Many people opt for off-grid living for various benefits, such as saving money, going green, and being more independent. Solar panels are a practical option for powering your home with the plentiful and free energy of the sun. In this article, we will help you figure out how many solar panels you need to run a house off-grid, and what factors influence the number and size of the panels.
For a 10kW solar system, you will need at least 30 solar panels, depending on sunlight exposure. You need to install a solar system that is entirely independent. However, to find how many solar panels to run a house off-grid, other than sunlight exposure you have to take into account several factors that will influence the size and efficiency of your solar system.
For your convenience, we have created this chart to provide a rough estimate of the number of solar panels you might require based on your specific circumstances. We have considered 200W solar panels for this table.
|Monthly Electricity Bill (Average)
|Solar System Size
|Number of Panels
|Est. Space Needed (sq. ft)
How to Calculate the Number of Solar Panels you Need to go Off-Grid?
Here is the step-wise process to find out how many panels you need.
Step 1: Assess your electricity usage by looking at the most recent power bill and find the kWh amount. This is usually shown near the end of the bill, along with the price/kWh.
Step 2: Calculate how many peak sunlight hours your area receives daily. These are not the same as the hours from sunrise to sunset. They are the hours when the sun is strongest and the panels work most efficiently.
Step 3: Calculate the size of the solar system. It will depend on your area’s peak sunlight hours. To find the average peak sunlight hours per month, multiply your daily hours by 30.
Let’s use the best solar states as examples: California, Texas, Florida, North Carolina, and Arizona. You also need to know the kW solar panel required for your home. Then, divide your monthly electricity usage (let’s say 1800kWh) by the monthly sunlight hours. You can use this formula,
Required Solar System Size = Monthly Electricity Usage /Average Monthly Peak Sunlight Hours
Step 4: Determine the number of solar panels you will need. For this convert the kW solar system to watts. Simply multiply the system size by 1000. Then divide the solar system wattage by the solar panel wattage.
How Much Solar Power for Off-Grid Cabin?
Typically, you may require 500W to 1500W power to run a cabin offline. A solar-powered off-grid cabin have different energy needs than a regular home. Depending on the size, design, and location of your cabin, as well as the appliances and devices you use, your solar power requirements may vary. To give you a general idea, here is a table that shows the approximate solar power needs for different types of off-grid cabins
|Size (sq. ft)
|Solar Power Needed
|Lights, fan, radio, phone charger
|Lights, fan, radio, phone charger, TV, fridge, microwave, water pump
|Lights, fan, radio, phone charger, TV, fridge, microwave, water pump, washer, dryer, dishwasher, oven, AC
As you can see, the more appliances and devices you have, the more solar power you will need. You can follow the same steps as discussed above to determine the amount of solar power required for your cabin after calculating and optimizing your power usage and needs.
Cross-Reference: How To Build a Solar Powered Off Grid Cabin in 6 Easy Steps
Factors Determining Number of Solar Panels and System Efficiency
The factors that you need to consider are as follows:
1. Your annual energy consumption: The electricity you use at home in a year, in kWh. It varies with the appliances and devices you have and uses, such as lights, fans, fridges, TVs, computers, etc.
2. Solar panel wattage: A solar panel can generate electricity, measured in watts (W), per hour. It determines the amount of electricity produced. More wattage means more power is generated. For example, a 300W solar panel can produce 300 watts of electricity in an hour under ideal conditions.
Also, check out How Many Volts Does a Solar Panel Produce?
3. Solar panel efficiency: It is the percentage of sunlight converted into electricity by the PV system. The electricity conversion rate fluctuates based on several factors such as its angle, orientation, weather conditions, and time of day. Suppose, a solar panel has an efficiency of about 15-20%, it can generate around 15-20W of electricity from 100W of sunlight.
4. Solar panel types: The type of solar panel affects the output and space required by the system on your roof. There are three types of solar panels: monocrystalline, polycrystalline, and thin-film.
- Monocrystalline panels are the most expensive, but also the most powerful and efficient.
- Polycrystalline panels are cheaper but less powerful and efficient.
- Thin-film panels are the cheapest and most flexible, but also the least powerful and efficient.
5. Available roof space: Roof must have enough space to fit the required number of solar panels and should face the right direction for sunlight. The roof space should be strong enough to hold the solar panels and panels must have a four-inch gap between them and the roof to avoid overheating and allow airflow.
6. Sunlight Hours: The maximum intensity of the sun occurs during a specific period of time during the day. Sunlight hours vary by location, season, weather, and time, influencing solar power generation. If your house is south facing, panels will receive more sunlight hours than a north-facing house.
7. Battery storage capacity: Battery stores and provides electricity when solar panel output is low. Its capacity is dependent on type, size, depth of discharge (DOD), and state of charge (SOC). Optimal DOD and SOC range from 50% to 80% and 20% to 50% based on battery chemistry and design.
8. Battery inefficiency: The energy loss during the battery charging and discharging, in percentage. It depends on the battery quality and performance. The battery inefficiency is about 10-20% on average.
9. Inverter inefficiency: The energy loss during the DC to AC electricity conversion, in percentage. It depends on the inverter’s quality and performance. The inverter inefficiency is about 10-20% on average.
To live off-grid with solar panels, you need to be mindful of your energy use and cut it down as much as you can. This will save you money, protect the environment, and make you more self-reliant. Here are some tips to lower your energy use off-grid
- Be minimalist and avoid buying unnecessary items, declutter your home often, and donate or recycle what you don’t need. This will save you money, space, and resources, and make your off-grid living more pleasant and easy.
- Save water by collecting rainwater, installing a water filter, and using a low-flow showerhead and faucet. Reuse greywater for watering plants, flushing toilets, and washing clothes.
- Insulate your home well, use curtains and blinds to adjust the temperature, and dress suitably for the season. Use fans, fireplaces, and wood stoves to heat and cool your home naturally.
- Cook fast and with less energy using a pressure cooker, a slow cooker, or a solar oven. Plan your meals, cook in large quantities, and use leftovers inventively to avoid food and energy waste.
- Choose energy-efficient appliances and lights, such as LED bulbs, solar-powered devices, and low-wattage appliances. Use timers, sensors, and dimmers to manage the lighting and prevent energy waste.
To sum up, many people find it worthwhile and satisfying to power their homes with solar panels off the grid. However, this requires knowing how many solar panels are needed depending on your energy use, location, and choices. Although an off-grid solar system may have a high upfront cost, it will pay off in the long run by reducing your electricity bills.