This study attempts to optimize and examine the techno-economic feasibility of off-grid hybrid renewable energy systems (HRES) to satisfy simultaneously electric, heat and hydrogen load of a large energy consumer. An innovative method is adopted so as to recover surplus electricity to generate heat and cut emissions. The system is comprised of solar panels, wind turbine, diesel generator, electrolyzer and boiler to supply 9910 kWh/day of electricity, 14 kg/day of hydrogen and thermal energy in five different major cities in Iran, namely Bandar Abbas, Shiraz, Tabriz, Tehran and Yazd. These figures are computed on average and the thermal load differs according to yearly weather temperature, which are 75, 22, 2000, 5200, 2200 and 1800 kWh/day respectively. To serve this purpose, HOMER Pro software was used and thermal load controller (TLC) (including electric boiler) was added to generate thermal energy by converting excess electricity of renewable energy production. Thus, a decrease in conventional fuel consumption, emissions and cost of energy (COE), as well as an increase in the renewable fraction of HRES without increasing project's size would be achievable. To meet peak demand and avoid intermittent behavior of HRES, a 1000 kW generator was picked up. Results indicate that recovering extra electricity can enhance renewable fraction by up to 35% and bring down COE and exhausted CO2 by 7.1% and 10.6% respectively, which highlight the necessity of TLC in HRES, chiefly in off-grid systems.