Solar Panels – The (Smallest) Footprint
We are often confronted with questions about the “greenest” way to generate electricity in the home. In doing some research on the embodied energy / carbon footprint of a variety of different solutions we came across a company in the UK who had done a very thorough analysis of their product. Rather than try to paraphrase their analysis, we asked Genersys Solar to provide an article for our site.
We are proud that Cellulose insulation has such a low embodied energy and we are looking to help homeowners save even more money and improve the environment. It looks like Genersys Solar is striving for the same objective.
Genersys Solar Panels
There are advantages and disadvantages with everything and solar panels are no exception. Until the day comes when energy is either not required or can be produced with no “side effects” we will constantly strive to minimize the impact on the environment.
Once solar panels are installed they provide benign and almost carbon free heat energy, which can be used to heat your water, your home, your pool and even to power heat exchange operations in air conditioning.
But we take it one step further. If solar panels are to be part of a low carbon energy future then it is important that their construction be as low carbon as possible and that the energy produced by the panels displaces the energy used in construction as quickly as possible. It is of course also essential that the panels are built to high standards so that they last for a long period of time, more like infrastructure than appliances.
At Genersys, where do our accounting in both monetary units and in units of emission saving. We have calculated the emissions that are created when we manufacture our solar panels and we can also calculate the emissions that our panels displace by using industry accepted simulations. In order to do this we have to first calculate the energy cost.
How much energy does it to make the panels, which comprise of aluminium, copper and glass, with insulation on some models, whereas other models rely on a vacuum for insulation.
The emission calculations have to take into account the fact that the energy used may be created by coal, or oil or natural gas or hydro electric power or nuclear power and the plants manufacturing the raw materials will have at different times different energy mixes, according to their local grid supplies, so it is impossible to be precise. What we have done, therefore in these calculations, is to use an average energy mix
Genersys uses aluminium for the panel trays and for the frames. The aluminium we use for each panel and frame costs 442.6 kWh of energy. The copper that comprises the meandering heat pipe and sensor pockets needs 108.4 kWh of energy to produce it. We use special glass and this makes up most of the weight of each panel. It uses around 100.9 kWh of energy. Insulation costs 19.4 kWh for each panel. Our own design of selective coating needs around 45kWh of energy to make it, and the additional materials uses 6.8KWh of energy. Therefore, the total energy needed per panel is 723.3 kWh.
We keep the manufacturing process as efficient as possible. By using our folding technology and not welding we have managed to keep manufacturing energy costs to around 45 kWh per panel. We also use energy recovery devices in manufacturing and recycle all our scrap and broken material.
Having established that energy needed per panel is 723.3 kWh we have to figure out what the carbon footprint is, using normal energy mix assumptions. 723.3 kWh translates into 137 kilograms of carbon dioxide per panel using a normal energy mix assumptions. In the UK most homes employ two panel systems which generally mean each system “costs” 374 kilograms of carbon dioxide for the panels and frames and for such things as transport, the peripherals (pumps station, controller pressure vessel and piping) probably add another 200 to 250 kilograms of carbon dioxide. This means that a UK default two panel system has left on average a carbon footprint of 600 kilograms of carbon dioxide.
To estimate the carbon savings we have to look at what is “displaced” in terms of carbon emissions by using solar panels. If the house is using power from a gas burning condensing boiler, the average two solar panel systems in the UK saves about 500 kilograms of carbon dioxide each year. Therefore the “carbon pay-back” of the solar system recovers the energy used in its production and installation in less than fifteen months.
If our solar system displaces oil as the fossil fuel it will save around 800 kilograms of carbon dioxide each year and will “pay” for itself in nine months. If the Genersys solar system displaces electricity it will displace around 1300 kilograms of carbon dioxide in a year “paying” for itself in about five months.
Our Slovakian factory has been making solar panels for over thirty years and many of the models made thirty years ago are still in useful operation. In the past thirty years we have made step by step improvements in the construction and durability of the panels. An example is folding the absorber plate around the heat transfer pipe instead of welding it as all other manufacturers do. We believe that in normal house installations the useful life expectancy will be in excess of 35 years.
Over a 35 year lifetime, depending on the fossil fuel displaced and the kind of water heating system being used, a two panel Genersys solar panel system in the UK will usually provide net carbon dioxide savings as follows:-
- Natural Gas 16,900 kilograms
- Oil 27,400 kilograms
- Electricity 44,900 kilograms
Therefore using a Genersys solar system over its lifetime costs the planet less than 10 grams per kilowatt hour when natural gas is displaced and less than 5gms per kWh when oil or electricity is displaced.
No source of energy is carbon free. Some sources, like coal and oil are carbon intensive costing around 800grams per kWh and 400 grams per kWh respectively.
Wind energy is low carbon when you take into account the maintenance regime that you need to adopt to keep the turbines turning comes out at around 8 grams per kWh. Photovoltaic panels “cost” in the UK around 58grams per kilowatt hour. Nuclear energy “costs” around 5grams per kWh, and even so called biomass between 35 and 90grams per kWh depending on whether it is used in co-generation).
Unlike solar thermal energy, the energy generated by wind and photovoltaic panels cannot be stored, so there are often times when the energy created by these is not needed and is wasted. The energy produced is also intermittent, which adds to the problem of creating the energy which cannot be stored when it is actually needed. Nuclear energy creates large amounts of dangerous radioactive waste which must be safely stored for around 10,000 years. Biomass can create carcinogenic smoke as a by product if the boilers are not meticulously serviced and the smoke washing apparatus not kept in good order.
Solar panels do not suffer from any of these disadvantages. They quietly and effectively generate safe carbon free heat which can be stored for the times when there is insufficient light without any adverse emissions or by products.
Closing the Lifecycle Loop
At the end of the 35 year life expectancy of a Genersys solar panel system virtually all of the materials can be recycled easily. Aluminium is easy and cheap to recycle and there are many aluminium recycling plants; in the USA for example, aluminium cans are the product that is most recycled. Glass recycling is very easy to undertake. Copper’s recycling value is so great that premium-grade scrap has 85% of the value of the primary metal from newly mined ore.
If important devices that create more environmental friendly energy (Solar Panels) and ones that save energy and the environment (Cellulose insulation) are widely adopted our carbon footprints would substantially diminish. The technology exists. The only question is whether we have the will and the foresight to adopt them widely.