This paper presents comparison of the proposed power capacity,efficiency and harmonic include (THD) of Inverter different size. In order to know the effects of the electrical system, requirements according to the standard of Provincial Electricity Authority (PEA). Guideline for the selection of inverter used in the production of electricity of the solar system installed on the roof top grid connected. To the policy of the Department of renewable energy and energy conservation. Promoted to be installed for the Thailand country.