Micro Inverter vs String Inverter: The 2026 UK Verdict
A string inverter is one central box converting DC from a whole string of panels to AC. Microinverters sit on each panel, converting at the panel. The practical difference: with a string inverter, one shaded panel drags the string down; with per-panel electronics, each panel performs independently. Clean unshaded roof → string inverter (Spectrum default: Solis hybrid — cheaper, simpler, integrates battery in one box). Shaded or complex roof → per-panel electronics — we fit SolarEdge with DC optimisers. The roof decides, not a blanket rule.
There's a third option most guides skip
The "micro vs string" framing misses the option Spectrum actually uses most for difficult roofs: a string inverter with DC optimisers (SolarEdge). It gives you per-panel optimisation like microinverters, but keeps a central inverter that's far easier to pair with battery storage. For UK homes wanting both shade tolerance AND a battery, this is usually the sweet spot — we cover all three topologies below.
In This Guide
What does a solar inverter actually do?
Solar panels produce DC (direct current) electricity. Your home and the grid run on AC (alternating current). The inverter converts DC to AC. It's the brain of the system — it also handles maximum power point tracking (squeezing the most from the panels), grid synchronisation, safety isolation, and (on hybrid models) battery charge/discharge control.
String inverters
A string inverter connects to a "string" of panels wired in series. One central unit (mounted in the loft, garage or utility room) handles the whole array. This is the most common topology in the UK and Spectrum's default for standard installs — specifically the Solis hybrid, which handles solar and battery in one box.
String inverter strengths
- Lower cost — one unit for the whole array
- Simple, proven, easy to service
- Hybrid models integrate battery seamlessly
- One point to monitor and maintain
- Ideal for clean, single-orientation roofs
String inverter weaknesses
- One shaded/weak panel drags down the whole string
- Less ideal for multi-orientation roofs
- Single point of failure (one inverter, whole system down)
- No panel-level monitoring without add-ons
Microinverters
Microinverters are small units fitted to each individual panel, converting DC to AC at the panel itself. Enphase is the dominant brand. Each panel operates independently — shade on one doesn't affect the others.
Microinverter strengths
- Each panel operates independently — shade-tolerant
- Per-panel monitoring built in
- No single point of total failure
- Good for complex/multi-orientation roofs
- Easy to expand the array later
Microinverter weaknesses
- 20–40% higher cost than string
- Many units on the roof = more potential failure points
- Harder/costlier to service (units are up on the roof)
- Battery integration is more complex — AC-coupled only
- Less elegant for whole-home energy management
Key differences at a glance
| Factor | String inverter (Solis) | String + DC optimisers (SolarEdge) | Microinverters (Enphase) |
|---|---|---|---|
| Cost | Lowest | Medium | Highest |
| Shade tolerance | Low | High | High |
| Per-panel monitoring | No (add-on) | Yes | Yes |
| Battery integration | Excellent (hybrid, DC-coupled) | Good (Energy Bank) | Complex (AC-coupled) |
| Failure points | One (central) | One inverter + optimisers | Many (one per panel) |
| Servicing | Easy (ground-level unit) | Easy (central inverter) | Harder (roof-level units) |
| Best for | Clean single-orientation roof | Shaded / complex roof + battery | Shaded roof, no battery priority |
| Spectrum fits? | YES (default) | YES (shaded/complex) | On request |
Which is best for your roof?
1 Clean, unshaded, single-orientation roof
String inverter (Solis hybrid). You won't see any benefit from per-panel electronics, and you'll pay 20–40% more for nothing. The hybrid integrates your battery in one box. This covers the majority of UK domestic installs.
2 Shaded roof (chimney, trees, dormers)
SolarEdge with DC optimisers. Each panel performs independently, so shade on one doesn't drag down the rest — but you keep a central inverter for easy battery integration and servicing.
