Working with kits

Some manufacturers offer complete kits for solar PV systems. If you’re going

to install yourself, there are some big advantages in using kits.

 ✓ The design has been worked out, and it’s going to operate the way it’s

supposed to (given that you mount and connect the equipment prop-

erly). PV system design is very complicated, particularly optimizing PV

panel strings that feed the inverter. With a kit, the optimization has been

done for you.

 ✓ You’ll get all the parts that you need and they’ll work well together.

When you’re finished with your masterpiece and there are parts left

over, you’ll know you didn’t do something that you should have done.

 ✓ When you design and install your own system, and it’s not working up

to par when you finish, the manufacturers of the individual components

are often reluctant to honor warranties. When you use a kit, the war-

ranty terms are spelled out precisely; basically the only requirement is

that you install the system properly, which is easy enough to prove by a

simple visit to the site.

 ✓ With most kits, a customer service number is provided so that when you

run into problems an expert can help you through the mess. Terms vary,

so understand what kind of support you’ll get and whether you have to

pay. Typically, there is a time limit to how much they’ll provide for free,

after which point you have to pay an hourly rate.

 ✓ The price of a kit is very attractive, compared to buying separate com-

ponents from separate manufacturers.

 ✓ Assembly instructions are well written and concise (they better be, or

they won’t sell many kits). They take you through every step of the pro-

cess and they spell out the dangers and potential problems.Safety

Above all else, you want your system to be safe. PV systems generate all

kinds of dangerous voltages, not to mention the physical dangers inherent

in climbing around on roofs and using power tools if you do the installation

yourself.

PV panels are dangerous even when they’re not connected to anything. The

two wires from a PV panel are “hot” whenever sunlight shines on the panels. If

you wire a number of panels up in series, the voltages can exceed hundreds of

volts, which can literally kill you. If you have turned your PV system off, that

does not mean it is safe. Any sunlight striking the panels can generate enough

oomph to cause major shocks. I repeat: If utility power is shut off, and you have

turned the PV switches off, your system is still dangerous! Do not open the switch

junction boxes, nor the inverter. Let a pro do the work; they know what’s safe

and what isn’t.

The best bet, from a safety standpoint, is to understand exactly what you’re

doing at all times. With many projects, you can learn as you go. Not so with

PV; understand the entire process well before you go.

Following are some general guidelines for ensuring a safe installation:

 ✓ Be alert at all times. The fact is, most accidents occur when people

are daydreaming. Drink your coffee before you begin work, and don’t

be talking on your cell-phone while you’re messing around with your

system.

 ✓ If possible, never work alone.

 ✓ Use good quality tools, in proper working order. Cheap tools are not

cheap and wear the appropriate safety gear:

• A safety helmet when you climb around on a roof.

• Eye protection at all times

• Dry leather gloves whenever possible (sometimes you have to take

the gloves off because you just can’t achieve enough manual dex-

terity with gloves on).

 ✓ Always assume that switches are turned on, and never assume that a

switch is working properly. Sometimes switches in the off position aren’t

off. Never assume your system is safe, even if it’s supposed to be.

 ✓ Understand the principles of grounding. The purpose of grounding is to

prevent unwanted currents flowing through people or equipment that

they’re not supposed to flow through. If you’re not properly grounded,

you can be killed if something goes wrong.Exploiting every bit of energy

your system generates

Here’s the simple reason why intertie is so important from a financial angle:

You exploit every ounce of the energy that your system generates. To under-

stand this point, consider a solar hot water heater (refer to Chapter 12). When

you go on vacation for two weeks, the equipment sits idle: It’s not paying

you back one single dime. With intertie, you benefit from every photon that

strikes your system. You get the most bang for the buck for that expensive

equipment you’re investing in. When you go on vacation, the solar PV system

is subsidizing your vacation.

Intertie is such an important concept that state and federal governments are

legislating that utility companies must allow their solar-producing customers

to tie in to their grids. Utility companies, for their part, don’t necessarily want

these types of customers; their technical risk increases, and their revenues

decrease. Plus solar PV entails more equipment and more complex power

meters (conventional meters aren’t calibrated to spin backward). When you

install a solar PV system, the utility will probably have to change your meter

and, in many localities, it can’t charge you for the new meter.

 Most intertie systems won’t work when the grid is down. This concept is coun-

terintuitive: You install your own power production equipment, so you should

be able to have power regardless. But the fact is, the utilities don’t want you

putting power into the grid when the grid is down because it endangers line

workers and may actually destroy transformers and other power equipment.

The safest and best way to eliminate this risk is to require that PV intertie pro-

ducers use equipment that won’t operate when the grid is down. Although you

can purchase PV system that will work during a power outage, these systems

there are more expensive and probably not worth the extra cost.