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Technical solutions · Bilotex
A single shadow steals up to 30% of your production
On an unoptimized system the most shaded cell limits the WHOLE string. We explain which technology to use depending on your inverter — Huawei, SolarEdge or Tigo (for Growatt and Deye) — and why.
The problem: string effect
On a conventional string inverter, panels are wired in series. If ONE gets shaded, soiled, or differs in output — it limits all the others.
Modern panels (550-590 W) deliver ~10 A at MPP. If a tree branch falls on one panel, the whole string current drops to the shaded panel's level: the others keep 'pulling voltage', but useful power drops proportionally.
On small or complex roofs (chimneys, windows, neighbour houses) this effect is the main reason PVGIS simulations overestimate your real production by 15-30%.
The solution is to decouple each panel — let each module work at its own MPP. That's exactly what a power optimizer does.
3 technologies · 3 philosophies
All solve the problem, but each is best paired with a specific inverter family. This is the choice our calculator makes internally:
Huawei SUN2000-P
For Huawei SUN2000 inverters
~€80/panel
- Optimizers designed to pair with SUN2000 over a proprietary bus
- Zero configuration — the inverter detects them automatically
- Built-in NEC 690.12 rapid shutdown
- 25-year warranty (same as the panel)
- Only compatible with Huawei inverters
SolarEdge S-Series
For SolarEdge HD-Wave inverters
~€70/panel
- The inventor of module-level optimization (2009)
- Operates at fixed voltage (350-400 V) — strings of any length
- Per-panel monitoring in the SolarEdge app
- Built-in SafeDC rapid shutdown
- MANDATORY on SolarEdge systems — not optional
Tigo TS4-A-O
For Growatt, Fronius and as a Deye fallback (any string inverter)
~€62/panel
- Compatible with ANY string inverter on the market
- Up to 700 W per panel — fits modern 550-590 W modules
- Install only on panels that need optimization (selective)
- Needs CCA + TAP gateway (€250 extra, once per system)
- Best option if you already own a Growatt or Deye inverter
Which to pick based on your inverter?
Simple rule — and the exact one our calculator uses:
When does it really pay off?
Partial shade
Chimneys, antennas, trees, neighbour houses — anything that shades 1 or 2 panels at certain hours.
Mixed-orientation roofs
If you spread panels over two orientations (East/West), one string suffers — optimizers eliminate it.
Mandatory rapid shutdown
New Spanish installs (RD 244/2019, NEC 690.12) require rapid shutdown — optimizers handle this automatically.
Dust and soiling
Coastal or dusty regions (Almería, Murcia) soil panels unevenly. Optimizing prevents one dirty panel from throttling the entire string.
Frequently asked questions
Do I need an optimizer on EVERY panel?+
With Tigo and Huawei, no — only on shaded panels (selective). With SolarEdge yes, mandatory on all panels. Our calculator always quotes 1 per panel to keep warranty and full monitoring.
How much does it cost to add optimizers to a 6 kW system?+
Roughly: 12 panels × ~€62 (Tigo) ≈ €750 + €250 CCA gateway. About €1 000 extra. Payback is 2-3 years thanks to the extra production you recover.
Can Tigo be added to an already-installed system?+
Yes, it's retrofittable. It connects to the panel junction boxes without touching the inverter — that's why it's the favourite in retrofits of older systems.
What if I buy a Deye without optimizers and shade appears later?+
You can add Tigo later. But if you already know you'll have shade, integrating from day one saves 1-2 service visits and improves production from the start.
Calculate your system with shade
Tick 'partial shade' in the calculator and pick your inverter — the bill of materials adjusts automatically with the right optimizer.
Open the free calculator