Off grid solar PV systems have battery storage and are not connected to the utility grid. They generally also have a backup generator to charge the batteries in times when the solar PV system is either not producing any electricity or not producing enough to keep the batteries in a good state of charge.
Net metering allows a producer of electricity to “store” any excess electricity generated by their solar array, beyond their immediate needs, in the utility grid for later use. Unlike a feed-in tariff (FIT), which requires two meters, net metering uses a single, bi-directional meter that can measure current flowing in two directions. BC Hydro allows net metering for both residential and business customers. Any excess electricity “sold” to the utility is “bought” back from the utility at the equivalent rate per kWh at the time the “transaction” is made. When you sell to BC Hydro, you get a bill credit towards your future electricity use. If you still have an excess credit at your anniversary date of joining the program, they will pay (or credit) you for the electricity at the rate of 9.99 cents per kilowatt hour (kWh).
Since net metering requires a direct connection to the grid, unless special provisions have been made, your system will not generate any electricity in the event of a power outage in your area.
Grid tie installations are generally much less complex that off grid type systems as they do not require any battery storage. The simplest grid tie systems involve the use of what are termed micro-inverters. In micro-inverter systems, each solar module has it own inverter, which converts the DC power generated by the module directly into AC power to be used in your home. Because of this, all of the add-on wiring required in a micro-inverter system is of the same type as the other AC wiring used in your home. This makes it much less complex than the add-on wiring used in a string inverter system, which must be DC compatible.
Grid tie systems will not generally generate power during an outage, however, grid tie systems with battery backup can be configured to generate power regardless of grid power status.
Given the money and the space, solar PV systems are expandable. The ease at which this can be accomplished depends on the type of system (micro-inverters or string inverter) and what provisions have been made in advance. For example, with a string inverter system, additional solar modules can be readily added only up to the capacity of the string inverter and only up to the capacity of the wiring. With micro-inverters, the inverter does not present a limit to expansion, as the inverter is added with the module, however, the capacity of the wiring is also a limiting factor respecting ease of expansion. Hence if expansion is anticipated, it is generally worthwhile to keep this in mind when considering what size of wiring to be used in the initial installation.
A conventional or string inverter system has a central inverter which converts the direct current (DC) produced by the solar modules into alternating current (AC) which can be used in your home. A microinverter system has a single much smaller inverter for each solar module. At one time string inverter systems were usually less expensive that micro inverter systems but this is no longer the case. Micro inverter systems have the advantage of being simpler over all, because of the no DC wiring, safer to install and easier to expand. This means that unlike a string inverter system, if one panel is faulty or shaded or otherwise not performing at optimum, the performance of the other modules is not compromised (as is the case with the string inverter system). Micro inverters also allow for easier identification of faulty modules.
For rooftop solarPV installations the type of roofing material is not of much significance, as the technology exists to safely attach solar panels to almost any type of roofing. If your roofing material is close to the end of its service life, however, you may want to consider replacing the roofing material before installing your solar PV system. Standing seam metal roofing is a good choice in this case, as the solar modules can be secured to the roof without having to penetrate the roofing membrane.
In 2017 the Residential Conservation Rate, BC Hydro customers pay 9.5 cents per kWh (including rate rider and GST) for the first 1,350 kWh they use over an average two-month billing period. Above that amount, customers pay 14.2 cents per kWh (including rate rider and GST) for the balance of the electricity used during the billing period.
Sustainable, economically responsible, non-polluting energy is the only way to secure the future of our environment and our well-being. Solar panels generate zero pollution. With a GabEnergy custom designed solar system, you can be saving money on your energy bills while helping improve the environment. You can begin saving money on electricity immediately and with electricity rates likely to rise in the future, your savings will continue to grow. Besides saving money, solar can be a good investment for other more personal reasons. For some, simply wanting to contribute to a renewable energy future or to become more energy self sufficient, makes solar PV a good investment.
Determining the payback on an investment in a solar photovoltaic (PV) system depends on a number of variables: cost of the installation, electric utility rates, size and location of the solar array and hence annual electricity production, rebates (if any), financing costs (if any),, and future inflation rates. In British Columbia where currently there is no feed-in tariff (rate above retail electricity rate paid for production), the payback for solar PV is not as good as Ontario where a feed-in tariff exists.
An alternative to a payback model is an industry standard known as your levelized cost of electricity (LCOE). This is simply your average cost of electricity as calculated over the lifetime of the system. Think of this as pre-buying your electricity that fixes your electricity rate for more than 25 years.
Feel free to contact a GabEnergy representative for further discussion on this matter.
Costs for a solar PV system have dropped dramatically in the last 5 years or so. Costs depend on system size (generally smaller systems are more expensive per unit of power generated), location (rooftop versus ground mount) and complexity of the system. At GES we strive to bring our customers the highest quality systems at the lowest cost. Costs so far have ranged from a low of about $2.25 per watt installed DC, for DIY systems to a high of about $3.50 per watt.
The power generated by a solar PV array depends on the number and the capacity of the solar modules selected and the location and orientation of the system. The capacity of the modules generally range from 250 watts DC to 350 watts or more.
In most parts of the province it is possible to generate about 1100 kWh per year per kilowatt DC of installed capacity from a fairly open site. This means that to offset the annual power consumption of a typical home in the province of 11,000 kWh, would require a 10 kilowatt DC system.
In order to eliminate your electricity bills you must generate at least a much electricity from a solar PV system as you consume on an annual basis (actually slightly more as the utility provider has a fixed monthly usage charge). For the average household in BC this would require at least a 10 kW DC system (for example 40 panels of 250 watts). Your annual consumption can be determined from your BC Hydro (or whichever is your electricity provider) bills. We usually recommend considering electricity savings measures, from the very simple, such as turning down the thermostat and closing off unused spaces to others such as energy saving appliances, LED lighting, weatherstripping, heat pump (if you use electric resistance heating) etc., before deciding on the size of solar PV system to select. Your GabEnergy representative can provide you with the guidance you need to determine which size system is right for you.
Solar panels/modules generally last at least 25 to 30 years and are backed both by a warranty and a performance guarantee. Most manufacturers warranty their modules for 10-12 years and guarantee their performance to be within 80-90% for 25 years.
If you are building a new home and may want to add a solar PV system at a later date the most important consideration is system location. You will want to locate and orientate your system to maximize performance. This in general requires a more or less southern orientation, which has minimal shading especially from late winter to early fall.
If a ground mount is most suitable and desirable then you need to consider the size and location of the ground mount as well as how the wiring will run from your ground mount location to your house and ultimately connect to your home electrical panel. You may also want to consider installing the underground portion of the wiring before installing concrete patios, trees or shrubbery for example.
If on the other hand, the system is to be roof mounted, then more must be considered. For example, the slope, orientation of the roof and roofing material chosen, all can have considerable impact on ease, effectiveness and cost of installation. Ideally, the house roof will have at lease a section oriented more or less solar south, of a size suitable for the size of system that you may want. You may also want to consider having a roof slope that is steep enough to provide for good solar production but not too steep as to make installation more challenging. Respecting roofing material, standing seam metal roofs for example, do not require penetration of the roof membrane for module installation, so this may also be a consideration. Consideration should also be given to providing the wiring to the roof to accommodate the anticipated size of the system or providing a wiring chase for ease of wiring at a later date.