Help needed for Solar Panel Hot Water system

Hi Everybody,

I just bought a house from a bank. It is forclosure. So there are many things we don't know about the house. The solar panel hot water system is one of them.

Here are some information of the system:

1. Storage Tank: SE62-80H-045S (a product from here, 6 years old);
2. Optimizer: Novan Energy FXB1000D Optimizer;
3. Solar Controller: CM-30 Solar Controller;

I am new to solar system. I have many questions on it:

1. How to adjust the hot water temperature? or how to control the hot water temperature?
2. How do I know the solar panel is working?
3. How can I make best use of the solar to minimize the electric usage? We use lots of hot water at night but not in the morning, how can we control the assisted electric will not heat the water at night and wait until next day's sun shine?
4. We live in Boston, MA and winter is very cold. Do we need to do anything special to make sure the pipes will not freezen in the cold wheather?

Anybody can help? Thank you in advance.

James