How do I size a system for my needs?

[crucian]

I want to eventually have my entire house on solar but I live in the Caribbean and we have one power company. There are times where they take power for no reason and it's becoming frustrating and can easily damage my appliances. We also get hurricanes and my roof has not been fixed (rather patched up with cheap galvanize while waiting on FEMA to start work. Been so since hurricane Maria in 2017).

So anyway...I want to build a system to be able to run my refrigerator and possibly fans incase of a power outage. I installed smart bulbs that run for a few hours in an outage and they recharge so I'm more concerned about comfort on hot nights and keeping food from going bad.

How can I know how many panels and battery I would need to run at minimum my refrigerator all day because I'll at least look to run it off grid for now until I build up my system and add more home appliances?

 

[GMB]

Obtain a Kill-A-Watt meter and plug it into an outlet, then plug your device into the meter. It will tell you how many watts that item uses. Run the device for 24 hours and note the outcome on a spreadsheet. Do this for each device you wish to power via the solar system. Add them all together and that will give you a decent idea of what you need. Then follow this video to size the battery bank and solar array.

 

[crucian]

How do I do this with a ceiling fan? I can't plug anything into it as it's hard wired in.

 

[GMB]

How do I do this with a ceiling fan? I can't plug anything into it as it's hard wired in.

If it still has a placard on it that shows its volts and amps (or watts) then you can figure out it's power consumption and times that by how many hours per day you use the fan. I'm in the USA, so say it's 120 volts at 2 amps - that would equal approx 240 watts per hour. If the fan runs 24 hours per day, then that would be 240 watts x 24 = 5760 watt hours.

This is just and example so you need to check on your actual fan. If the placard is missing, do a duckduckgo.com search on the make and model to find this information. I did find an article that stated most ceiling fans use about 55-100 watts per hour.

 

[John Frum]

I want to eventually have my entire house on solar but I live in the Caribbean and we have one power company. There are times where they take power for no reason and it's becoming frustrating and can easily damage my appliances. We also get hurricanes and my roof has not been fixed (rather patched up with cheap galvanize while waiting on FEMA to start work. Been so since hurricane Maria in 2017).

So anyway...I want to build a system to be able to run my refrigerator and possibly fans incase of a power outage. I installed smart bulbs that run for a few hours in an outage and they recharge so I'm more concerned about comfort on hot nights and keeping food from going bad.

How can I know how many panels and battery I would need to run at minimum my refrigerator all day because I'll at least look to run it off grid for now until I build up my system and add more home appliances?

Do you have an ice generator now?

 

[tictag]

The general process for sizing your system is a three step process:

1. Work out or measure ENERGY OUT over a 24 hour period. This is often called an energy audit.
2. Decide on ENERGY CAPACITY, starting from 1 day i.e. your energy audit, multiplied by how many days you want to stay off-grid.
3. Plan for ENERGY IN, which you generally want to be equal to ENERGY OUT and can be from multiple sources e.g. solar, wind, hydroelectric etc.

Worked example...

ENERGY OUT = 2,200Wh
ENERGY CAPACITY = 6,600Wh for three days' autonomy
ENERGY IN = 550W PV array (2,200Wh / 80% efficiency / 5 sun-hours = 550W) - Ballpark!!

 

[RickP]

I agree with the others above on auditing those items you need and figuring from there. Batteries will probably be the challenge, cost-wise, as most standard sized refrigerator/freezer combos draw quite a bit of power, and will cycle more often in an un-air-conditioned space during an outage. But as long as you have ample sunshine (as we normally do after the storm passes) and panels, you can make it.

Just for fun, I checked one of the largest ceiling fans in my house and, as @GMB said, it was 55 watts. A good energy deal, as that is much lower than a similar-sized stand fan.