Solar Photovoltaic Power

McDonald Solar and Wind Inc. can help you save money with Solar!

  • Solar power
  • Costs
  • Grid-tied battery-less systems
  • Grid-tied battery backed up system
  • Off grid systems
An 11.4kw Grid Tied Array - energy independence

"Solar power" is the use of the energy of the sun to "do work" (provide electricity or heat) for the collector of the energy. There are many ways to collect solar energy, including thermal collectors, photovoltaic panels, and solar concentrators. Most residential and commercial applications where the user wants to supply a significant amount of his/her energy usage from the sun use photovoltaic panels to convert the sun's energy to electricity.

If a user of solar energy just wants to eliminate a portion of his or her grid electricity usage, oftentimes they will invest in a solar thermal system to eliminate water heating or space heating costs. These systems are less of an investment in initial cost and do a lot to reduce energy costs in a household.

(Place your mouse on any underlined term for the definition)

Solar Photovoltaic (PV) systems trace their origins back to the early days of the Space Program. Even further back than that, the origins of the first PV cell were derived from the development of the first transistor back in the late 40's and early 50's. Early PV cells were extremely expensive to manufacture and build, and efficiency of the cells was not very good. Today, efficiencies approach 20% (sunlight energy in watts/ square meter to electrical power in watts/square meter) at the cell level and close to 16% for some panels. While this seems like poor efficiency, it represents tremendous progress in engineering and design. PV panels used to cost upwards of $1000 per watt in the early days of the space program. Now $2.50 per watt and better for bulk purchases is routine. We have come a long way.

So what do we use Photovoltaic panels and arrays for? Anything that requires a source of electrons; anything that you can plug into a wall, a car, or power with batteries or a AC converter can be powered by PV panels and arrays. ANYTHING!!

Do you have a remote well, need lighting in the middle of nowhere? Do you live off the beaten path? Do you need power for appliances, computers, signs, electric vehicles, lawn mowers, weed eaters? You name it and we can design and build you a way to power it; cheaply, reliably, and, once the initial cost is invested-- for FREE.

Costs:

Generally, once you get larger than a system size of approximately 2000 watts or more, system costs will run you about $4.00/watt (larger systems) to $10.00/watt (smaller off grid systems). Below that 2000 watt level, the lack of economies of scale make the system costs rise somewhat. Many factors will determine the final cost, including your site, energy needs, whether you will need to be connected to your local utility or be isolated and self-sufficient. A quick phone call to 719-330-2597 or an email to mcdonaldsolarwind@hotmail.com can get the process started. We have designed systems from 1000 watts (1 KW) to 500,000 watts (.5MW) so we can help you no matter how big or small your system is.

There are three main classes of systems used in household and commercial solar applications.

Grid-tied battery-less systems: A grid tied system is designed to "replace" grid-supplied electricity with electricity generated from the sun. If there are no batteries in the system, then the grid acts as the battery-- storing excess production over and above what the system owner needs for his own use-- in the form of an "energy credit" from the utility. You are selling your excess energy to the power company! If the user's PV energy production is less than what he or she needs at the moment, then the grid supplies the shortfall of energy, just as a battery would do.

One disadvantage of a battery-less system is that when the utility grid is down, the user has no source of electricity during the outage. To provide energy when the utility grid is down, you would need to install a grid-tied battery backed up system or a back up generator.

Grid-tied battery backed up system: A grid tied battery backed up system gives the user the added ability to power certain household or business loads during a power outage. The batteries become the source of power, and when converted to AC power by the inverter, the energy available can be used during a lack of grid power.

The battery and PV capacity must be sized to meet the expected energy need during a power outage for the user's critical loads. Inverter sizing is critical as well. One thing to remember in this type of system is that the home loads which are to be powered up during a utility grid failure are relocated to the inverter load panel, thus splitting your home’s loads into two segments; those that will be available during a power outage and those that will not be available.

Off grid systems: An off-grid system must supply all of its own energy. Because of this fact, careful consideration of household loads must be given. Any off grid system design starts with analyzing and minimizing energy usage in the home or business. After energy usage is minimized, careful attention must be paid to every aspect of the design. An off-grid design starts with sizing the battery bank to supply sufficient current for the loads it will supply while maximizing battery life. Sizing the Photovoltaic panel array is next to make sure that sufficient sun energy is available to charge the batteries. Sizing the PV panel capacity is a function of a "critical design month"; a month--usually a winter month-- when the sun is above the horizon for a minimal time and user energy is at a high level. The inverter needs to be carefully chosen as well to make sure that sufficient power is available to run loads simultaneously-- especially surge loads such as pumps and motors.