There is a lot of information out there about solar electricity systems. At times this information can seem very complex and confusing. We here at Revco Solar Engineering have created The Fair Buyer's Guide to help you navigate the process of choosing the right System for your needs. The Fair Buyer's Guide covers what you should know before buying a Solar Electricity System.

System Power

The power of a Solar Electricity or PV system is specified in “Watt”. Here is the trap: There is the power generated in the PV panels, called “Watt DC” and there is the power of the complete PV system that is used to power all your devices connected to 110 Volt outlets, called “Watt AC”. The power that offsets your electricity bill is Watt AC, not Watt DC. Don’t let anybody fool you with a big Watt DC number.

Performance Calculation

The performance calculation for the Solar Electricity or PV system, which should be done by solar engineers, makes you a happy or not that happy PV system owner. Why? Before purchasing a PV system you want to know how much power your future PV system will generate so that you can predict your savings. In fact, the performance calculation has to be accurate!

You may want to ask your supplier a few specific questions:

• Have you considered conversion losses (DC to AC)?
• Have you considered conversion losses (DC to AC)?
• Have you considered wire losses?
• Have you considered the loss caused by dirt and dust?
• Have you considered orientation and tilt?
• Have you considered specific sun radiation at this location?
• Have you considered temperature?

Don’t worry; you don’t have to understand the underlying technique. Just insist that your supplier will take all of the above into consideration when calculating the predicted power generation. Otherwise, the damage will be in your hands not the supplier’s.

Performance Guarantee

As described in above “Performance Calculation” you are very dependent on a good engineering work from your supplier without being able to verify if he did a good job. Is this fair? Why not ask your supplier to guarantee that the PV system will generate the power that he predicted?

System Warranty

Every PV system has to come with a 5 years workmanship and material warranty; otherwise the PV system is not entitled to the State rebate. All installers are willing to sign such a warranty. However, it may be a good idea to ensure that the installer’s company is well insured and stable enough to deliver the warranty service over the next 5 years if required.

Product Warranty

Product warranties are given by manufacturers. You should get 25 years on the PV panels and 5 years on the inverter.

Solar Right

You can get solar energy systems in spite of what you Home Owner Association told you.

Every property owner is entitled to install solar energy systems. California law invalidates and renders unenforceable any instruments affecting the installations or use of solar energy systems. However, the law allows provisions that impose “reasonable restriction”, defined as increase in cost or decrease in performance up to 20%.

Lifetime Expectations

The expected lifetime for solar panels is 45 to 55 years, for inverters 15 to 20 years. If you got a long term financial analysis for your system, it is a good idea to ask your supplier if he considered the maintenance cost for the inverter.

All those strange names and abbreviations!

Why can’t the solar guys speak in plain English?

The following will assist you in understanding the information you need in making a good decision:

AC or Alternating Current

The electricity delivered to your house is AC. The direction of electrical current reverses, usually many (60) times per second. Electricity transmission networks use AC because voltage can be controlled with relative ease.

DC or Direct Current

A one way flow of electric current. Typical sources of direct currents are electric cells, rectified power units and direct current generators. This is the current flow produced by a solar system. To be used for typical 120 volt or 220 volt household appliances, it must be converted to AC.

Grid

Transmission line network used to distribute electric power.

kW or Kilowatt

1000 Watts

kWh or Kilowatt-Hour

Unit of energy used to perform work (energy and work are equivalent in units, energy being the potential value and work the achieved value).

Photovoltaic or PV or Solar Electricity

Photovoltaic or Solar Electricity is the phenomenon that light is directly converted to electric power in a material that is known as “semiconductor”; the same material used in your computer chips. (see also “How solar electricity works”)

Watt

Unit of power. Power is the rate of using energy to do work.