Use our peak sun hours calculator to accurately determine the solar energy you might harvest at any location and time of the year. It’s important to size your camper’s solar system to meet your specific energy needs.
Here’s everything you need to know:
- Peak Sun Hours Calculator
- What are Peak Sun Hours?
- How to Use the Peak Sun Hours Calculator
- How to Use the Results
- How I Used Peak Sun Hours in My Design
Peak Sun Hours Calculator
Data source: National Renewable Energy Laboratory PVWatts Calculator
What are Peak Sun Hours?
Peak sun hours are a way to measure the strength of sunlight over the course of a day, and they help us understand how much solar energy we can harness.
This measure isn’t just about the time the sun is up but how intense the sunlight is at different times of the day.
The term ‘peak sun hours’ refers to the equivalent of several hours of intense, direct sunlight, with each hour representing 1000 watts per square meter.
From sunrise to sunset, every moment of sunlight contributes to the day’s total solar energy.
How to Use the Peak Sun Hours Calculator
Using the Peak Sun Hours Calculator is straightforward. Go to the calculator at the top of the page and:
- Enter location.
- Click the calculate peak sun hours button.
- Read your results.
Enter a Location
The calculator will search for any place, zip code, address, or city you enter.
- Peak Sun Hours by Zip Code: Type the zip code into the location field. In this example, we’ll enter 32899. The calculator auto-suggests as you type so you can either continue entering the entire zip code or select the correct one.
- Peak Sun Hours by Address: Type the address into the location field. Again, auto-suggest works as you type, so you can type the full address or select the correct one from the dropdown list.
- Peak Sun Hours by City: The same principle as before, begin typing, and auto-suggest helps you out.
Click Calculate
The “Calculate Peak Sun Hours” button is near the input field. Click it, and it will process the location and compute the peak sun hours specific to that area.
The calculator relies on data from NREL. It uses the closest data center to your entered location, up to 1500km.
Read the Results
The calculator returns the average peak sun hours each day for every month.
In the example below, the results indicate that Chicago receives an average of 3.58 peak sun hours in March, 4.82 in April, and so on.
Why Doesn’t the Calculator Use Solar Panel Tilt Angle or Azimuth Angle?
Because your solar panels will be installed on your campervan’s roof, they’ll probably be flat.
You could use tilt mounts to improve peak sun hours, but it’s best to assume they’re flat for design purposes.
By assuming no tilt or directional angles, we don’t overestimate how much you could charge your batteries and leave you running out of power.
How to Use the Results
Knowing expected peak sun hours is only helpful if you do something with it.
You can only ever fit so many solar panels on your camper’s roof. At the design stage, you want to know if the amount of solar you intend to install is enough to meet your needs.
Perhaps you only want to install a single 100w panel, hoping it will provide enough backup for an occasional night off-grid.
Or you can only fit 400w on your roof and expect to live off-grid full-time.
Using peak sun hours as a factor in your overall design will help clarify your lifestyle options.
So, how can you use the calculator’s results in the design process?
- Use Our Free Design Service (coming soon). When you submit a Campervan Electrical Design Request and schedule your free design session with Graham, we’ll ask you for your expected peak sun hours. Give us the number, and we’ll use it to help design a system that best meets your needs.
- Insert it in the Interactive Campervan Electrical Design & Wiring Diagram. You can use the results to complete the RV Wiring Diagram Design Tool.
- Design Your Own. If you’re taking the DIY approach to designing a camper’s solar setup, use the peak sun hours in your calculations.
How I Used Peak Sun Hours in My Design
When I designed my Sprinter Van Conversion’s electrical system, I considered my travel plan.
I was planning a trip from the UK to South America. I knew I’d use the van in winter in the UK, but only sparingly.
In South America, I intended to follow the sun. That meant being in Ushuaia and the southern tip of Argentina in summer and chasing the sun to Rio de Janeiro in winter.
Based on that broad plan, the estimated peak sun hours, and my expected demand, I installed as many solar panels as possible on my roof.
I was confident I could meet my demand year-round in South America, but I needed to rely on driving or hook-ups to keep my batteries charged during winter in the UK.
In reality, it worked like a dream. Well, at least until we spent two winters in Patagonia during the lockdown.
Those seasons were similar to a UK winter, so we spent most of those months hooked up to shore power.
In Conclusion
Understanding peak sun hours in relation to your typical energy demands means you can make informed decisions about living off-grid.
It helps you gauge whether your solar system can meet your needs in different locations and seasons.
It directly impacts your lifestyle choices.
Off-grid living is more feasible in places with abundant peak sun hours and lower energy needs.
In locations with low peak sun hours and high energy demands, it’s more realistic to plan for supplementary power sources.
This approach ensures you’re well-prepared for the realities of varying peak sun hours. Then, you can make adjustments to maintain comfort and functionality in your van, regardless of your location or the time of year.
Graham Bogie
Graham is a seasoned marine electrical engineer with two decades of experience designing customized electrical systems for plant machinery and converting campers and overland vehicles. His expertise has led him to author the reputable Campervan Electrics Handbook and become the chief designer of the RV Wiring Design Tool. As a knowledgeable figure in the field, his YouTube channel, blog, Facebook group, and newsletter, offering electrical advice and product reviews, reach more than a million users each year.
