On this page, we discuss a few common scenarios and how they might influence your choice of solar collector or solar panel tilt angle (and system size).
Tilts that are focused on providing the amount of energy you need when you need it are often called "load tilts".
A "load" is just an energy need and can vary with time of day, time of the week, time of year, etc. - for example, if you generally use 30 kWh of electricity in the summer but only 25 kWh in the spring, then your electrical load is higher in the summer than the winter.
The "optimal tilt angle" for your photovoltaic or solar hot water system is the tilt that is best for your situation. In general, when deciding how to tilt their solar panels or solar collectors and how to size their system, people need to think about how much energy they need and when they need it as well as financial and technical constraints specific to their project.
Solar hot water systems are often given a "winter tilt" - that is a tilt that is angled to maximize the amount of winter sunlight gathered.
This makes sense because it doesn't cost all that much more to make a solar hot water system larger and so it is often most economical to angle the collectors so that they get the most possible sunlight in the winter but size the system so it comes close to meeting all of your summer solar hot water needs. In this way you can maximize the amount of insolation gathered each day.
On the other hand, the high cost of photovoltaic panels often makes it more practical to angle them in such a way that optimizes year-round production (optimal annual tilt). This means that you have to purchase more energy from traditional sources during the less-sunny times of year but over the course of the whole year you gather a lot of solar energy per square foot of solar panel.
Your PV tilting decisions are often influenced by your relationship to the electrical grid. If you rely solely on your photovoltaic system to provide all of your electricity ("stand-alone system" - generally with a battery), you will have to give priority to making sure that your daily minimal needs are met.
In this case it might make sense to for example choose a winter tilt so that you meet your minimum electrical needs during the periods with the lowest insolation. Of course, other variables can change things. For example, you might not need any electricity in the winter (maybe you spend your winters away, etc).
Often, you can purchase electricity from an electrical grid ("grid tied") but can't sell any back to the grid. In this classic grid-tied case, you will probably want to tilt and size your system so that it provides a decent percentage of your annual electrical needs but doesn't ever (or very rarely) produce more electricity than you need.
You could do this by investigating different system sizes and tilt angle configurations and seeing how much electricity they would produce annually while also paying attention to how much would be produced on an average day during the sunniest months (keeping in mind that some days it will be sunnier than the average day). Additionally, it would be sensible to keep any low-usage times in mind (do you spend your summers away, etc) as well.
If your electrical grid buys back electricity and you are confident that it will continue to do so for a long time, you would probably worry less about exceeding your energy needs on very sunny or low-usage days.
We compare some common methods for choosing an optimal annual tilt at optimal tilt.
On tilt deviation we examine how much energy is lost if your tilt angle is lower, higher or to the East or West of the optimal annual tilt angle. And on that page we even look at how much extra energy you could expect to gain by adjusting your tilt seasonally.
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