• Solar Expert

Buyers Guide: What is a "Residential Solar Panel System"?

This is about hard facts and industry examples of what a residential solar panel system is, how they work, and what solar panels are best for Montana in the valleys as well as higher elevations. And why you should be taking a hard look at solar for your home, or even your home based business.

A residential solar panel system, is simply a solar panel system that is specifically designed for application on residential property that matches the utilities grid power frequency and voltage. If you are in the USA, the utility grid uses 60hz for a frequency, and in almost every case your voltage is 120/240V AC nominally, or you may also hear others call it 110/220V, and that is the same, but taken using a different scale to measure the voltage.


Now, there are some differences in solar technology that can make a system perform better on a residential project starting with:


Solar Panels

There is no real "residential grade" solar panel. There are different types of cells and with out getting into the nitty gritty of N-Type or P-Type (one has an additional negative electron, the other positive electron in relation to the silicon), there are Poly-crystalline and Mono-crystalline modules.


Mono-crystalline modules have a slight energy production edge over Poly-crystalline, however they are also known to have a 1st year fall off of production that after that period are similar in production to Poly modules (panels). So they really are pretty equal, however, as I type this, most modules being sold in Q1 of 2020 are Mono, mainly because of the solar panel wattage that sells better at 320-330 Watts each. Most of the Poly's are around the 300-310 range in the same size. There are some higher end modules on the market that are producing around 360-370 watts each, but those are costing 2X the standard modules today.


Another factor in solar panels is there size. The industry has standardized two sizes, 60-cell and 72-cell. The sizes simply indicate the cell count based on full sized cells, both modules have a nominal width dimension of 39", where the 60-cell is nominally 65" high where the 72-cell is nominally 77" high. The 60-cell is almost exclusively used in residential for the only reasons, that they configure better on roofs and are much easier for installers to handle when running around on steeper roofs.


When looking at types of cells, module wattage size is not much different between modules, and 60 and 72-cell modules have the same cells in them. When comparing 60 and 72 cell modules, build quality is the same, and production of the modules are equal when looking at it from a wattage per sq ft, ignoring of course the small factor of the frames of the modules.


Inverters

The inverter is the part of the solar system that is responsible for taking the direct current produced by the solar panels and converting (inverting technically) to the useful alternating current coursing through all your wires at your home. There are several different types of inverters, like:


Off-grid inverters- These inverters are designed to have no interaction with the power companies grid and require a battery system to store power produced by the solar panels or a optional additional source, such as a generator (most common), wind, hydro, etc. These types of systems are generally used when a site is either too expensive to get power lines to the site or not practical. For more information Click Here.


Hybrid grid-tie inverters- A hybrid grid tie inverter will encompass some of the technology of a off-grid inverter and a grid-tie inverter. These are becoming more popular with sites that in need of power backup situations or where the utility has time of day billing. These inverters usually allow for the system to be programmed to the flexibility of demands of the site, such as us battery power before grid power during an expensive utility grid power time, such as 5-9 PM. Or even sell power back to the grid during these times. For more information Click Here.


Standard grid-tie string inverters- With this type of inverter the solar system is directly connected to the power grid and the grid is used as a sort of, unlimited battery. You either consume a all, none, or a portion of your solar generation. Anything you do not use at that given time is then being exported to the utility lines via a "Interconnection Agreement". Most often, any exported energy is credited to you, by the utility at the rate in which they bill you. Some utilities pay a higher rate for your exported energy in exchange for your Solar Renewable Energy Credits that help them meet their mandated clean energy portfolio. For more information Click Here.


Grid-tie String inverters with optimizers- These inverters are the same as a standard grid-tie string inverters with the added benefit of a optimizer. The optimizer allows for each solar panel to produce the maximum amount of power each without other modules limited each panels potential, which is what happens with a standard grid-tie inverter. The optimizers also allow for module level monitoring, so with monitoring, you can login anywhere and see how much power each module is producing, something a standard system isn't capable of. Optimizers ultimately maximize production and offer added monitoring benefits. These are often a little more expensive than a standard system, but quickly pay for the difference in price with better performance, plus they offer direct connection to battery backup systems and integrated Electric Vehicle charging (currently on some models). For more information Click Here.


Grid-tie micro-inverters- Micro-inverters have the benefits of the string inverters with optimizers, and an additional added benefit of being a little faster to install for the installation team. The downfall to micro-inverters is they are installed on the roof. Exposing 300+ electronic parts per panel to the elements. While optimizers are also exposed to this environment, the parts exposed are approximately half of the parts in a micro-inverter. Micro inverters also have some limitations on the future additions of battery back-ups or Electric Vehicle charging integrated into the Solar system.


