Modules & Mounting — how the park is built technically
In short: The technology choice determines yield, cost and maintenance. Today's standard is monocrystalline silicon with 21–23 % efficiency, often as a glass-glass bifacial module, on a single-axis tracker structure or fixed mounting. Trackers add roughly 10–15 % extra yield, but cost more and require more maintenance.
Module technologies
| Type | Properties |
|---|---|
| Monocrystalline silicon (standard) | 21–23 % efficiency, long service life, market leader |
| Bifacial modules | Rear side additionally active (albedo effect) — typically +5–8 % yield over normal grass, more over bright ground |
| Glass-glass modules | Long service life (25–30 years performance warranty), higher weight |
| TOPCon / HJT (new cell technologies) | Higher efficiency (up to ~24 %), price premium |
| Thin film (CdTe, CIGS) | Niche in large parks; specialist manufacturers such as First Solar |
Mounting: fixed vs. tracker
| Variant | Extra yield | Added cost / risk |
|---|---|---|
| Fixed south-facing mounting (standard) | Baseline yield | low CAPEX, hardly any maintenance |
| Fixed east-west mounting | smoothed daily profile, often −5 % annual yield, but more stable across the day | comparable to south-facing |
| Single-axis tracker (north-south axis, east-west tracking) | +10–15 % annual yield, depending on site | +5–15 % CAPEX, motors/sensors more maintenance-intensive |
| Dual-axis tracker | +15–25 % possible, but only worthwhile with high direct irradiation (rarely attractive in Germany) | significantly higher CAPEX, high maintenance |
| Vertical bifacial modules (east-west) | daily profile with a double peak (morning/evening), total slightly below south-facing | specialised mounting, suited to agri-PV |
What drives the choice in practice
- Site: in southern Germany with high direct irradiation, trackers pay off sooner than in the cloudier north.
- Land type: agri-PV favours vertical rows, normal grassland uses fixed mounting or a single-axis tracker.
- Investor profile: tracker installations deliver higher absolute yield and are attractive for PPA models; classic EEG (Renewable Energy Sources Act) projects are often fixed-mounted.
- O&M strategy: those doing their own maintenance tend to choose trackers; those wanting a full O&M contract choose fixed.
Modules and mounting — technology comparison, tracker options and decision matrix
Frequently asked questions
How long do the modules really last?
Manufacturers specify 25–30 years of linear performance degradation (e.g. after 25 years still ≥85 % of the initial output). Real long-term data confirm the trend for established manufacturers; with no-name modules the warranty is only worth as much as the manufacturer staying in the market.
Is bifacial worth the premium?
Clearly so over bright ground (gravel, snow); over normal grass, a moderate extra yield for a small premium. A standard decision in today's large-scale projects.
What happens if modules fail?
Individual modules can be swapped, and the full O&M contract covers the logistics. For larger serial damage (e.g. PID, glass breakage from hail), insurance applies.