If your current electric bills are off-the-roof then you’re probably wondering if solar is a good alternative energy source to consider.   And, if solar is a consideration for you, then you should know some key factors to determine what’s right for you.  In this discussion, we’re simply going to focus on one factor: properly sizing your solar power system for your needs today and in the future. 

In most cases, the solar consideration and ultimate goal for everyone to go solar is often to simply “zero out” or “offset” the electric bills at 100%.  And to determine the size of a system to meet this task, installers usually take your last 12-months of electric bills and add up the monthly kWh usage to recommend a system size that will produce the same amount of electricity for that year.  That way you neither owe money or gain, in the form of credit from the utility company, when the “true-up” (also called settlement bill) arrives at the end of a one-year cycle.

So, is 100% offset the correct size system to obtain when you’re out shopping for solar?  Before you say, “Yes,” we at Solar Power Supply suggest you think about the future.  What we mean is that you should consider “future-proofing” your system to a certain degree at a size bigger than 100% offset.  Ask yourself what lifestyle change(s) can, may, or will happen for you in the near future that can impact your energy usage. 

For instance, is there a future electric vehicle (EV) purchase?  An addition to your property such as a pool, spa, ADU expansion, etc.? A change like more people working from home, additional family members moving in, a newborn, or elderly that will be a part of the household?

Answering these questions will greatly help determine the true size you’ll need for many years to come because these all affect your lifestyle and will certainly add more to your energy consumption.  Provisioning for such changes will seriously help to future-proof your system. 

If a purchase of an EV is on the horizon, know that it takes an average of 3,700 kWh per year to charge one at home, and of course it will differ based on brand and model.  You can somewhat offset future charging by adding a good percentage, say 25%, to the size of the solar system you’re shopping for, or fully offset an EVs electricity demand by adding its kWh energy yearly usage to the solar system.  Adding a pool to a home and using a pool pump to circulate the water adds between 3,000-5,000 kWh per year according to a study by the U.S. Department of Energy.  

And, if you expect a change in household or simply having more of your family members home more often like working from home, know that there will be a significant increase in energy usage. With more people at home, lights are turned on more frequently in restrooms and closets, refrigerators are opened more times than normal, usage of appliances like electric ovens, microwaves, and toasters rises considerably, and there’s an intensified increase in running the HVAC to manage the entire home’s temperature to a comfortable living level.  According to PickHvac, the average central air conditioner uses around 2,475 kWh per year, and with more people at home, that kWh usage can quickly escalate. 

It’s quite often experienced by current solar owners to wonder why they owe money at the settlement period when they have a perfectly working solar energy system.  They’ve quickly forgotten about those “significant lifestyle changes” that weren’t considered pre-solar purchase, often shifting blame that their solar panels are not working or the technology is a sham because it’s not producing the energy to cover their consumption level. Keeping in mind changes in lifestyle and prepping for them is an essential part of the solar shopping process.

Another consideration for future-proofing is power output depreciation of a solar energy system.  The highest energy output of any system will occur in the first year of installation.  Like anything you purchase, whether it’s a car or an appliance or any technology for that matter, its best performance occurs at the beginning when they are new and tapers down as they get older.  Same with a solar system with panel performance decreasing in output by a very small margin at an average of .5%, called degradation rate.  Although minor, it does have some effect in the offset decision making. 

For example, if you’re offsetting your average usage of 10,000 kWh per year, and you have a solar system that produces 10,000 kWh for the first year (100% offset), the next year it will produce 9,950 kWh (.5% less), and the third year at 9,900 kWh, and so on. As you can see, the decline will no longer cover that 10,000 kWh usage as the system gets older. A larger size solar system will compensate for the degradation rate to produce above that particular usage.

The effects of weather are also something to be considered with a solar power system.  Because we can’t predict the weather, know that output performance can vary.  Energy production is at a minimum when it’s cloudy and during rainy seasons and less on months with shorter days like in the winter.  Even extreme heat has an effect on performance on days when temperatures are beyond 100 degrees.  Energy output slightly declines with all solar panels when it passes its temperature tolerance at a percentage dependent on the solar panel’s coefficient rating.  

Recognize that solar panels produce power by converting sunlight it receives, not heat! With a future-proof-sized system, sunny and longer California days like in summertime will more than make up for lower output on bad weather days. 

Setting expectations and knowing key factors gives you a better experience with solar ownership. So, when sizing a system, if budget permits, a bigger size is encouraged for future-proofing.  Give yourself a cushion with an offset size of a system of at least 10%-15% more.  The increased size will definitely help on unexpected and expected slightly higher energy usage from the norm such as during longer summers, hotter days and lengthier family visits when air conditioning systems have to be kept on for longer periods of time.  Oversizing a system is a sure way that you will produce more power, and more of the excess will be sent to the grid to establish a higher bank of credit that you will use for nights and bad weather.  Ultimately, it’ll be great to possibly get a nice credit for the energy overage or to not owe the utility company at settlement time at the end of the cycle year.  

One last thing to note is that expanding to an existing solar system can be quite expensive. Most people consider the thought of, “I’ll just add several more panels later on and get only what I need for now” but, unfortunately, this mindset gets pricier and the process takes just as long as when a system was first installed.  Plus, the 30% federal tax credit incentive can’t be claimed for future solar panel additions because it only applies on the original purchase.  The only exception is with the addition of a backup battery.Now that you’re more informed about future-proofing a solar system, call us at 951.338.8060 for one of our staff members to help you properly size a system that you will truly be happy with. 

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