Reviewing the Search for an Ann Arbor Solar Installer

We are about to sign a contract for a significant solar Photo Voltaic (PV) energy system for our home and I was reviewing the research & decision making process we just went through.

It started about 9 months ago with online research into complete systems being sold by national vendors and research on the DTE website about the DTE programs.

Going from the offerings of complete systems I tried to understand the individual component choice and the important specifications for the panels, inverters, and interconnects.

I originally focused on the Enphase microinverter technology because I’d be very comfortable doing that kind of installation myself as the voltage is limited to 230VAC just like any home electric panel. However, I found out that to get the DTE credits and the tax credits I have to have a licensed electrician do the install.

No problem, I thought, I could work with an Ann Arbor electrician and I know quite a few from my “day job” in the real estate industry. However when I started talking to electricians nobody seemed too excited about solar installations.

It was also about this time that the wife said she really wanted the solar panels to be able to produce some kind of energy even if the grid was down in an emergency situation. (We’ve had a back-up generator for 12 years now but I understand and agree with her logic. It would be a shame to have 7 or 8 thousand watts of generating capability on the roof during a blackout and not be able to use any of it.)

That decision removed the Enphase microinverter option from the table. So more study.

It turns out that if you want to have one of the popular battery back-up systems you end up spending a lot of money on batteries. Even if you only need it for emergencies. These systems take the solar energy and pump it into batteries, then take the battery voltage and convert it into AC for your home.

So you need two electronic products, a charge controller to charge the batteries, and an inverter to convert the 12 to 48 volt DC output of your battery bank back to 240AC for your home use.

Sounds easy enough, except that those systems involve more compromises on the rest of the design.

In fact, too many compromises based on the idea that we’ d only use it during emergencies.

So here is the compromise I came up with:

Buy a normal grid-tie system, but leave some “hooks” in the design so I could install a small charge controller, battery bank, and inverter system later for emergencies.

The only challenge left was that the charge controller products are normally designed for a maximum solar array voltage of 200 to 300 volts. (The grid tie optimum is a maximum of 600 volts.)

I proposed to have the roof “strings” of panels divided into say three 200V strings that would be tied in series at an accessible combiner box before being sent to the grid tie inverter. But I got some confused looks from the vendors I was talking to. About this time (October 2010 actually) one company announce that they were introducing a high voltage charge controller that could work with voltages up to 600 volts. That kind of solved the problem. Assuming we can afford one of those when the go into production early in 2011 we should have a fairly straight path to an emergency back-up system without loosing the optimization of the grid tie system.

At that point then I was ready to get quotes and move ahead.

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Optimized Ann Arbor Solar PV Installation – Decision, Almost-

We should see the fourth bid today from a local contractor.

But, we are seeing some standouts in the cost/benefit idea. First, it looks like some Chinese solar panels are probably the best value per dollar. But, we can potentially buy ones made domestically for about $19.00 per panel more. That will probably end up being about $800.00 but we kind of feel it is probably worth it to buy domestic production.

On the inverter side, the Sunny Boy product line seems to be the most cost effective. We have a proposal that squeezes every watt of capability out of the SMA8000 unit. That product in made in Germany. I guess before we pull the trigger I need to review the domestic inverter companies, but I don’t think they will be competitive at this point.

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Another useful Solar Design website

Hopefully this Monday we will be making our decision. I was interested in finding some more data on Schott solar panels and I came across this site:

I haven’t signed up to use it yet but I was able to do some inverter comparisons that were quite useful. It is better than the Sharp, SMA, and other design sites in that it allows you to compare components from multiple manufactures and it has an ability to sketch the layouts of the panels on the roof.

Very cool!

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Another Possible Inverter Manufacturer – Solectria

As I was studying potential compnents for our Ann Arbor residential solar array I ran across a new option.

Solectria inverters may be made in the US so that gives them a couple points in my book.

They seem to have a very wide operating voltage range and a wide MPPT range.

And, they are very cost competitive with the SMA Sunnyboy line.

Finally, they do have a string sizing tool on their website here:

Solectra Residential Solar Inverter

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Which Solar Panels For My Ann Arbor System?

So every major installations goes through the decision making process on the solar panels. The crucial things are:

1. Output per dollar

2. Efficiency (If you have limited roof area)

3. How well they match with your inverter or charge controller

4. How well they are warranted

5. The company’s reputation

6. Appearance

7. Company ownership

8. Manufacturing location

9. Company philosophy

I had kind of decided on using Evergreen panels, but then I read that there is a significant concern about the company’s financial stability.

I’ve discovered that two of the major inverter & charge controller manufactures have great tools tools on their websites to help buyers decide what panels to buy and what solar panel configuration to use. Check out Sunnyboy and Xantrex/Schneider.

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Solar Design Tools

I spent about four hours looking at solar information again last night. There is a lot to learn.

On the Wind-Sun forum I also read about two scams. One that almost set the house on fire.

I also wanted to collect some links to some of the Solar Design tools I’m working with to get a better understanding for my system in Ann Arbor.

Let’s start:

A solar calculator:

Sharp’s “Clean Power Estimator:

A Good Celcius to Fahrenheit table and calculator:

A site for determining your solar panel string size:

More to come….

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More Progress on My Ann Arbor Solar Plan

I thought our plan to put solar panels on our roof was fairly complete. We were going to use
Enphase micro-inverters and just put as many as were practical up there.

But then two new points came up:

1. Electronic reliability is inversely proportional to temperature. And temperature change impacts reliability also. The roof of a house can see -20 degrees on the coldest day of the decade, then go up to 150+ on the warmest day of the decade. An an individual day could swing 60 degrees. That is not the best place to put dozens of inverters.

2. The wife wants some way to generate power with all that hardware up there even if the grid goes down. (There is no effective way to do this with the Enphase product.)

So we are back to a string tie system. Back to the drawing board….

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Solar Power – Innovative Way of Promoting the Future of Solar Power For Homes by Chris Hartley

San Francisco is the city where going green is developing into a lifestyle and is fast becoming a world leader in the use of solar power and is involved in a number of political and policy moves to promote the development of green technology. Together the Bay Area and San Francisco has come up with an innovative way of promoting the future of solar power for homes

Continue reading Solar Power – Innovative Way of Promoting the Future of Solar Power For Homes by Chris Hartley

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