Solar Energy System

It's time to talk about photovoltaic (PV) solar power ... again !!!

Why?

Look at your utility bill ... thats why !

You'll find plenty of pictures below to see an actual installation in progress.

The interesting thing, before starting with the technicals, is that local utility companies (like PG&E, who provides my power) actually are happy to see these types of systems come online.

Huh, don't they lose mony when you install a system? Well, sort of, but these systems also do something even more important, so they lose some money while avoiding spen a lot more money, so for now they appreciate them, and are very supportive in efforts to bring residential solar power systems online.

So what do these systems offer the utility companies that is so important?

PEAK DEMAND ENERGY !

The majority of power is consumed during peak hours (afternoons here, with air-conditioners being the major draw), and solar systems do their best exactly when the peak demand occurs. So when someone down the road needs power to run their A/C, its may actually be my solar system that in a small way provides them the power they need.

How does this benefit the utility company? It means they now have an additional source of power during these peak periods, freeing them up from having to spend hundreds of millions of dollars to build "peaker plants", designed to do nothing other than to occasionally provide additional energy during peak hours. They can use my power (and all other PV generated power), rather than build a peaker plant, or figure out how to build another dam, or nuclear plant (and YES ... we need to get back on track designing & building the next generation of nuclear power plants.)

So, here's whats going on with PV solar power, and why i'm a happy camper.

First the numbers, my PG&E bill on average is $450/month (we have no gas service where we live, so my heating is provided via a 100 Amp reversible heat pump, OUCH!!!)

My solar system retailed for $108K, California rebates brought the price down to $72K, and since i asked the supplier if i could install it myself, he brought the price down another $18K, total out-the-door costs were $54K (most residential customers can benefit from a system one half to one quarter the size of my system, i just have unusually large demand needs.)

Guess what? After adding back in construction costs (wire, steel framework, permits, etc.) and financing it all for 15 years ... my system cost me $450/month.

I'm already break-even, and when energy rates go up, my bill would hypothetically have gone up to $500/month, but instead it will remain fixed at $450/month, based on my fixed-rate loan.

The loan has a 15-year term, and the lifetime of the system is 25 years. That means for 15 years i pay what i'm paying right now, when rates go up over the next 15 years i still pay the same ... and for years 16-25 i pay NOTHING for a system that is now providing 10 years worth of pre-paid power!

Read all this very carefully, do the math on your bill, create a spreadsheet to analyze your power costs over then ext 25 years, and you will likely find you can benefit from a system like this too.

Hello new age of residential electrical generation, i'd like to introduce you to a very happy new owner ... me !!!

OK, here are the technicals, i will provide lots of pictures, and will respond intelligently to any real questions that come in.

this is a great example, because it incorporates both a roof-mount array (less work, but i don't like the idea, in case you ever have to fix a roof leak), as well as a ground-mount array (more work surprisingly) ... most people opt for a roof array, because they think they don't have "space" for a ground mount system. Be creative, a ground mount system is a little more up-front expensive, but much easier to work on and service over the lifetime of the system.

A little background first, my system is tied into a 3-phase 400 Amp electric drop ... this is something you need to consider right away. If you have an older 100 Amp electric service panel, chances are very good you will have to upgrade your panel as well, to accommodate the additional amperage a PV system places on the electric panel bus (the additional cost of upgrading your electric panel should definitely be a part of any payback calculations.)

I run both standard 400 Amp 120/240V service, as well as 3-phase 480V power for an agricultural well (to irrigate the orchards.) I tied half the system to the residential side of my service, because that is where the majority of our power demand comes from, also PG&E pays more for residential generated power than commercial power.

Here is a picture of the overall electrical panel installations (all pictures taken during work-in-progress):

Here is a picture of the 400 Amp residential electric panel and bus:

Here's a picture of the electric service drop (weatherhead): 

And here is a picture of the overall panel installation:

Going into more detail about the ground mount system, here is a picture of the piers (those are 12 inch tubes, dug 4 feet down into the ground! It turns out solar panels do not fall down, they tend to get picked up by the wind and fly away for hundreds of yard, coming down with catastrophic results.) You can also see the 1 1/2 inch galvanized steel pipes used to create the framework to mount the rail system to, along with the brackets used to mount the rail system to the pipes (very clever stuff!)

Here is a view from underneath the ground mount system (wires will be neatly tucked/routed later):

And here is a detailed picture of the way the rail system mounts to the galvanized steel frame system:

Here is a picture of the roof system, the panels mount to the same rail system, the only difference is that instead of using clamps to mount the rails to the pipes, there are brackets that lag bolt through the roofing material directly into the rafters:

Power comes from the panels to an electric box called a combination box (combi-box):

From the combi-box, an inverter turns the power from 12V DC to 120V AC :

The roof and ground systems combine the power into one electrical sub-panel :

Which sends the power to the solar system main fuse disconnect :

Which feeds the power INTO the house 400 Amp residential electrical panel, so when I need power it is pulled directly from the solar system instead of being supplied by PG&E. Whats interesting is that when more power is generated than used, PG&E takes the excess power (making the meter spin backwards) and pays the current rate for power based on time of day (special meters called "time of use" meters are installed when you have a solar system.) Since my system generates the most power when demand is highest (during peak use), I get the maximum credit for the power I generate (SWEET!!!)

Here is a picture of the overall electric solar boxes (work in progress photo) :

For the electrically curious, here are some pictures of a 400 Amp bus gutter used to bring both residential power and 3-phase power to one location (look at the size of those copper wires, referred to as "500's), they are as round as a penny, and cost a lot more than that), along with a picture of a 100 Amp 3-phase panel, and a well pump starter motor control box :

I hope this helps a little bit in understanding whit I believe will be a major future component of electrical generation. If you have any questions, please feel free to e-mail me at : jeff AT inspect DOT net

It's been quite an experience getting this whole project done, but in doing it almost exclusively by myself (thank you very much Rich Araujo!) I learned a lot, and am writing to share the information with whoever else may benefit.

If you live in sunny California, and you do not migrate to PV solar power before the rebates go away, you are as silly as the people who did not buy a prius and received a free carpool sticker along with substantial rebates.

I believe we can do whats best for this country and ourselves by generating our own electric power, instead of buying oil from regimes that hate us. It really may be one of the most direct ways we can support our troops, if you ask me.

Stay strong, and remember we need to pass this planet on to the next generation, so its YOUR job to make sure its better than when you took it over.

Are we doing our parts ... really, are we doing our part to ensure this happens ???

Its a beautiful thought to consider it is the sun that makes my trees grow, they absorb carbon monoxide which helps the environment, they also yield a cash crop (buy almonds, a can a week, thats all we ask :) and it is technology that allows me to create the complete ecosystem necessary to do it all for free (from my perspective) for the next 25 years !!!

We can ALL do our part ... if you have question, i will answer them as best i can, and steer you in the right direction so you can reach a logical conclusion that is best for you.

As an engineer, I say to every other engineer REALLY working on this problem, and every laborer putting these systems in place ... YOU ABSOLUTELY ROCK !!!

Power to the people :)

Cal Poly, Learn By Doing !