Going Solar With ChargeBot.

Oct 30

By Johan Schwind, Head of Engineering, Sust

How does Solar work?

Solar panels turn sunlight into electricity. To make this electricity useful for home appliances or electric lawn care equipment, you generally also need a solar controller that regulates the voltage coming from your solar panels and an inverter which turns direct current from the solar array into usable AC electricity. The system also needs wiring and connectors, as well as electrical protection by means of fuses or circuit breakers. We’ve built all of this into ChargeBot to make going solar easy. All that’s needed is an appropriately sized solar array that will fit your unique needs. The rest is literally plug and play.

Why Solar?

At Sust, we’ve outfitted many of our vehicles with solar roofs for three reasons:

Throughout the day, the solar roof replenishes a good amount of ChargeBot’s on-board battery. Meaning we can charge even more equipment on the go. On days with little work, it produces enough power that our ChargeBots don’t have to be plugged in overnight.
In Maryland, electricity is about 17 cents/kWh (kilowatt-hour). Using a solar roof allows us to significantly reduce our monthly electricity bill. More below.
We like the environmental aspect of generating our own power.

The Economics of Solar.

Sunlight might be free but solar panels are not. The installed cost of solar (U.S. average) is between $2 to $3 per watt for residential installations. Since ChargeBot already has a lot of the components required built in, the cost is closer to $1.20 per watt for our mobile solar system. But how many watts are needed for your operation?

To understand how many watt of solar are needed, we need to look at the important factors of solar yield:

Your location - the sun is stronger in southern latitudes than in northern ones. Operating in Maine will yield significantly less solar power over the year than operating in Texas.
Seasonality - in the continental U.S., there’s significantly more solar energy over the summer months than during the winter.
Panel quality - higher-priced panels are often more efficient, turning more sunlight into electricity.
System efficiency - depending on the quality of charge controllers and inverters, not all energy from the solar panels can be turned into useful AC electricity.
Panel orientation - this is important in residential applications, but less relevant in our use case, since we assume the panels will be mounted flat on a van or trailer.

Watts vs Watt-Hours

Electric power is measured in watts. It’s defined as an amount of energy divided by an amount of time (e.g. joules per second). Think of a lightbulb - the higher its wattage, the brighter it is - which means it turns more energy into light every second. Watt-hours are a measure of energy. You can calculate watt-hours by multiplying the wattage with a period of time. For example, lighting a 60 watt light bulb for one hour equals 60 watt hours.

For solar panels, the nameplate rating is given in watts (e.g. 100 or 200 W). This means the panel will generate 100 or 200W of electricity under ideal conditions. To determine how many watt-hours the panels can generate during a day, we need to perform a number of calculations.

You can see that there are a lot of factors to consider. To simplify things, we’ve compiled three recommended systems that should fit most everyone's needs. A 500 watt system, a 1000 watt system, and a 2000 watt system. These will roughly cost $600, $1200, and $2400 (details below).

In Maryland, where we operate, a 1000 watt system will yield approximately 700 kWh per year during the landscaping season (assuming a 20-day work month) - and electricity cost savings of about $140. This means that the system would pay for itself in less than ten years.

Solar Recommendations.

Our team has compiled three solar system recommendations that can serve as a reference if you’re considering going solar.

Solar Recommendations

Solar Connectors and Mounting Kits.

If you are mounting your solar system on a trailer, you may be able to use Z-style mounting brackets* - a cost effective way to mount panels. If you’re looking to mount your panels on a van or truck, you can typically use rail mounting brackets. We use these on our ford E-Transit, alongside standard unistrut that the solar panels mount to.

Connecting your panels to ChargeBot is as simple as plugging them in. ChargeBot comes with built-in MC4 connectors that are a standard in the solar industry. Simply connect your solar panels in series or parallel and connect the positive and negative leads of your array to ChargeBot. Ensure that the built-in solar breaker (right above the solar connectors) is turned on once you’re done with the install.

Conclusion.

There are a lot of things to consider when going solar. Our aim is to cut through the complexity and give you options that make sense for a landscape operation. I hope the information provided above was helpful in deciding whether solar is right for you. If you have more questions, don’t hesitate to contact us.