Wasted energy: After the water in my storage tank reached 130 degrees, It was no longer being heated and the excess energy was being vented off the roof.  *Bermuda Sun file photo
Wasted energy: After the water in my storage tank reached 130 degrees, It was no longer being heated and the excess energy was being vented off the roof. *Bermuda Sun file photo

I’m writing this article on a lazy Sunday morning here in Bermuda after a night of fireworks, thunderstorms and heavy rains. The thunderstorms and heavy rains are not that unusual on a muggy July evening in Bermuda. 

As for the fireworks, it isn’t what you expect, considering it was the July 4th weekend.

I like to conserve energy on a Sunday morning. I like to make my coffee, sit out on the porch and finish off the Friday Bermuda Sun crossword and today was no different. The air this morning was heavy with humidity and the sun constantly obscured by those big puffy clouds that can bring sudden downpours, but each time the sun emerged from the clouds, the heat was on! 

By around midday, most of the clouds had retreated and I wandered into the laundry room to take the clothes that were washed overnight out of the machine and hang them outside to dry. Yes, as I’ve said many times, the old- fashioned washing line is without doubt the best value energy saving device available in Bermuda. The water that washed the clothes last night, fed the dishwasher and poured from my shower this morning was also heated for free by my solar thermal panel on the roof.

You could certainly be forgiven for thinking this all sounds like an energy conservationist’s perfect Sunday morning, and for many it would be, but not for me. 

When I looked at my control panel for my solar thermal system it gave me some information that I found very disagreeable. The temperature of the water in the 80 gallon storage tank was at 130 degrees, which I have set as the maximum allowable (anything hotter can easily scald), and it was only midday!

Midday to 3pm is what we consider to be peak solar hours, where the maximum amount of energy is available for harvesting. However, for the rest of the day my solar thermal system was going to sit on my roof and vent the excess heat it is generating to the atmosphere because the water is already at maximum temperature. 

In the summer months this is typical of ‘A Day in the Life of a Solar Thermal System’, particularly for those of us who are out at work all day and not consuming large volumes of hot water.      

By way of comparison, solar electric or photovoltaic (PV) systems start generating electricity as soon as the sunlight starts to hit them and they continue generating as long as the sun keeps shining. Unlike solar thermal, there is no pre-determined maximum, the more the sun shines the more electricity they produce. Better still, thanks to net metering, the electricity being generated can either be used immediately (if required) or sold back to BELCO to offset the cost of electricity being purchased at night when there is no solar electricity being produced by the system. 

Bermuda is a country with many limited and scarce resources, one of which is roof space that is suitable for mounting solar (thermal and electric) systems. Our cute cottage style architecture simply does not lend itself to large expanses of solar installations. As a result, we need to use the space we have as efficiently as possible to ensure we get the maximum return on our investment for any form of solar technology we purchase. Having a large, expensive, solar thermal panel occupying prime roof space and spending half its day literally ‘blowing steam’ is a very poor use of hard- earned dollars. 

That same roof space could be housing solar electric panels that are producing inexpensive, storable electricity for over six hours a day.

The electricity produced by the PV panels can then be used to power high- efficiency, residential, heat pump water heaters that typically use 70 per cent less electricity than traditional electric water heaters. 

A 50 gallon heat pump water heater can be installed for around $2,000 and will usually pay for itself in well under two years whereas a typical solar thermal installation is likely to be around three times that price and require five or more years to pay for itself. 

Your roof space is your ‘solar farm’ use every square foot as efficiently as possible to ensure you ‘maximize the value of your solar harvest!’ 

Nick Duffy is the divisional manager for Bermuda Alternate Energy.  Comments and suggestions to info@bae.bm