Lower costs and simplicity of deployment will see the first heritage site in the UK to operate 100% off-grid continue to use lead acid batteries to store power generated by hydro and solar technologies, the National Trust announced on June 5.
The new system — a 48-volt, 24-cell architecture — uses a VRLA gel cell system from BAE with 30% more energy density than the original 48V battery bank, installed 14 years ago, using a Sonnenschein gel battery bank of 24 cells.
Chris White, technical consultant at Dulas, a renewable energy installer and consultancy firm, said: “The existing lead acid system has worked effectively for 14 years without issue.
“We chose lead acid because of its lower cost relative to lithium ion. It’s also simpler to connect lead acid to the existing battery charge controllers and battery inverters. There are some incompatibility problems with certain lithium ion batteries and charge controllers/inverters that we have experienced in the past.
“There is no space constraint on this site, and with the damp environment within the mill we considered lead batteries would be better. We also have greater field experience of using them relative to lithium ion.”
Work is due to be completed by the end of June.
Gibson Mill is a visitor centre at the Hardcastle Crags beauty spot in Yorkshire, at the edge of Hebden Bridge.
In 2005 Dulas was brought in to help make the site entirely energy sufficient.
This meant restoring the original Francis hydro turbine and installing a smaller Crossflow hydro turbine along with a solar photovoltaic system and battery system.