Hi Linda, this is really easy to do, but, and it a very big but. The Accenta is a pile of cack, and really suffer from mains failure's, so much so that that the surge from the mains coming back on just kills the panel. You wont find professional companies installing these, if a company is, then dont use the company. They dont care if your panel dies, they will just sell you a new one. The panel itself sold trade costs about £32 plus vat, It is very limited and basically rubbish.
Feel free to give me a call about the battery change
John 07842 480037
John, June 2009