def start_requests(self):
        fromdate = date.fromisoformat(getattr(self, 'fromdate', date.today().isoformat()))
        todate = date.fromisoformat(getattr(self, 'todate', date.today().isoformat()))
        url = "https://ipnew.rbp.eu/Fgsz.Tso.Data.Web/mvc/TsoData/GetFactDailySetList"
        day_count = (todate - fromdate).days + 1
        for single_date in (fromdate + timedelta(n) for n in range(day_count)):
            body = {
тут немного длинный боди с single_date} 
            body = dumps(body)
            filename = self.download_path + 'FactDailySet.Export.{}.xlsx'.format(single_date.isoformat())
            yield Request(url=url, body=body, method='POST', callback=self.parse, meta={'filename': filename})

def parse(self, response):
        filename = response.meta['filename']
        j_data = loads(response.body)['data']
        df = pd.DataFrame.from_dict(j_data)
        df.to_excel(filename, sheet_name='FactDailySetExport', index=False)