What to put on a flat roof

A simplified rendering of my rooftop with solar collectors. Don’t worry, the real building does have windows and doors.

In a way, all those homes with conventional pitched roofs are missing out on certain house function opportunities.  Consider what many commercial buildings put on the roof:  heating, air conditioning, ventilation, skylights, and nowadays, solar panels and sometimes even live roofs.  All out of sight, quietly performing their respective duties.

Now that I have such a resource, I intend to place solar panels and beehives up there.  And instead of having  a ground level AC compressor, I can put it on the roof and avoid the  noise and heat from such a unit on the ground.  The backyard deck will be safe from its intrusion.

Innovative Power Systems (IPS) is the dominant alternative energy resource in our area.  There are many other solar energy companies now, but IPS has been around since before renewable energy became popular, and has established a solid reputation.  I’ve been following their projects for years and engaged them at the Living Green Expo in May.  They followed up on my inquiry and interest and I now have a proposal for installing an array of photovoltaic collectors on my flat roof.

It calls for 13 panels, each about 200W of peak power for a total of 2.5kW.  It looks like it takes 2/3 of the roof space, stopping short of that miserable chimney structure.  The estimate is that it will generate about 3 megawatt-hours of electricity in a year.

This sounds good, but still, I wonder.  I suspect that I have a large appetite for electrical energy.  I don’t have the calculations at hand, but I seem to recall that in my (large) Minnetonka home, I went through 13 MW-hours in a year.  I am surely more conserving today, but what about that electric vehicle in my future?

And why not generate more than I actually use?  The surplus is delivered to the grid and, with other solar installations, reduces the power drawn from conventional coal plants, and avoids the need to build new ones or add capacity.  I don’t know how the utilities feel about this; I suspect they would rather keep scaling their business and selling to the old model, but in progressive states like Minnesota, forward thinking lawmakers have required that utilities provide a minimum fraction of their power from renewable sources.  I’m not going to feel sorry for the utilities, I’m glad we have a path outlined to what will eventually become the norm.  Central power generation may never go away completely, but in these times of peak oil, a managed strategy for renewables to replace fossil fuels seems like a really good idea.