What are the items needed for 15 kW on Solar Power?

Question

I know that I need about 50 square feet of Solar Panels, but what should be the specifications for the batteries, inverters, charge controlers, etc.?

Answer 1

You need to do a lot of work.

There are contractors that will do it all for you.

Questions you need to answer:

Battery power or sell power to the power company?

How long must you operate when the sun is not out? Probably 20 hours at a minimum, 4 days at a maximum. Be aware that this quickly can bring the number of batteries up to a huge number -- that is the advantage of selling power to the power company, you can buy it back on cloudy days.

If you are not connecting to the utility company, what voltage and voltage purity do you need from the inverter? How are you distributing this power thruout the house? You cannot connect it to the house wiring, you will need a separate set of wires.

Do you have a place to locate the panels facing the sun? Be aware that even the shadow of a branch falling on part of a panel will reduce the output of a panel to almost zero.

If you are connecting to the power company, first see if they allow it, and see if the local and state laws allow it. See if they sell you the equipment, or do they allow you to purchase it, and if the latter, a list of suppliers.

the list goes on...

Batteries (no utility connection):

Batteries can be a major problem, which is why connecting to the utility company is a good deal.

If you want to store enough power for one overnight and one cloudy day, that's 36 hours. At 15kW plus losses that is 648 kW-hrs. A large sealed lead acid battery ($200-300) can store 100 amp-hrs, equivalent to about 1 kW-hr.

That totals 650 batteries, enough to run a submarine! Plus the room to store 650 batteries, plus the heat they generate, plus the electronics to control them. That is for one cloudy day, what about three!

This number of batteries is impractical, so you will need a backup diesel driven generator for those cloudy days.

How about storing power for overnight when the sun is out? still 16 hours in the winter, or 300 batteries. Perhaps you will use less power at night and can scale it down.

Now we get to the number of solar panels. I assume you got the number of 15kW from your power needs. but the panels have to deliver power for your immediate needs AND to charge up the batteries for night time use. With number of hours of sun as low as 6 per day, you will need 3 or 4 times that amount of power so you can store up power for the hours the sun is out.

you see the hugh number of trade-offs and decisions you have to make before you even start.

Answer 2

Look for "solar panels" on the Internet.  You will discover that 50 sq ft will give you nowhere 15 kW.  I have 40 full-sized panels, on my 6 kW system.  And a 6 kW rated system delivers only around 5 kW.

Read all you can find on the Internet and the green search box above before trying to make any decisions.

Answer 3

You are embarking on a project here.  You need to determine the level of power quality you are after.  To go completely off the grid takes a lot of effort.  You will need to do more research than you will find in answers found here.  Look in to the laws.  You might be able to make profit from un-consumed power if you sell it to the utility companies.  Many states have laws that if you produce more power than you use (beware that you still have to pay a service fee for utility connection) utilities are required to purchase it from you at the current exchange rate of whole sale power.

Research from creditable sites in needed.