3 Multiple orientations (E/W split, multi-pitch)
SolarEdge optimisers or microinverters. Panels facing different directions peak at different times; per-panel electronics let each contribute its maximum.
4 Complex roof, no battery wanted
Microinverters (Enphase) are a clean fit — though even here, SolarEdge often wins on whole-system manageability if you might add a battery later.
Cost and ROI
| Topology | Relative cost (5kWp) | When ROI works |
|---|---|---|
| Solis string hybrid | Baseline | Clean roof — always best value |
| SolarEdge + optimisers | +£800–£1,500 | Shaded/complex roof — gain > cost |
| Enphase microinverters | +£1,200–£2,200 | Shaded roof, no battery, expansion likely |
Don't pay for shade tolerance you don't need
The biggest mistake we see is homeowners paying a premium for microinverters on a clean south-facing roof because a sales rep told them they're "better." On an unshaded roof, a Solis string hybrid produces the same energy for less money — and integrates a battery far more cleanly. The right answer is roof-specific.
Why the inverter choice matters
The inverter is the single most important component decision after the panels themselves. It determines:
- Shade behaviour — how much one underperforming panel costs you
- Battery options — DC-coupled hybrid vs AC-coupled retrofit
- Monitoring granularity — system-level vs per-panel data
- Automation potential — Solis hybrid + Predbat is our Octopus Agile optimisation stack
- Serviceability — ground-level central unit vs roof-level micro units
Professional guidance — we assess the roof first
Spectrum doesn't pick an inverter topology from a price list — we assess your roof's shading, orientation and complexity at the site survey, model it in PV*SOL, and recommend the topology that delivers the best generation-per-pound for your roof. For most clean UK roofs that's a Solis hybrid; for shaded or complex roofs it's SolarEdge with optimisers.
Not sure which inverter your roof needs?
We assess shading and orientation at the site survey and model it in PV*SOL before recommending. Solis hybrid for clean roofs, SolarEdge optimisers for complex ones. No upsell to electronics you don't need.
Request a feasibility assessmentFAQs
What's the difference between a micro inverter and a string inverter?
A string inverter is one central unit that converts the DC from a whole string of panels into AC for your home. Microinverters are small units fitted to each individual panel, converting DC to AC at the panel itself. The key practical difference: with a string inverter, one shaded or underperforming panel drags down the whole string; with microinverters (or DC optimisers), each panel performs independently. String inverters are cheaper and simpler; per-panel electronics handle shading and complex roofs better.
Which is better for a UK home?
For a clean, unshaded, single-orientation roof: a string inverter (Spectrum default: Solis hybrid) is the better value — simpler, cheaper, and a hybrid handles battery and solar in one box. For a shaded roof, multiple orientations, or a complex roof shape: per-panel electronics win, and we fit SolarEdge with DC optimisers. The roof decides, not a blanket rule.
Does Spectrum fit microinverters?
We primarily fit Solis hybrid string inverters (our default) and SolarEdge with DC optimisers for shaded/complex roofs. Both give per-panel benefits where needed. We can fit microinverters (Enphase) on request, but for most UK domestic installs a Solis hybrid or SolarEdge optimiser system delivers the same shade-tolerance with simpler battery integration. Microinverters complicate adding battery storage.
Are microinverters worth the extra cost?
On a shaded or multi-orientation roof, yes — the generation gain from independent panel operation outweighs the cost premium. On a clean south-facing roof, no — you're paying 20–40% more inverter cost for a benefit you won't see. The honest answer depends entirely on your roof, which is why we assess shading and orientation at the site survey before recommending an inverter topology.
Related reading
- New solar panel technology trends 2026
- How to choose the right solar battery
- Home Assistant for solar PV
- How efficient are solar panels in 2026?
- Problems with solar panels
Speak to Spectrum Energy Systems
MCS NIC200223. Solis hybrid and SolarEdge optimiser systems installed across the East Midlands. We pick the topology your roof needs.
Request a feasibility assessment