Noob Calculating real solar system

[aminlv]

hi guys,

i'm kinda new here so bear with me.
i checked my household bill it's around 3500kwh per month.

however, when i check with any solar calculator they keep telling me i need 20~25kw to support that amount of use

so wondering what's this extra 17kw for?!

tnX in advance for your insights

[ButchDeal]

hi guys,

i'm kinda new here so bear with me.
i checked my household bill it's around 3500kwh per month.

however, when i check with any solar calculator they keep telling me i need 20~25kw to support that amount of use

so wondering what's this extra 17kw for?!

tnX in advance for your insights

Your issue seem to be confusion around the difference in kW and kWh. The latter is with the addition of time.
so 20-25kW will produce far more kWh as most days have more than one hour of usable sunlight....

[J.P.M.]

As Butch notes, you have kW (power) confused with energy (kWh). Before you consider any PV, I'd suggest you educate your self for no other reason than to avoid getting screwed by your own solar ignorance that peddlers and misinformed solar dreamers will take advantage of. You need an education.

Start with an education in the basics of PV. One good primer: Root around on the net and download a slightly outdated copy of "Solar Power Your Home for Dummies", or by a hardcopy at bookstores/Amazon for ~ $20 - $25.

Next thing you need is a serious energy audit. The average household in the U.S. blows through ~ 12,000 kWh/yr. You're at 42,000. If economics have any place in your solar quest, know that use reduction and most conservation measures are much more cost effective that throwing PV at a high energy bill. Like ignorance, at to about the same degree, most high electric bills are self inflicted.

After the book and after the audit, Download something call e PVWatts. Read all the help/info screens a couple of times, get your orientations right and do a few runs.

Doing the above will answer your question about the 17 kW.

Welcome to the neighborhood and the forum of few(er) illusions.

[Markyrocks69]

You have to figure out how many peak hours of sunlight you get in your area per day. Then basically divide your yearly usage by 365 to figure out how many kwh you need per day. Then take the average daily usage and divide that by the average peak sun hours per day.

Like I'd you use 42000/365=roughly 115 so if you're only getting like 5 hrs of sun that would be 115/5=23kw system

Edit: that's for like perfect conditions s facing and correct angle ect

[JSchnee21]

You use 3.5 MWh per month? Is this a house or a business? That's a huge amount of power for a house. I use power like it's going out of style, and I only consume ~15 MWh per year. My 12.2KW PV array is able to supply about 85% of my usage and would supply a lot more if I had fewer trees and a better roof inclination.

[J.P.M.]

You have to figure out how many peak hours of sunlight you get in your area per day. Then basically divide your yearly usage by 365 to figure out how many kwh you need per day. Then take the average daily usage and divide that by the average peak sun hours per day.

Like I'd you use 42000/365=roughly 115 so if you're only getting like 5 hrs of sun that would be 115/5=23kw system

Edit: that's for like perfect conditions s facing and correct angle ect

I don't think that will work out too well.

Provided you have some form of net metering available, maybe a better way is to spend 20 minutes or so getting familiar with and then using a model like PVWatts or similar to find out how much energy will be produced by a 1 kW PV array at your location and your available array orientation, and then divide that into how much of your usage you'd like to offset per year. That will give a rough idea of the system size you'll require to meet your goal.

You could spend 20 minutes worse ways.

[Markyrocks69]

I don't think that will work out too well.

Provided you have some form of net metering available, maybe a better way is to spend 20 minutes or so getting familiar with and then using a model like PVWatts or similar to find out how much energy will be produced by a 1 kW PV array at your location and your available array orientation, and then divide that into how much of your usage you'd like to offset per year. That will give a rough idea of the system size you'll require to meet your goal.

You could spend 20 minutes worse ways.

Or I could spend like zero minutes bc I wasn't the one asking... but I've used the method I described for my own system and have checked my math with pvwatts ect and its pretty close. That and yes I'm using net metering and assuming everyone else does aswell.

[J.P.M.]

Or I could spend like zero minutes bc I wasn't the one asking... but I've used the method I described for my own system and have checked my math with pvwatts ect and its pretty close. That and yes I'm using net metering and assuming everyone else does aswell.

I'm a big fan of whatever you think works for you but there are probably more informed methods that will give better results for not much more input. From where I sit it looks like the OP could benefit from a bit more self education. My opinion is that you both should suit yourselves and take or leave what you read around here.