is integrated with HIT Energy Guard, our intelligent battery management is included within the usual HIT Energy Guard monthly subscription.
This means the same platform that helps us understand how the solar PV is performing can also help manage how the site’s stored energy is used.
One platform. One monthly subscription. Solar monitoring and intelligent battery management working together.
