PV Gap

Violet Said:

What are the parts required for a 10 kWh rooftop solar system?

We Answered:

Hey Steven, J is right about the power companies possibly offering to subsidize an installation such as this, but I'm curious, why 10-50 kw? (I assume you mean kilowatts, not kilowatthours). That is a very large system, our home runs on a 1.4 right now, and in most cases, if you plan on intertieing your system to the grid, it has to be no larger than what you would normally use on sight. In most cases, if you generate more at the end of the year then you used, the utility company keeps the excess. With a 10 kw solar array, you would probably be giving 6 kw away for free. Remember, there are two ways to get funding outside of your own wallet. One is going through the power company if they have a subsidy program, the other is to purchase your system, and use any tax incentives, grants or write offs you might qualify for. You can't do both, if the power company is buying you a system to pay back on using their money, it is their tax write off now.

As far as the equipment, you have two options. One is the intertie, in which case, you need the panels, disconnects (one at array, one in control room) and the inverter. Using a direct solar to grid inverter negates the need for batteries, since the grid is your battery, and charge controllers, since you are not charging a battery. It is cheaper and simpler, but one drawback that is not usually considered is that if the grid goes down, your system goes down with it. You will not be able to access your solar array to run your own home even if it is sunny. The few times this happens to people with grid tied systems, it can be very frustrating. If you decide not to grid tie, you'll need at least a small battery bank (figure $500 minimum) and a charge controller in addition to the list above. Good news is you can run your house on this system if the grid fails.

J mentioned positioners, I think he meant trackers. They add some cost, but more production by turning the panels during the day to capture more sun. Generally they pay for themselves in a few years through higher production, or fewer panels to make the same energy, but you can't use them on the roof, they are ground mount only. Most roof mounted systems use a simple rack that many people build themselves for just a few dollars. You can get premanufactured rack systems for a little more money, easier to install.

What I'd like to add is that there is a great deal more miscellaneous bits and pieces to something like this that you won't be able to get through a forum like this. You either need to take some more time to educate yourself on this subject, or hire a professional. We did our own installation 11 years ago, except for our wind turbine tower, and we spent a year going to energy fairs and reading publications. Still we made a few mistakes. You can't pick up this stuff at Home Depot and put it in on a Saturday afternoon, and there are plenty of places willing to ship stuff to you for a price, even if it isn't what you need. My suggestion is check out the sources below, get a subscription to Home Power, and get to one of the fairs. It won't cost much, and you'll be in a much better place to make a decision in the end. In the end you might decide not to get involved at all, and that's fine, but at least you will be well informed. Take care Steven, Rudydoo