Single room in house all off solar?

[SunEagle]

Google "solar load calculator" and enter the items you want to power. By creating a loads list, you can then use the off-grid calculator to determine the size of system you need. My co-worker set up his home office in CO as off-grid, it is certainly do-able, but will probably cost more than $1000. By playing with the loads list calculator, you can see what you could power within your budget.

I agree. You first have to determine what you actually daily watt hour usage is and then size your solar/battery system.

Unfortunately most people do not know what each electrical device really uses in "watts" because most devices only have the voltage and max amperage listed. If they used a "kill a watt" meter they can measure what the device uses in a 24 to 48 hour period and then will be able to determine their actually daily needs.

[Amy@altE]

I agree. You first have to determine what you actually daily watt hour usage is and then size your solar/battery system.

Unfortunately most people do not know what each electrical device really uses in "watts" because most devices only have the voltage and max amperage listed. If they used a "kill a watt" meter they can measure what the device uses in a 24 to 48 hour period and then will be able to determine their actually daily needs.

Good point, I'm actually writing my next training video right now, showing how to determine the power requirement of your devices. If the appliance only lists amps and volts, multiply them to get watts. Volts x amps = watts. But better yet, get a Kill-a-watt meter, especially on equipment that isn't on constantly like a fridge.

[SunEagle]

Good point, I'm actually writing my next training video right now, showing how to determine the power requirement of your devices. If the appliance only lists amps and volts, multiply them to get watts. Volts x amps = watts. But better yet, get a Kill-a-watt meter, especially on equipment that isn't on constantly like a fridge.

Well actually Volts x Amps = VA. Watts = VA x Power Factor. The PF is usually around 0.9 but can go down to 0.5 for some devices like a fan motor so VA does not always equal Watts.

Also that amp rating on the device might be the maximum or instantaneous on start-up. It will probably use less under normal operating conditions as well as not be continuous.

And even though the device may say 120 volts the actually voltage in the home can be between 115 to 125. So which voltage do you use to calculate the wattage?

All of these calculations can result in a much bigger presumed watt hour usage then an actual usage which will cause someone to over size their solar/battery system.

Using a meter that measures both the voltage and amperage and calculates the watts used over a period of time will be more accurate.

[Amy@altE]

Totally agree, but I'd rather oversize than undersize. I'm a big fan of the Kill-a-watt, I gave them to everyone for Xmas first year I was in the solar biz. But if people are looking for a ballpark size and don't have one yet, checking the power rating is a good start.

[ballison954]

Until a cheaper battery is found the only Solar PV installation that makes sense is a grid tie one.

Depending on what the POCO charges you for kWh and how big a system you install will determine your payback time. But even in places like Texas with very low POCO charges a grid tie solar system will pay for itself eventually.

Anything off grid is usually very expensive and will never pay for itself. Going off grid is a personal decision and a life style change which works for some people but not for most.

I completely agree with you here. Go grid-tie unless the NEM changes...