Process for producing polycrystalline silicon granulate in a fluidized bed reactor, wherein in a fluidized bed region continuously supplied seed particles are fluidized in a fluidized bed by means of a gas flow, wherein the fluidized bed region is heated with a heating apparatus, wherein supply of a feed gas stream comprising hydrogen and silane and/or halosilane causes elemental silicon to be deposited on the seed particles to form the polycrystalline silicon granulate and wherein in a continuous process the silicon granulate is discharged from the fluidized bed reactor as a product stream, wherein as a responding variable the fluidized bed temperature Tws is determined as the temperature T offgas,WS of an offgas stream from the fluidized bed region ṁ 22,offgas,WS by means of the mass and energy balance of a balance ambit I and/or a balance ambit II, wherein the balance ambit I is composed of the - enthalpy Ḣ 16 of the feed gas stream ṁ 16,feed gas, - enthalpy Ḣ 21 of a seed particle stream into the fluidized bed region ṁ 21,KP,WS, - enthalpy Ḣ 18 of the product stream ṁ 18, Product, - enthalpy Ḣ 22 of the offgas mass flow from the fluidized bed region ṁ 22,offgas,WS, - reaction enthalpy Δ R H 23, - heating output of the heating apparatus Q 20, - energy removal from the reactor in the fluidized bed region Q 24; and the enthalpy of the offgas stream Ḣ 22 for the balance ambit I is given by equation H ̇ 22 = H ̇ 16 − H ̇ 18 − Q 24 − Δ R H 23 + Q 20 + H ̇ 21 and wherein the balance ambit II is composed of the - enthalpy Ḣ 21 of the seed particle stream into the fluidized bed region ṁ 21,KP,WS, - enthalpy Ḣ 17 of the seed particle stream into the reactor ṁ 17,KP,Reactor, - enthalpy Ḣ 22 of the offgas mass flow from the fluidized bed region ṁ 22,offgas,WS, - enthalpy Ḣ 19 of an offgas stream from the reactor ṁ 19,offgas,Reactor, - energy removal from the reactor in the region above the fluidized bed Q 25 and the enthalpy Ḣ 22 of the offgas stream for the balance ambit II is given by equation H ̇ 22 = − H ̇ 21 + H ̇ 17 − H ̇ 19 − Q 25 wherein the temperature of the fluidized bed Tws is given by equation T WS = T offgas, WS = H ̇ 22 m ̇ 22, offgas, WS ∗ c p, 22, where ṁ 22,offgas,WS = offgas mass flow c p,22 = heat capacity of the offgas stream, and wherein the responding variable Tws is in a range from 700°C to 1200°C and according to Tws at least the heating output Q 20 is as a manipulated variable controlled such that Q 20 is in a range from 0.5 to 3 kW per kilogram of silicon in the fluidized bed. - enthalpy Ḣ 16 of the feed gas stream ṁ 16,feed gas, - enthalpy Ḣ 21 of a seed particle stream into the fluidized bed region ṁ 21,KP,WS, - enthalpy Ḣ 18 of the product stream ṁ 18, Product, - enthalpy Ḣ 22 of the offgas mass flow from the fluidized bed region ṁ 22,offgas,WS, - reaction enthalpy Δ R H 23, - heating output of the heating apparatus Q 20, - energy removal from the reactor in the fluidized bed region Q 24; and the enthalpy of the offgas stream Ḣ 22 for the balance ambit I is given by equation H ̇ 22 = H ̇ 16 − H ̇ 18 − Q 24 − Δ R H 23 + Q 20 + H ̇ 21 and wherein the balance ambit II is composed of the - enthalpy Ḣ 21 of the seed particle stream into the fluidized bed region ṁ 21,KP,WS, - enthalpy Ḣ 17 of the seed particle stream into the reactor ṁ 17,KP,Reactor, - enthalpy Ḣ 22 of the offgas mass flow from the fluidized bed region ṁ 22,offgas,WS, - enthalpy Ḣ 19 of an offgas stream from the reactor ṁ 19,offgas,Reactor, - energy removal from the reactor in the region above the fluidized bed Q 25 and the enthalpy Ḣ 22 of the offgas stream for the balance ambit II is given by equation H ̇ 22 = − H ̇ 21 + H ̇ 17 − H ̇ 19 − Q 25 wherein the temperature of the fluidized bed Tws is given by equation T WS = T offgas, WS = H ̇ 22 m ̇ 22, offgas, WS ∗ c p, 22, where ṁ 22,offgas,WS = offgas mass flow c p,22 = heat capacity of the offgas stream, and wherein the responding variable Tws is in a range from 700°C to 1200°C and according to Tws at least the heating output Q 20 is as a manipulated variable controlled such that Q 20 is in a range from 0.5 to 3 kW per kilogram of silicon in the fluidized bed. ṁ 22,offgas,WS = offgas mass flow c p,22 = heat capacity of the offgas stream, and wherein the responding variable Tws is in a range from 700°C to 1200°C and according to Tws at least the heating output Q 20 is as a manipulated variable controlled such that Q 20 is in a range from 0.5 to 3 kW per kilogram of silicon in the fluidized bed.