DIY Solar Panel Kit 320W – 72 Mono Cells 6x6

The MR WATT 320W DIY solar panel kit contains 72 grade-A monocrystalline 6"x6" (156x156 mm) solar cells plus the accessories to connect them. With 72 cells in series you build a 24V nominal module with the same layout as classic 72-cell commercial panels; alternatively you get two 160 W 12V panels. We designed this kit in-house.

A real rooftop module: what to consider before building it

• Size: in 6 rows of 12 cells the cell area is about 95x191 cm, almost two metres. You need a workbench that big and a helper to handle the finished panel.
• Weight: the cells weigh little, but a panel this size encapsulated in 3-4 mm tempered glass with an aluminium frame easily reaches 18-22 kg. Anchors and structure must be sized for the weight and for wind.
• Current: at about 8 A and 38 V the 24V module connects easily to an MPPT controller; two 12V panels in parallel exceed 16 A instead and need thicker cables.

K72ML3-AH technical specifications

Soldering and encapsulation

Two 12V panels in 4 rows of 9 cells measure about 63x143 cm each. Sizes assume 3 mm between cells, frame excluded. You need a 60-80 W soldering iron with a flat tip, a smooth heat-insulating surface and an encapsulation method (EVA, clear silicone resin such as QSIL 216, or double glass), not included. Guides and videos are in the Learning Zone on mrwatt.eu and on our YouTube channel MRWattDIY.

What you can do with it every day

In Southern Europe 320 W produce on average about 1.2 kWh per day over the year, over 1.3 kWh on summer days. In a weekend cabin or mountain hut that covers LED lighting throughout, a 12V or 24V fridge, phone and laptop charging, a water pump and a few hours of TV in the evening, with a suitably sized battery.

Frequently asked questions

What exactly is in the kit?

72 grade-A monocrystalline 156x156 mm solar cells, a few spare cells to make up for breakages during soldering or shipping, tab wire and bus wire, flux and a Schottky diode. The soldering iron, encapsulation materials, frames, junction boxes and charge controller are not included.

Which controller do I need for 320 W?

A controller is always required, because connecting the panels straight to the battery overcharges it, with a risk of electrolysis and explosion. On a 24V battery you need at least a 15 A controller; on a 12V battery with the 24V module you need an MPPT rated at least 30 A, because at 12V the charging current reaches about 24 A.

One 24V module or two 12V panels?

The single 24V module halves the cable current and needs only one structure, but it is big and heavy. Two 12V panels are easier to handle and can sit on two different roof slopes, provided you use thicker cables and a blocking diode for each: one is included, the second must be bought separately.

Can I connect it to my home grid?

No. Self-built panels lack the certifications required for grid-connected systems: the kit is designed for off-grid systems with a battery and charge controller.

How long does it take to build?

With 72 large cells, allow a couple of days. Solder a 12-cell string first, measure its voltage in the sun (about 6-7 V), then carry on with the others. The spare cells included cover the most common breakages.