Original sentence: Grid connected solar cells can be cost effective in a spot-priced market because they generate electricity during peak usage periods when electricity is most costly and because they produce electricity at the point of use thereby avoiding transmission costs.Many forms of renewables are cost effective in remote, underdeveloped, and/or low population density areas that are off the grid or on unreliable grids.Solar thermal is already cost effective for water heating.Some renewable sources are diffuse and require land and  construction material for energy production.The fact that small diesel generators are not hugely efficient and the fact that they consume fuel and make noise even when offload also makes renewables more desirable in this situation
Edited sentence: Grid connected solar cells can be cost effective because they generate electricity during peak usage periods when electricity is most costly and because they produce electricity at the point of use thereby avoiding transmission costs.In developed urban locations, solar thermal is already cost effective for water heating, particularly swimming pools.Many forms of renewables are cost effective in remote, underdeveloped, and/or low population density areas that are off the grid.Some renewable sources are diffuse and require large land areas and great quantities of construction material for significant energy production.The fact that small diesel generators are not hugely efficient and the fact that they consume fuel and make noise even when offload also makes renewables seem more desirable in this situation.There is some doubt that they can be built out rapidly enough to replace fossil fuels