What is a PV string?
A photovoltaic, or PV, string is a group of solar panels connected in series. Their voltages add; parallel strings increase combined current [S1]. In an assumed example, 10 panels each at 40 volts give 400 volts before temperature corrections. Ask for the string layout and inverter limits alongside the roof plan. Checked October 2026.
What does a PV string mean for your site?
A photovoltaic (PV) string is a group of solar panels connected in series [S2]. The electrical grouping is part of the design, rather than simply a row drawn on the roof plan.
For your site, it matters because panel count and grouping must fit the inverter and roof conditions. Ask for a string schedule identifying which panels share each circuit, alongside the equipment specifications.
How do panel count and inverter limits affect a string?
An illustration, not a quote: assume 10 identical panels each have an open-circuit voltage of 40 volts. Their series voltage is 10 × 40 = 400 volts before any temperature correction. This arithmetic is not a safe design limit. The IET explains that cold conditions increase the voltage that equipment must accommodate [S1].
The designer checks the inverter’s start-up and maximum voltage, plus current limits. Strings connected in parallel increase combined current [S1]. Ask for those checks in the design documents rather than choosing a panel count from roof area alone.
How should shading and different roof faces be assessed?
Request a layout assessment for chimneys, vents and neighbouring roof faces. Shade can create reverse-voltage conditions in modules, which bypass diodes help address [S2]. Ask the designer how the proposed grouping and maximum power point tracking (MPPT) inputs respond to the surveyed conditions. Do not assume a fixed loss percentage or that extra electronics recover all shaded output.
Read how commercial solar panels work, solar capacity in kWp and commercial solar cost data for shared basics. Switching the inverter off does not remove string voltage [S3]; arrange inspection through someone competent in solar electrical work.
Next step
Consider cutting energy costs and the site check, then get matched with an installer that covers your area.
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Common questions
Does adding panels in series add their currents together?
No. Series connections add voltage; connecting strings in parallel increases combined current [S1].
Can you extend a string whenever roof space becomes available?
The designer must reassess voltage and current limits, including the inverter's operating range and cold conditions, before changing panel count [S1].
Do bypass diodes make shading irrelevant?
No. They address reverse-voltage conditions arising from shading; they do not restore missing sunlight [S2].
Are strings on different tracker inputs automatically one parallel group?
No. The IET distinguishes strings connected to the same tracker from those on separate trackers [S1].
Is switching the inverter off enough to remove string voltage?
No. The IET explains that stopping current flow does not remove the potential from PV strings [S3].
Ask about your site
Sources
- Solar photovoltaic DC switch-disconnector selection and configuration, Institution of Engineering and Technology,Last checked 19 October 2026
- Solar photovoltaic power supply systems, series strings and bypass diodes, Institution of Engineering and Technology,Last checked 19 October 2026
- Exploring wiring systems for unearthed DC solar PV systems, part 2, Institution of Engineering and Technology,Last checked 19 October 2026