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Q&As
Do I Need a Conventional Electricity Supply for my Eco Home?
My new build energy will be provided by Solarcentric solar panels, Tesla battery and an air source heat pump, which will hopefully take me off grid. Is there any need to have a conventional electricity supply connected as well? This would still incur a standing charge, which I am trying to avoid.
Thanks,
Amanda
3 Answers
Yes you will still need an energy supply. Your PV system, however large, will have very limited output in winter, which is when you will need electricity to power your heat pump for space heating.
You need to be aware that battery storage will help to get you through a 24 hour period – making daytime generation available for night time use. However, it does nothing to address the inter-seasonal mismatch between supply and demand in the system which you propose.
Batteries also have a very substantial environmental impact of their own, and this should be taken into account in your calculations. The identification of environmental impact as “carbon emissions whilst in operation” is a very narrow definition, and does not take into account all the other important aspects of sustainability, beginning with embodied emissions and pollution.
Bear in mind that, during the summer months, if your solar panels do generate excess electricity and your battery reaches capacity, you may want to sell energy back to the national grid, under the Smart Export Guarantee. You will need an electricity connection to do this.
Nigel Griffiths (Build It sustainability expert)
Hi,
I too am looking at building and going off grid and question the reply to this post. My solar array is planned as a 23 KW system with 23 KW battery storage. Using Solcast I have been monitoring my daily december/January forecasted solar energy production and see no reason why a system cannot be designed to run off grid.
I would appreciate more comment or information why this idea should be written off. With energy cost going ever higher this is a real ambition by many to avoid being trapped into the large energy companies.good luck with your plans Amanda.
Hi Michael,
The installation described (23kWp) is many times larger than the typical domestic installation (4kWp is often quoted).
If demand is very low, it might be possible to run such a system. I’m not sure whether you’re also planning to use a heat pump, but these do impose a substantial additional load and unless we’re talking about a Passivhaus or similar, then it’s unlikely to work.
It’s also important think about batteries and their environmental impact, as there are aspects which we need to consider other than just the cost of energy. If battery technology changes, then this could be revisited.
I hope this helps.
Nigel Griffiths (Build It sustainability expert)