Unless you are off the grid, installers will suggest all different types of grid-tie inverters in their designs. So to sort through some of the confusing information and marketing pitches, i've put together my short timeline and experience with most of these inverters.


With over 15 years in the industry, I have seen all of these types of inverters come to market, some survive, others do not. I was always highly suspect to the “new“ inverter technology types on the market and the way I saw it, more features means more potential problems. After our analysis of most of the mainstream products on the market, and after analysing only product with a fair amount of time on the market, the best grid tied inverters on the market from a performance and durability standpoint, turned out to be an optimizer based string inverter made by SolarEdge™. When they first came onto the main market I was leery as to adding electronics to a hot roof and under each module, think of all the potential failure points being added (186 to be exact) added to each solar panel from the optimizer. The same went with micro-inverters which are approximately 356 components added under each solar panel in a widely varying temperature and humidity environment on the roof or in the yard.


SolarEdge™ Inverters

After having seen some of the competition selling these systems for all the glamorous

features they have, and that a standard string inverter doesn’t, we started to ask questions. Why aren't we selling Optimizer based systems? After the product from SolarEdge™ was run through its real life paces over time, they started designing and installing robust components within the optimizers that were in-cased in resin for protection from the environment. The electronics where ceramic based, vs. the original lower quality electronics, that are still used in some of the top named micro-inverters and came backed by a warranty longer than the inverter itself.


We chalked up (literally, we wrote it on the chalkboard) the pros and cons of each type of inverters, and at the end we were asking ourselves, why are we not selling SolarEdge™ optimizer systems?! And from that day on, we haven’t looked back, and we have hundreds of satisfied solar customers using optimizer based string inverters from SolarEdge™ and many have tried to compete and they just haven't gained the traction. On top of the technical reasons we like them, there company is financially strong and one of the highest recommended solar energy company stocks by top investors. Plus, they are out front of other companies on innovation with systems that are battery backup ready and some models have integrated Electric Vehicle Chargers, and because of the integration are eligible for the Federal Tax Credit (26% in 2020).



Batteries

The most common questions people have asked over the years is- Where do the batteries go? Most systems (95%), as described in the inverter section, are grid-tie with no batteries. However, the industry is now seeing a transition in some markets to implement batteries for some backup and/or peak shaving and special time of use charges from the utility. In some markets these batteries make a lot of sense to design into the system, and often batteries can be designed into the system at a later date. Some of the systems on the market are not as "battery ready" as others, but in most cases the system can be configured to encompass batteries for backup, load shedding, or for future off-grid situations.


Backup

Systems that have batteries for small emergency backups to get you through a day or less, without grid power, typically use an all-in-one battery system like an LG Chem™ RESU 10kWh battery system or a Tesla™ PowerWall™. These are good for markets with time of day utility billing.



If long-term backup is necessary, then a much larger system is required and must be custom designed. These types of systems could also be incorporated into an off-grid system, but is not that common.


Off-Grid Battery System

A conversation with a residential solar expert, would be able to identify if batteries are a good option for your situation or not. Some times, a generator is the best solution for emergency situations and sometimes a battery backup is the way to go. It all comes down to the economics and site preferences. Talk to an solar expert.


Monitoring

Without solar monitoring, you have no way of knowing how your residential system is doing. And if something does go wrong you will know weeks before you would with a system without it. Plus, there is something really cool about watching something you own produce your own electricity.


With systems that have panel level monitoring you can see what each panel is producing and how the weather impacts that production. With some of the residential systems the monitoring can also identify what your home is using for electricity, giving you the power to turn into the "energy police" of the household. Sorry in advance.


With the real time monitoring, you can no longer be surprised monthly with your electric bill on what you have been using for electricity, now you can become proactive and takes steps to conserve your energy as well as producing it.


To Buy or Not to Buy

Solar isn't for everyone, but it should be. It saves you money and with financing, there is no reason not too. It improves your home value, something the status quo with the utility isn't doing for you. Buying your electricity from the utility will cost you thousands more in energy costs over the next 10-30 years, it is like buying a house vs renting one. You're renting your electricity from the utility now.


Solar has been around for decades and has come a long way in cost and technological advances. Waiting for it to get better, is no longer a viable answer in not going solar, it's here and incentives are going away. Find out today what your cost of doing nothing is costing you. See if you qualify for cost effective solar---> here or fill out a analysis request below to see if you qualify.



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