With this we mean how much electricity you will, realistically, produce through the year. There are multiple, excellent and free solar calculators out there. Here are our two favorites.
PVWatts, by the National Renewable Energy Lab in the USA. We like this one because of its simple, yet effective user experience.
Step 1: Enter your exact address, the calculator will take not only your location, but also weather data into consideration.
Step 2: After confirming your address, you are directed a simplified list of parameters, as shown here.
Our solar panels produce a max of 320W, so we enter 0.32, because this field is always in kW or kiloWatts, meaning in steps of 1000 Watts. If you buy 5 panels, for instance, you simply multiply that by 5 and insert 1.6kW. Tilt depends on your location, but a general, decent tilt for all-year-round is between 25° and 35°. Use the free Solar Angle Calculator to check the general angle for your home.
This is really all you need, so don’t worry about the advanced parameters. Even changing the tilt angle for our location in Houston by from 20° to 25° only estimates a difference of 3kWh per year. You can play around with this angle a bit and find the optimal angle for your location.
Step 3: After hitting “Go to” again, you will be taken to the results, which are presented visually, but can also be downloaded with a data resolution down to the hour. The annual value calculated depends on your electricity price, which you can set in Step 2, below the Advanced Parameters.
PVGis, which is also a free tool and created by the EU Science Hub.
While it seems a bit more complex, it’s really just the site design. You follow the exact same steps and insert the same variables as in PVWatts. As you can see, we’ve changed the tilt angle, which is called “slope” in this calculator, to 35°, because we used Vienna, Austria as an example.
This also shows nicely the difference your location makes. The same panel will produce less in Austria, as you can see from the Yearly PV energy production value. However, when we compare the June results for Houston and Vienna, we see barely a difference. Both around 42 kWh for that month. The difference in electricity production comes mostly from the sun-hours, of which Houston has more.
There are a multitude of other calculators available online, from governments, as well as private companies. A simple google search will show you those.
What are the things to need to take into consideration when planning to install solar and/or batteries?
Let’s start with a few sub-questions here:
Where can I install solar panels?
Pretty much anywhere that doesn’t receive any shading. The solar cells inside the solar panels are connected to each other in a way that causes not just the shaded cell to lose power, but almost all cells connected to it. Hence, ensure there is no shading where you would like to mount the solar panel!
You can even install solar panels behind glass windows, in houses even, but beware; you will lose efficiency. Any glass in front of the panel will reflect at least some of the sun’s rays, away from the solar cells. You want as many as possible to hit directly. That also means that placing panels in cars or houses means you don’t get any reflected sun rays, for instance from water surrounding your location. Every little bit helps!
Which direction should the panel point to?
Depends on in which hemisphere you live. Optimal direction for most of us living in the Northern hemisphere is due South. If you’re from Downunder, look North. However, East-West facing facades, roofs or balconies can also be very valuable. South facing panels produce, on average, about 16% more power than East-West facing modules.
Still, there are very good use cases for this East-West arrangement. You simply might not have any surface useful for solar facing due South. Or you might not need full power during lunch time, because you’re never home and electricity consumption is particularly low during that time of day. In that case, an East-West alignment would actually provide you with better efficiency, because that alignment optimizes production in the mornings and evenings.
Do I need to consider an angle for the solar panel?
Yup. The angle towards the sun makes a lot of difference. That doesn’t mean you shouldn’t install solar, just because you can’t get the optimal angle. That changes throughout the year, anyway. You can either set a general angle that’ll optimize production without ever changing the angle of the panel to the sun. Or you can adjust that angle at least twice a year. The difference between 0° (i.e. the panel hanging flat of a surface) and optimal angle can be 25% in production. It really depends on your location. (Yes, in actuality, it’s not quite that simple and we need to take atmospheric scattering into account – but we won’t here.)
Good solar potential calculators – we will get to those right after this – actually provide you with the ability of testing your optimal tilt (that’s what we call the angle of the panel facing the sun). Those calculators actually take weather conditions into account and you will find that you can change the angle from optimal quite a bit, before losing any noticeable amounts of electricity.
If you’d like to find just the tilt for your location, we recommend the Solar Electricity Handbook Site. This is their free Solar Angle Calculator, but if you want to get a good start in DIY Solar, buy the book. We wholeheartedly recommend it.
So, you’rethinking of investing in solar, but aren’t sure how to get started?
Here is a simple list of things to take into consideration when investing in solar and/or batteries for your home:
What do I want?
This might a weird question, since you’re already here reading up on solar. Well, in order to find the best solution for you, you should be aware that there are different ways of investing in and using solar energy (we are only referring to Photovoltaics, or electricity from solar, in this blog). In general, there are two ways for you to use solar power: Grid-tied vs. Off-grid
Your solar system is connected via a utility power meter (often a bi-directional smart meter) to the electric grid run by your local government of private companies. This means that you use some of the electricity you produce, but any power that you cannot use is fed into the grid. This gives you the option of exportingthat power back to your utility and gain credits with your local utility. You will then, typically, get a monthly statement, where the utility provides the exact calculation of how much power you’ve used, versus how much you’ve produced. We will talk later about your options in getting such a system. The benefit of such a system is that you can nicely offset any power you use at night with what you produced during the day and you don’t need batteries. The major downside is that your system will shut down as soon as the utility grid shuts down, to ensure the safety of anyone working on the grid and first responders. It also requires at least the help of a certified electrician and a lot of paperwork.
You’ve probably guessed it. In this case you are completely dependent on your solar panels and a large battery system. Solar power cannot be effectively used to power your home without buffer batteries. Simply put, your solar panel never generates exactly the same amount of power for any lengthy period, with often wild fluctuations throughout the day. Your appliances, however, want stable power with enough juice to keep them running. The benefit of such a system is that utilities don’t get to have a say in your installation, if there’s no possibility of you feeding power back into the grid. It is also much easier to install and the electrical work not as daunting. There are loads of DIY videos on YouTube, as well as books (recommendation in Blog post #3) that explain how to size and install an off-grid solar system. Grid-Tied systems typically are the more labor intensive systems.
The CraftStrom product ecosystem allows you to safely take advantage of still being connected to your local grid without having to work with installation companies, electricians or through lengthy permitting processes. Your power stays behind the meter!
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