A novel Multi-Input Multi-Output (MIMO) step-up DC transformer for applications in high voltage renewable energy sources is designed and presented. This design topology can provide a high step-up conversion gain without using an internal AC transformer, to supply different DC output voltage levels from integration of various input power sources. MIMO DC transformers provide flexibility in terms of choice and availability of the power source, reduction in the number of power lines used to transfer power to pre-specified locations as well as enhancement in system reliability. The comprehensive operating principle, theoretical analysis and design criteria of the proposed MIMO step-up DC transformer have been discussed. The proposed DC transformer has the advantages of simple configuration, fewer components, high conversion gain and high efficiency. The relations between the inputs and outputs are expressed mathematically in terms of passive components and the duty cycle of power switches. Also discussed is the sizing of the employed inductors and the capacitors for a particular application. The derived input and output expressions for ideal and non-ideal DC transformer are solved numerically and the results are validated against those obtained through MATLAB-SIMULINK simulation. Tentative analysis of the numerical and simulation results shows a close correlation.