Hi,

The issue is caused by the sequence generation happening both when the record is initially created and when it's read/displayed due to the readonly property.

To fix this issue, you can remove the default sequence generation from the field definition:

name = fields.Char(string="Name", required=True, readonly=True)

Instead, override the create method of your model to generate the sequence only once when the record is created:

@api.model
def create(self, vals):
vals['name'] = self.env['ir.sequence'].next_by_code('pv.plant.sequence')
return super().create(vals)

Also, make sure that the XML code is also correct:

<record id="sequence_pv_plant" model="ir.sequence">
<field name="name">PV Plant Sequence</field>
<field name="code">pv.plant.sequence</field>
<field name="prefix">PV</field>
<field name="padding">4</field>
</record>

Hope it helps