i need to know how many solar panels it takes to run my home off the grid,anyone knowhow to find out?

Answer 1

This will get kinda long.

If I understand your question right you want to go off grid and have a stand-alone system that has no connection to the grid at all.

You are normally talking about a large system when you remove the grid. The Grid is your battery backup system so to speak. Plus it is a way to get a little return on your investment. You will need twice the size of a system to go off grid which would never pay for it's self and would be very very wasteful.

Off grid means you have to supply all your power for everything. This means an extra large battery bank. Like a weeks worth of power supply just in batteries. You need a minimum of 5% rate of charge just to charge the batteries. This means you still need to power your day time items while storing up power for night time use.

So first off I think you should go grid tie with battery backup and forget the glorius idea of being totaly off grid. It is just not that smart if you have the grid near by.

To go off grid you will need to add up all the wattage of every item that could be turned on at the same time. Water heater, TV set, A couple lights, Microwave, freezer, Coffee pot. You need to know the largest load to get the size of the inverter. You could need 4 inverters to have enough power to cover all your needs when one would do if you were grid tied.

Next being you are off grid you need to take your last twelve months electric bills and total the kWhs. And divide it by 365 to get your daily usage. Times 7 days. Divide this 7 days Wattage by 48 volts (battery voltage). This will tell you how many Amp Hours in battery power you will need to get you through 7 days of rain.
You never want to drain a battery bank below 50% discharge so you need to double the Amp Hour of the battery bank.
Now you have your inverter size and your battery bank size.

Now you need solar panels. And you should put 10% rate of charge on the battery bank. But you have to keep in mind that you only have so many Peak Sun hours in a day. Some places get 4 and some places get 6 hours. You will have to keep this in mind when you size the solar array.

I still think grid tie with battery backup is the best way to go.

Here are a couple of links that will help.

This link has other links that will take you to more information on how to size a system.

http://www.oynot.com/solar-grid-tie-backup-by-array-size.html

Here is a design guide. Will take an hour or so to fill out.

http://www.oynot.com/media/design_sunwize_guide.pdf

Answer 2

Your electricity bill should tell you how many kwh (Kilowatt hours) that you use in a given period. If you have a year's worth of bills, so much the better. Take this information with you to the place that sells the solar panels, inverters and batteries, and have them work out what your requirements may be. They should take into account your locality, number of sunny days on average and the amount of power you need to draw out.
They should then be able to quote on how much a complete system would cost.

Answer 3

Wow! Nice project!

I haven't done it, but you would have to work out how much energy you use (you get that from your power bills) and then check out some solar panel manufacturer's websites.

I have feeling that energy consumption can vary a lot, depending on how you're set up, what you're running on electricity (hot water? heating?), so it would be hard to just throw out a number.

Answer 4

It will cost you thousands, or tens of thousands. You need to rewire your entire house using low voltage lighting, and you need storage batteries for when the sun isn't shining. You also need to get gas or propane water heater and refrigerator and do whatever you can to reduce you electric usage. You need to reduce to bare minimum anything that needs 120volts. This is often done in remote areas without public utilities available. Like hunting cabins.

Answer 5

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Answer 6

Yea there's a formula. But, suffice to say it takes a lot. Wind power might be better. [one turbine is aobut 1000GBP from B&Q]