Good afternoon,
I just wanted to say thanks for dropping into to read this and comment if you have, and I wanted to say that these posts will be going up more regularly (dog-sitting, camping, et al. have taken a toll). To recap the previous post in a few words; contracts- they impact how you go forward with your project and determine how you can cancel your project. Okay, now that the recap is done, we will move forward with our discussion of design elements, components, and briefly discuss net energy metering (NEM). So as in real-estate, location (of the property), location (of the panels on the roof), and location (for permitting reasons), are the key elements to solar design. However, before we begin, we need to discuss roofing materials as that is what your system will be installed on. Most solar firms will install on any asphalt shingle and be able to coordinate with a roofing company to do flat roofs with foam, tar and gravel, or membrane roof. However, if your roof material is Terra Cota, stone tile, or shake shingle, then most firms will not install or even bid on your project as they will consider that there is no roof access without breaking tiles. The first location to be discussed, is the location of the property, as in, where is it and what obstructions are around it. Your property should have a clear and unobstructed view of the sky with no shading coming across the roof during the day or a minimal amount. If your roof is shaded by trees, ridges, or other buildings so that the roof of your building is in the shade most of the day, solar may not be an appropriate solution for you. Solar panels as right now have an efficiency rating of 19% to 22% for tier 1 panels, so the amount of actual sunlight that hits your roof and/or property is incredibly important to factor in when designing a system. As a sidenote, I am based out of the Northern Hemisphere, in California, so all designs will have a southern facing bias. Systems in my area, in an ideal situation would have a true south orientation with a few degrees tilt to be able to capture most of the days production. However, that is not always possible, so you may have to make trade-offs on where to locate an array on your roof or property. For designing in California, we also must consider Net Energy Metering, which is the generally policy for stating what the exchange rate is between solar producers (non-utility producers) and utilities. In my area, there are also different Times-Of-Use (TOUs), which further impact panel layout as the cost of electricity ranges from 17cents to 47cents per kWh depending on the time of day, so you want to produce as much in the higher tiers as possible. Panels are going to go on your roof, or your property, so let’s talk about them next.
Where do panels go on your roof, or property? To answer simply, it depends on where the most production occurs throughout the day, and where it is possible to install. Firms, in general will not install single panel arrays, as it impacts the mounting process, and large single planes will get the best production as you can have one large single array. Additionally, panels sizes vary by manufacturer and model, so depending on the panel used in the design, different locations may be used and different mounting types as well (tilt-up or flush). However, most panels are around 170 x 101.6 x 4 cm (LG) to 164.4 cm x 120.4 cm x 4 cm (Solaria), again this is general range for dimensions to keep in mind. All right, the next location to be discussed, is your permitting jurisdiction. If you are installing solar, you will need a permit, and that can range from $0 to like $700 depending on what you are doing. Your contractor will be including that as part of their bid, but do make sure it is spelled out in your agreement with them. To receive a permit the design of the system may have to meet some stipulations, such as, leaving emergency roof access, and not covering up any protrusions in your roof like exhaust vents, pipes, skylights, or sky-tunnels, also that the panels do not hang-over the roof. These are some general elements for solar design, and they may change and are not exhaustive or exclusive. I have also included an image here for the setbacks that were discussed.
Now, that we have covered general design concepts, let’s talk about the fun stuff now, the gadgets that produce electricity out the sky. Your photovoltaic system is going to be comprised of two main components, the panels, and the inverter(s). Now, there are numerous companies out there that make wonderful panels, however, we will not be reviewing them here today unfortunately. I have provided some information about popular brands that I have sold in the past and their technical specifications in the resources section of the site. From the large brands that we supported, I can say that the power of the products almost doubled in a three period when I was working with a local installer and the costs decreased slightly on a price per watt basis. The value though of the panels becoming more powerful in the top tier products is what sold the systems because there were less panels and systems had a higher potential of being full off-set systems (meaning producing the same amount as the property was consuming) with a short (7 years or less ROI) return on investment. Now with current generation solar panels, most homes can have a dramatic reduction in their overall energy bill if they have solar access. Additionally, the value of going solar is also becoming more worthwhile because it appears that there is a large move to more electrification of products. Panel technology is advancing, and stock availability does change, so make sure your contractor has a supply of the panel you have selected, or you have discussed what would happen if a panel were unavailable. The other major component for your system is the inverter or inverters depending on the design of your PV system.
The inverter is a component that converts the direct current that is produced by the panels to alternating current that runs in your home. Now there are a couple of inverter technologies, the first inverters were the string inverters that have a single inverter, and all the panels work on the same circuit or on strings. The updated version of these systems are the optimized string inverters that have an additional component that can isolate the loss of a panel from impacting the single inverter, however, there is still a single inverter that can cause a central point of failure. The newest version of inverters are micro-inverters that operate with a parallel design feature and without a central failure point. For micro-inverters, each panel has a small “micro” inverter that converts the DC electricity to AC electricity. The AC electricity is then channeled to your home through a combiner box. The firm that I was at most recently, and our competition had been moving to a micro-inverter design solution due to maintenance and AC- Coupled battery availability. For solar projects, batteries have become a more popular inquiry however, they dramatically increase the return of investment on solar projects (they at least double it). Batteries, and what they offer are two different things that can maybe they should be priced differently by the property owner, as one offer is economical -through power arbitrage, and the other emotional, as protection from a major outage. As a product for power-arbitrage, batteries are currently expensive when it comes to pay-off especially when compared to solar production; a non-Tesla installed battery system runs from around $15,000 for a 13.2kWh battery system on up depending on other factors. Currently, it the pay-off is better for building a solar larger system, if possible, rather than adding a battery, also to get the best return going the power-arbitrage route you have to be using a substantial amount of electricity each month and each day with a Time of Use system that has different costs during the day. The other reason for getting a battery, is to have insurance in-case of an emergency or outage, and that value is harder to evaluate and each property owner will have a different budget for that. However, if you are considering a battery, please remember that they are the only way to currently create a micro-grid that stays up during an outage. IF you have solar only, you will also be participating in the outage with your neighbors. Alright that was a dense piece that covered the basics of solar design, and what components are used for solar projects, and I in the next article I will discuss Net Energy Metering, TOUs and regulators in CA and how they impact your, or at least try to. Until later take care and be well.
Best,
Piotr