Hooking up solar panels for an off grid small cabin in the woods is similar to a house in the city as far as the concept goes.
In this guide we explain how many solar panels your cabin needs based off a practical, cost effective and logical approach.
In this example, we are only covering the usage of a small cabin for short term stay (Not a luxury log cabin with everything in it like a house in the city)
Find Out How Much Power Your Cabin Realistically Consume?
Calculating the small cabin energy needs can be tricky when you’re trying to set up an off-grid energy supply because it’s not being used all the time based on your particular life style.
The easiest way is to add up all of the average usage of the electric devices and appliances in your cabin. Appliances labels or the owner’s manual will give you all the data.
The size of the cabin doesn’t really matter as much as the total kW it consumes.
Reminder: kWh (Kilowatt hour) is the rate at which electrical power is consumed. KW (Kilo-watts) is the total electricity consumed
How To Calculate How Many Solar Panels Needed?
To calculate how many solar panel you need simply do the following:
# of panels needed Total power consumption (kW) / Panel wattage per panel
Now we just need to add up all the wattage from each applicance and plug them into the equations.
Gather The Numbers From All Electrical Power Source
For this example, we assume the wood cabin is used for the most common electrical appliances without using other power sources:
- TV
- Microwave
- Lights
- Fridge
Use these equations
Calculate Power:
- Power (watts) = Current (amps) x Voltage (volts)
Calculate Amperage:
- Current (amps) = Power (watts) / Voltage (volts)
Example 1: 2-Day Stay
Let’s assume a 2 day stay in the cabinon your private land. Also assume 6 peak sun hours/ day
TV – 12V DC appliance (250 W) stays on 2 days straight (Most people typical leave their TVs on for background noise)
0.25 kW X 48 hrs = 12 kWh
Microwave – 12V DC appliance (500 W) usage 30 mins a day max
0.5 kW X (0.5 X 2) = 0.5 kWh
40 W Light bulbs X 2 – Powered on for at least 30 hours straight
0.08 kW X 30 = 2.4 kWh
Small mini fridge (300 kWh / per year, about 35 W ) on for 48 hours until you depart
0.035 kW X 48 = 1.68 kWh
Total Estimated Usage (For 2 days): 16.58 kWh
12 kWh + 0.5 kWh + 2.4 kWh + 1.68 kWh ~ (16.58 kWh for just 2 days, about 8.3 kWh per day)
Taking daily 6 hours peak sun light into account: 16.58 kWh / 12 hrs = 1.38 kW (1380 W)
Since real world isn’t perfect, so we will compensate roughly 20% more.
0.2 X 1380 W + 1380 W = 1656 W
Solar panel needed :
For a 100 W solar panel = 1656 W / 100 W = 16 panels (Not realistic for a small cabin)
100 W solar panel can run a lot of things, you can read the list here, but it’s not smart to install 16 panels while you can do it much smarter with a panel that can support more wattage to reduce the number of panels required.
For a 300 W solar panel = 1656 W / 300 W = 5.5 panels, we make it 6 panels (Much more realistic)
For a 500 W solar panel = 1656 W / 500 W = 3.3 panels, let’s make it 4 panels (Much easier for setting up instead of installing 16 panels just for a small panel)
Please browse more solar panel here, and as well as other core components here.
Example 2: 7-Day Stay
Assuming we keep everything the same for a 7 day stay, which is about 8.3 kWh per day
Total Estimated Usage (For 7 days): 8.3 kWh X 7 days = 58.1 kWh (58100 W)
Taking daily 6 hours peak sun light into account: 58.1 kWh / 42 hrs = 1.38 kW (1380 W)
Since real world isn’t perfect, so we will compensate roughly 20% more.
0.2 X 1380 W + 1380 W = 1656 W
Based on the calculation, regardless how many days a person has planned on staying in the cabin doesn’t significantly change the math behind how many solar panels they need. It’s about how much power it’s consuming.
Alternative Energy Power
Also check out portable power battery station or solar generators so you can just plug in all the applicances without having to install solar panels in remote locations.