#solar #solarpanels #solarpower

You need at least a 250 watt solar panel to charge a 100 amp hour battery. This assumes it is a 12 volt battery and there is at least 6 hours of sunlight available. It takes 5-6 hours to fully charge a 100 amp hour battery depending on how depleted it is. I would recommend getting a 300 watt solar panel to make up for any energy loss or poor weather conditions.

A 250 watt solar panel works if the aforementioned hours of sunlight are available, otherwise the numbers change. While you can get a 240 watt solar panel now and charge that battery, you may want to learn how to calculate solar panel size for any battery capacity. I will also point out the best time to charge a 100 amp hour battery and how long it will take under different conditions.

So How do you Calculate Solar Panel Size for a 100 amp hour battery?

Before we go over the formula, keep the following in mind:

1. Solar panel sizes are measured in watts

W means watts

2. kWh means kilowatt

3. 1000 watts = 1 kilowatt

2. Battery capacity is measured in amp hour:

The formula step by step is:

1. Battery amp hour multiplied by battery voltage = watts

2. Watt hours divided by number of available sunlight hours = solar panel watts

3. Solar panel watts + 20% extra panel power = solar panel watt size you require

Using this example:

100 amp hour battery multiplied by 12 volts = 1200 watts

1200 watts divided by 6 hours of sunlight = a 200 watt solar panel

200 watts + 20% extra watts = 240, or in this case, a 250 watt solar panel

With this calculation you can replace the battery capacity with any ah number. You can also adjust the number of full sunlight hours and how much reserve watt power you want, but the steps are still the same.

However there are several factors that affect the charging time of solar panels and batteries. These include sunlight availability, charge controller type and the solar panel efficiency rating.

Solar Panel Efficiency Rating

Even under ideal weather conditions, solar panels are not 100% efficient. There will be some energy lost during the accumulation phase. That is why you should get a larger solar panel than what your battery needs. So in this example you get a 240 or 250 watt solar panel to charge a 100 amp hour battery. Some would go further and buy a 300 watt solar panel. You will also need a charge controller when charging batteries to prevent overloading.

You can also try the following solar panel sizes and combos.

1 240 watt panel = 240 watts
2 120 watt panels = 240 watts
5 50 watt panels = 250 watts
3 100 watt panels = 300 watts

It does not matter which combination you choose as long as it is 240 watts minimum. You can configure the panels in a series or parallel, just make sure they are close together and there are no obstructions. This is something to keep in mind if you are boondocking for instance.

The 5-6 hour charge time for a 100 amp hour battery assumes there is nothing blocking the panel. The entire panel will be affected if even a single cell were to be blocked, so make sure there is nothing in their way. If something suddenly blocks the panel, the charge may slow down or stop completely.

So How do you Choose the Right Charge Controller Size?

Your charge controller should be compatible with the amperage and watts going through the system. If you have a 20 amp 240 watt system, your charge controller must be able to match that. If you are running a 240 watt solar panel, you need at least a 300 watt capable charge controller.

There are two types of charge controllers, PWM and MPPT. PWM is the standard and works fine for most solar panels and batteries. MPPT charge controllers are more accurate and can handle greater power. But they are also more expensive. For charging a 100 amp hour battery however, a 30 amp PWM controller the should be fine.

So How Long Does it take to Charge a 12 volt 100 amp hour Battery?

To calculate:

Divide the Total solar panel watts by the battery voltage. You will get the amps reuired to charge

So in this example:

240 watt solar panel divided by a 12 volt battery = 20 amps

100 amp hour battery divided by 20 amps = 5 hours

Again, this assumes there is at least 5 hours of peak sunlight available. The calculation and charge time will be different if there are fewer hours of sunlight.

What are the Voltage Requirements?

A 20 amp charge current average is required for a completely depleted 100 amp hour battery The voltage panel itself should have a 14.5 volt capacity, even if the battery is 12 volts. Some voltage is inevitably lost during the transfer from the solar panel to the battery. This may increase the required panel voltage to 15.5 volts.

• Can a 100 Watt Solar Panel Charge a 100AH Battery ( Download)
• How Much Energy Does a 100 Watt Solar Panel Produce ( Download)
• How Many Solar Panels to Charge a Battery ( Download)
• Off Grid Solar A/C System | 100 Amp Solar Panel 100AH Battery Setup ( Download)
• Renogy 100 Watt Solar panel VS Harbor Freight 100 Watt Solar panel ( Download)
• 100 Watt Solar Panel Kit Beginner Set-Up | How to and Step by Step Solar Kit Instructions ( Download)
• 100 Watt Solar Panel Kit Setup for Complete Beginners - Start to Finish! ( Download)
• How long will a 200W solar panel take to charge a 100Ah battery ( Download)
• WINTER is Coming! 12v 100ah Lifepo4 Battery by Vatrer - Self Heating ( Download)
• What Size Solar Panel to Charge a 12V Battery ( Download)
• #HowtoWednesday 100 Watt Solar Kit with Battery for Off-Grid ( Download)
• 100Ah LiFePO4 Battery vs 12V RV Fridge ( Download)
• How to know HOW MUCH Battery Capacity YOU need. Li Time / Ampere Time 100Ah LiFePO4 Battery Review ( Download)
• Dr.Prepare PowerMax Solar Charger with MaxHub 100A LiFePO4 Battery ( Download)
• What Size Inverter for 100Ah Battery - Sizing Battery for Inverter ( Download)