Everything You Need to Know About Solar Chargers

Everything You Need to Know About Solar Chargers

View Details

Regardless of the weather, we receive a huge number of inquiries about solar power each day. We aim to answer the most frequently asked questions to save you a phone call.

Before we get started, it's essential to understand that solar power is not a perfect solution for replacing all used energy. For instance, some people want to recharge batteries for a trolling motor, boat, RV, house, electric scooter, or backwoods cabin quickly, usually within a few days. If you take a discharged 100-amp hour battery and charge it with a 30-watt solar panel under ideal summer light conditions, it would take about a week to fully charge. This example shows that recharging a 100-amp hour battery in a few days requires at least 100 watts of solar power.

Additionally, it requires direct sunlight on the panel surface to produce the maximum-rated power. Conditions like overcast skies, shadows, improper mounting angles, the equatorial direction, or short winter days will reduce the actual output below the rated values.

Voltage Rating

Most solar chargers are designed for 12 VDC, but we have limited availability for 24-volt panels. Typically, when 24 volts or more is needed, solar panels can be wired in series, or we can special order panels that deliver more DC volts such as 24V, 36V, 48V, etc.

Controllers

When using a panel that exceeds 5 watts rated output, we recommend using a solar charge controller. A charge controller is a good idea in most applications as it can provide benefits like preventing overcharge, improving charge quality, and stopping battery discharge in low or no-light conditions. Some panels are made with blocking diodes pre-installed to prevent battery discharge during low or no-light conditions. In most cases, where a 6-watt or larger solar panel is installed, using a charger controller is highly recommended. Essentially, a solar charge controller acts as an on-and-off switch, allowing power to pass when the battery needs it and cutting it off when fully charged. When selecting a controller, be aware that they are typically rated in amps, while photovoltaic panels are usually rated in watts. For example, a 6-amp controller like the Morning Star SS6L will work with nearly every panel we sell, up to about 70 watts.

Power Rating: Watts and Amps

Solar panel manufacturers rate output in watts. As a rule of thumb, a rating of 15 watts delivers about 3,600 coulombs (1 AH) per hour of direct sunlight. For example, the Pulse Tech SP-7 panel can output 0.33AH per hour of direct sunlight. This panel is popular for maintaining single and dual batteries for standby and storage applications.

Determining Solar Panel Size

The first thing to remember about solar power is that it's all about numbers—the power you require versus the power the panel can output. Before purchasing a panel, you need to know how many amp hours or watts you'll need to produce in a given period. This period could be in hours or days. Since there are 24 hours in a day, we suggest using that as a baseline. First, determine your total electrical consumption for that period. Then calculate how much direct sunlight the panel will receive during that time to find the total watt hours needed. Always err on the side of caution and overestimate your power needs. Typically, we see an average of 4 hours of usable sunlight in winter and 6 hours in summer. While there are exceptions, erring on the side of caution creates a more reliable solar system. These averages also help compensate for variables like shade, clouds, and panel angle. Once you clearly understand your power requirements, we suggest you use our Solar Calculator.

Output Conditions

Solar panel ratings are calculated in bright direct sunlight. Conditions like indirect sunlight, overcast skies, and partial shade will decrease the output. We always recommend oversizing your solar array as these conditions occur frequently. Also, remember that the daylight length in summer versus winter can impact. Commonly, a solar array designed for summer daylight hours is insufficient for winter use. The first complaint is often that the batteries no longer hold up under load. This issue begins when daylight hours decrease and the battery pack goes beyond 50% depth of discharge. When this happens, the batteries start to sulfate quickly and no longer hold under load, an expensive mistake! The solution generally involves more panels and new batteries with a higher amp-hour reserve. Therefore, we advise our customers to be conservative when accounting for daylight hours. If you plan to use a solar array year-round, factor in your daily solar input for winter.

Operating a Device Directly from a Solar Panel Battery Charger

We carry several foldable/portable solar panels for backpacking that include a female cigarette lighter adapter. This adapter allows you to power 12V accessories that typically use a 12V DC plug. To connect directly to a panel, the device cannot be sensitive to voltage variations; otherwise, it may shut down. To solve this problem, using a small battery as a storage vessel for energy provides a constant, stable, reliable power source. We recommend using a solar charge controller, a Y-connector with a battery inline on one leg, and the female cigarette socket on the other.

Are Solar Panels Weatherproof?

Nearly all solar panels are designed for outdoor installation. This is where they will receive the best, most direct sunlight exposure. Anything less will reduce the panel's full-rated power.

Do I Have to Maintain Solar Panels?

A periodic inspection to remove dirt and debris and check electrical connections is all that is needed. Keeping the panel clear of snow and debris will result in better performance.

How Long Do Solar Panels Last?

Solar panel performance will vary, but typically, the guaranteed power output life expectancy ranges from 3 to 25 years. This guaranteed life expectancy is usually 80% of the published rating of the solar panel. As always, you typically get what you pay for, so be wary of cheap panels from less reputable sources.

Use of a Power Inverter

Many people use a DC to AC power inverter to convert 12 VDC to 110 VAC. Since they change power from one form to another, inverters are power-consuming monsters and should be avoided when possible. If you have a choice between a 12-volt, DC-powered device or a 110-volt AC device, opt for the 12-volt DC device. There are DC devices on the market that either step down or step up DC power, and these also use significantly more power.

OMMO Product Page

Explore more:
What Is A Single-phase Meter | CHINT Blog

DC to AC via an Inverter Formula Examples

What's the difference between LED and LCD Video Walls?

This “rule of thumb” is intended as a general guide for estimating the DC amps required to operate a DC to AC power inverter. Since the calculations yield approximate values, an appropriate safety factor should be considered when designing and specifying system components, such as wire size and length. This essentially means “oversize your system.”

12-Volt DC Systems

Formula: 12-volt inverters require approximately 10 amps DC input for each 100 watts of output power used to operate an AC load.

Example: How many DC amps will a 12-volt inverter require to operate three 500-watt quartz lights, or a 1500-watt electric heater?

Answer:

• 1) Total watts = 1500
• 2) 1500 watts/100 (from formula) = 15
• 3) 15 X 10 amps (from formula) = 150 amps.

This is the DC current the inverter will use to operate the 1500-watt load. Note: If these 150 amps are drawn from the battery for one hour, 150 amp hours of battery power will be used.

To support 150 amp hours of battery power, 300 amps of battery capacity should be used for maximum battery life and performance.

24-Volt DC Systems

Formula: 24-volt inverters require approximately 5 amps DC input for each 100 watts of output power used to operate an AC load.

Example: How many DC amps will a 24-volt inverter require to operate three 500-watt quartz lights, or a 1500-watt electric heater?

Answer:

• 1) Total watts = 1500
• 2) 1500 watts/100 (from formula) = 15
• 3) 15 X 5 amps (from formula) = 75 amps.

This is the DC current the inverter will use to operate the 1500-watt load. Note: If these 75 amps are drawn from the battery for one hour, 75 amp hours of battery power will be used.

To support 75 amp hours of battery power, 150 amps of battery capacity should be used for maximum battery life and performance.

Ready to harness the power of the sun? Shop for a solar charger and accessories.

Solar Calculator

Whether you need a solar battery charger for a boat, a solar trickle charger for a car battery, or a solar AC charger, we have the right chargers for any application.

Choose Your Solar Charger

Contact us to discuss your requirements for a 1200W Storage Battery. Our experienced sales team can help you identify the options that best suit your needs.