So when you say “harnessing electricity” three things come to mind- generating electricity (wind, solar, fossil fuels, etc), batteries (harnessing in the sense of storing), and early investigations into what electricity actually is and how it can be used (Benjamin Franklin’s kite experiment, Nikola Tesla’s work, etc). Here are some resources for each topic:
A write up/timeline about Ben Franklin’s experiment:
documents Franklin.

General history of electricity: this is a quick read, but touches on many topics of electricity (science, politics, economics, etc.) So depending on which sparks your interest, you can follow the references on each topic.
history electricity.

Nikola Tesla:
He did a ton of interesting experiments (including trying to transmit electricity through the air!). He is most known for developments in alternating current- which is the primary form of electric current you use in your day to day life.

Wikipedia has a list of a bunch of Tesla works: Tesla work.

Here is an interesting documentary about him:
Tesla documentary.

Batteries: If you are at all interested in batteries, I recommend you glance through the following books- they are a bit lengthy, but they will tell you everything you ever wanted to know about batteries and then some. They are the Principles and Applications of Lithium Secondary Batteries and the Handbook of Battery Materials. These are pretty standard texts/resources in the battery industry.

Generating electricity:

A brief summary of electricity sources since 1950: electricity in the us.

A report from the National Renewable Energy Lab (NREL) outlining the current state of our energy supply: admittedly this is a bit tedious, and I know you asked for early studies on harnessing electricity, but this baseline report is a pretty good resource for someone interested in the area, so I figured it couldn’t hurt to share.
energy supply.

Electricity revolutionized the way we live, which is why early experimenters in electricity are famous. The scientist who discovered electromagnetism was Danish physicist Hans Christian Ørsted, and the concept was first demonstrated in an electric rotation device called the electric dynamo (the ancestor of the electric motor) by British scientist Michael Faraday. Faraday would later discover the concept of electromagnetic induction, which inextricably links the phenomena of electricity and magnetism.

Induction refers to the electric current generated in a conductive object, when the electric or magnetic field created by a nearby object is changed (e.g. by movement in space). Electromagnetic induction is the principle behind modern electric devices including motors and transformers. Below is a link to an online version of Michael Faraday's work circa 1855, in a book with an introduction by his contemporary John Tyndall, published in 1914. It is called: Experimental Researches in Electricity . The journal entries of Michael Faraday are in the archives at the Royal Institution .

Earlier work in electricity from the 15th century involved static electricity: rubbing amber made objects become attracted to it. The English word electricity comes from the Greek word elektron, meaning "like amber." Here is a link to the online version of the first known published use of the word "electrical," in Sir Thomas Browne's encyclopaedia, Pseudodoxia Epidemica, or, Enquiries into Very many Received Tenets, and commonly Presumed Truths from 1672. It covers many topics, but for electricity, see Book 2, Chapter IV: here.

Yes! I saw a show about the battle between Tesla and General Electric about whether to have DC or AC power - war of the currents

You can google this: tesla ge ac dc. There are hits from history.com & energy.gov & science.howstuffworks & etc; there are lots of videos about it, too.

I googled: history of electricity There's this: electricity history & this: history electricity & lots more.