Renewable energy is an interesting topic. Most people end up being only partially informed about the different ways that renewable energy can be produced. Often this manifests itself as a negative attitude towards hydro ("damming up our rivers!!!!") and a positive one towards wind and solar. Being in the hydro business I have always found myself to be interested in all types of renewable energy though hydro is the best. :)
What I have REALLY been interested in is the combination of the different types. A hydro site has what we call "parasitic load" which is power that the plant needs to use in order to stay running: lights, computers, pumps, etc. In general, our contracts with the utilities require us to but the power we use for the parasitic load BACK from the power companies rather than use some of the power we generate. We are required to sell every bit of what we generate. This is a perfect opportunity for secondary power generation. I suggested the use of solar or a small wind turbine to offset the parasitic load many many years ago. It just seemed like it would be awesome to have a renewable energy site that was fully renewable. (hmmm... that could be a bigger topic for another post)
And so...
This solar site produces 45kw/h at about 14% efficiency. Our expectation is that it will offset roughly 57,000 kw of parasitic load. But what does that mean?
So at peak efficiency, the solar panels will produce 45 kw of power every hour. That would be 393,000 kw per year IF they could operate at peak output 24 hrs/day (45 kw/h x 8736 hrs/year). Since it's solar and the sun goes down each day that's not possible. So you get an efficiency rating. Solar can realistically generate about 14% of it's potential potential power. So 393,000 x 14% = 55,000 kwh.
But what does THAT mean? So, an average household in 2011 used between 9,000 and 11,000 kwh of power in a year. So a solar site the size of the one we just put in (note the tire tracks for scale) would power FIVE or SIX houses for a year. Not very many.
On top of that, 14% doesn't sound very good does it? That's part of the problem with solar and why it so dang hard to really get solar onto the grid. They just take up so much space for so little power...
So how does that compare with hydro?
Hydro tends to be about 60% efficient. Hydro can run 24/7 but the efficiency takes into account water flow variation for dry seasons. The site that this is installed at is our smallest site which is on the very small side of small hydro. This site generally produces around 3,000,000 kwh per year. We call it a 600 kw site. That tiny hydro site will provide power for roughly 300 families.
Three hundred.
That's why we put so much effort into getting these small plants up and running. Hydro has such an excellent efficiency (compared to other renewables) that even a small plant can make a difference. For the record, wind power tends to have about a 20% efficiency.
Despite all that, I love the idea of a Hydro plant using solar to offset it's parasitic load. It's brilliant. If more businesses did that it could really make a difference. That's where it needs to happen: businesses or perhaps neighborhoods. Small solar farms providing power to a neighborhood or business is awesome. Instead of one big farm we could have a bunch of small ones all over the place. Solar has "easy" going for it. No moving parts and no complicated systems. Just set it up and go. They're bigger than you think, we just need to think bigger.
