Beyond the Datasheet: Engineering a Solar and Battery Retrofit in Narok

When the mounting table changes the string design

The existing array consisted of 48 panels arranged into three strings of 16. The expansion was intended to add another 64 panels on a separate mounting table, but the new table could accommodate only 60.

We revised the new array to four strings of 15 panels, retaining the existing three strings of 16.

The lesson was simple: mounting capacity and electrical string design must be coordinated. A change in the number of panels a structure can accommodate requires a review of the electrical arrangement.

Resolving battery communication

The existing master inverter communicated with its batteries, while the newly installed slave inverter reported F58—battery communication loss. The battery modules appeared to communicate internally without alarms, but communication with the inverter remained unsuccessful.

We checked the communication wiring and settings repeatedly. Deye’s technical team also updated both inverters to matching firmware versions, but the issue persisted.

Further work with CFE identified an additional configuration requirement affecting the V2 batteries in high-voltage operation. Under CFE’s guidance, settings were adjusted through a software configuration tool, restoring communication with the inverters.

According to the guidance received, this adjustment had not been necessary with the older BMS version. The exact parameter is not documented here, so the resolution is specific to this installation.

The experience reinforced an important distinction: successful communication between battery modules does not, by itself, confirm communication between the complete cluster and the inverter.

Building compatible battery clusters

The installation included nine older-version batteries and fifteen V2 batteries. The V2 nameplate identified the model as CS-10H, rated at 10.24 kWh, 51.2 V and 200 Ah.

To achieve four compatible six-module clusters, three V2 batteries were fitted with older-version BMS hardware under CFE’s guidance.

The final arrangement comprised:

• One cluster of six original older-version batteries.

• One cluster of three original older-version batteries and three V2 modules fitted with older-version BMS hardware.

• Two clusters of six V2 batteries each.

This retained the intended four-cluster arrangement. The BMS changes were manufacturer-guided work specific to the equipment involved.

Matching battery states of charge

The modules also had different states of charge.

We formed temporary clusters of three or four batteries with closely matched SOC values and charged selected groups from PV in high-voltage mode. Modules with substantially different SOC values were charged separately from mains using a Victron inverter in an open-loop 48 V configuration, also under CFE’s guidance.

The purpose was to match the modules’ states of charge before assembling the final clusters. This was SOC matching between battery modules, a separate task from balancing individual cells inside a battery.

The process added commissioning time but gave the final clusters a more consistent starting point.

Why containment specifications matter

We had requested trunking with a depth of 100 mm, but 50 mm-deep trunking was supplied. With two inverters, four battery clusters and the associated AC and DC wiring, the shallower containment created congestion and restricted cable routing.

For this arrangement, our recommendation was approximately 200 mm wide by 100 mm deep, subject to checks against the actual cables, bend radii, gland dimensions and equipment-entry clearances.

We spaced equipment away from the main trunking where necessary and installed short perpendicular connecting sections. An additional parallel trunking run accommodated the DC battery cables, creating more room in the main route.

At sharp routing points, protective sleeving was added to reduce abrasion risk, alongside attention to cable bend radii.

The cables were reorganised to reduce mechanical strain and improve routing within the containment. These site adaptations reinforced the importance of providing adequate space for cable installation and equipment connections from the outset.

Adequately sized trunking should be provided from the outset. Its dimensions need to remain part of the technical specification throughout procurement.

Providing suitable breaker enclosures

The DC MCCBs were supplied without enclosures, so suitable boxes had to be ordered separately.

We selected lockable enclosures with hinged doors for easier operation and maintenance, then labelled them to identify the circuits they served.

Enclosure selection needs to account for access, cable entry, identification, and protection against contact with live parts. It belongs in the procurement specification alongside the breaker.

What this retrofit taught us

The Narok project demonstrated how much successful integration depends on details beyond equipment ratings.

BMS generations affected cluster composition. Software configuration affected inverter communication. Different SOC values required additional commissioning work. Mounting space changed the string arrangement, while undersized trunking required additional containment and rerouting.

At Buddy Systems, these experiences inform how we survey, specify, install and commission subsequent projects. Clear procurement specifications, checks on equipment revisions and adequate cable-routing space help reduce avoidable work on site.

With battery communication restored, module states of charge matched and the intended four-cluster arrangement achieved, the expanded system was brought into operation. The work behind that outcome shows why reliable solar installations depend on the engineering that connects every component into a functioning system.