Moving from 10 to 15 kW increases rated array size by 50%, but does not necessarily increase savings by 50%. If the extra output arrives when demand is already met, it mainly becomes export or curtailment. Measured demand should drive the decision.
When this size deserves assessment
A home with electric heating and vehicle charging, or a small business operating during daylight, may justify a larger array. These are use cases, not automatic approval criteria. Supply capacity, installation rights, roof space and applicable connection conditions must all be checked.
Separate present consumption from future loads. A planned electric vehicle with flexible midday charging has a different solar profile from an identical vehicle charged only overnight. Annual energy totals conceal that difference.
From modules to electrical design
With hypothetical 450 Wp modules, 33 panels provide 14.85 kWp and 34 provide 15.30 kWp. String length, temperature-related voltage limits, input current and shading per MPPT must be checked. Extra panels cannot simply be added to an existing inverter without design verification.
Roof layout must allow maintenance access and suitable structural fixing. Cable routes, earthing, surge protection and inverter location can change the price even when panel capacity stays constant.
Generation versus useful energy
| Hypothetical specific yield | Annual energy from 15 kWp |
|---|---|
| 1,300 kWh/kWp | 19,500 kWh |
| 1,500 kWh/kWp | 22,500 kWh |
| 1,700 kWh/kWp | 25,500 kWh |
These are arithmetic examples, not guaranteed Crete production figures. Start a location-specific assessment with PVGIS, then account for local shading and installation losses.
At an illustrative 22,500 kWh annual output, 60% direct use gives 13,500 kWh, while 35% gives 7,875 kWh. The same array can therefore deliver different financial outcomes. Neither percentage is a measured project result.
Comparing proposals
Ask for two system sizes modelled against the same load profile. Compare additional capital cost, incremental direct use, surplus and storage requirements. Check equipment models, warranty terms and exclusions. Connection approval and export compensation must not be assumed.
Explore commercial solar, our PV installation service and the published 25 kW Paleochora fuel station project as a different commercial-scale example. We do not present an unverified 15 kW case study.
Check peaks as well as annual kWh
With larger loads, simultaneous operation of air conditioning, pumps or business equipment affects electrical design. Record which devices run together, when peaks occur and whether expansion is planned. Peak load power is not the same as annual energy demand.
For 15 kW proposals, ask for a clear distinction between module DC capacity and inverter capacity, a site layout and estimated self-consumption by operating period. If storage or backup is proposed, request a separate description of the loads that can actually be supplied.
Discuss your installation
Send your location, bills, operating hours and available roof space for an individual assessment.
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