How to choose solar panels for a DIY build
Monocrystalline vs polycrystalline, rigid vs flexible, and how to read a panel's specs — plus how to wire panels in series vs parallel for your system.
Panels are where most people start shopping and where a surprising number of builds go wrong. Pick the right type and voltage and everything downstream gets easier. Here’s how to choose — and how to wire them once they arrive.
Monocrystalline vs polycrystalline
- Monocrystalline panels are more efficient (more watts per square foot), perform better in low light, and cost a little more. For DIY builds where roof or ground space is limited — vans, RVs, small roofs — mono is almost always the right call. Our panel picks are mono for this reason.
- Polycrystalline is cheaper per watt but less efficient. Fine if you have unlimited space and a tight budget; otherwise, mono wins.
Rigid, flexible, or portable?
- Rigid glass-and-aluminum panels are the durable default — best output, longest life, cheapest per watt. Use them anywhere you can mount them solidly.
- Flexible panels bend to curved surfaces (van roofs, boats) and are light, but they run hotter, are less efficient, and don’t last as long. Use them only where rigid won’t fit.
- Portable/folding panels are for power stations and camping — grab-and-go, not permanent.
How to read the spec sheet
Four numbers matter:
- Watts (W): the panel’s rated output in full sun. This is what you size around — see sizing your system.
- Vmp / Voc (volts): the operating and open-circuit voltage. This determines how you can wire panels together and whether your charge controller can handle the array.
- Imp / Isc (amps): the current. Matters for wire and fuse sizing.
- Efficiency (%): how much sunlight becomes electricity — higher means more watts in less space.
Series vs parallel — the choice that matters
When you have more than one panel, you wire them one of two ways:
- Series adds the voltages (two 20V panels = 40V) while current stays the same. Higher voltage means thinner wire and less loss over distance — great for rooftop runs — but more shade-sensitive, and you must stay under your controller’s max voltage.
- Parallel adds the currents while voltage stays the same. More shade-tolerant, but higher current means thicker (more expensive) wire and a combiner fuse per panel.
Many DIY builds use a mix. An MPPT controller (like the Renogy Rover) makes series wiring especially worthwhile because it converts that higher voltage into extra charging amps.
Don’t forget the connections
Panels almost always use MC4 connectors. Get proper solar cable with MC4 ends rather than improvising, and put a correctly rated PV fuse or breaker on the array. Wiring and protection are covered in how to wire your panels.
The bottom line
For most DIY builds: rigid monocrystalline panels, wired in series into an MPPT controller when you can. Match the array voltage to your controller, size the wire to the current, and buy one more panel than you think you need. Browse our solar panel reviews to start, then size the rest of the system.