Mana Energy

We want to be off grid but in the first phase we will have a connection to the grid to supply electricity. It will be interesting to see whether we do eventually go off grid given that we might find the grid solutions to be more interesting than off grid. The idea of having solar and wind power balanced by a storage battery that together can help balance the load on the grid has growing appeal. With innovative tariffs it’s now possible to trade in electricity with a battery, and using cheap import rates overnight and high export rates at peak times we can help ourselves as well as the environment. One of our challenges, given our low usage of electricity is how to justify the expense of a battery. Without these new tariffs there wouldn’t be a pay back.

We’re going to start out with a 4.5kW solar pv array on the roof, connected to a 5kW battery. We’ve researched the amount of electricity that we use and how much we can get from the solar panels across the seasons and have sized it accordingly. We will have surplus in the summer and will export to generate some income, and in the winter we will trade with the grid by importing overnight to the battery and selling during the peak demand in the late afternoon.

We’ll be using electricity for heating, hot water, cooking, washing machine, fridge and computers. The hot water and heating will be serviced by a hot water tank with an integrated Air Source Heat Pump. These tanks come as an integrated unit and so installation is very straight forward, just cold pipe in, hot pipes out and an electricity connection. Our needs are not great and we will go for a tank size of around 1,000 litres.

We would ideally like a wind generator but the products are not yet reliable enough. There is a Spanish company developing a generator with no moving parts which would mean high reliability and no hazard for birds, but for now we’ll wait. The idea would be that there is more sunshine in the summer (solar pv) and more wind in the winter (wind generator), but the smart tariffs might prove a better bet, we’ll see.