Solar Power and Battery Storage

Hello and welcome to Just Have a Think. This week we're having to think about the largest nuclear reactor available to us human beings, you know the one we call the sun. It's impossible to really appreciate just how big the sun is compared to our own planet. To even get them in the same frame you have to shrink the earth right down to the size of a golf ball. Then if it was even possible to bring the sun down to earth without incinerating everything in its path you'd get something that looks like this. In fact you could fit a million earths inside the sun. Luckily though it's 93 million miles away which puts our little blue biosphere perfectly in what you may have heard referred to as the Goldilocks zone. Not too hot and not too cold. Nevertheless every single hour enough energy from the sun reaches the surface of our planet to power our entire world economy for a year. And unlike fossil fuels of course this particular resource has about another five billion years left to run. The challenge of course is to embrace and perfect the technologies we need to put in place in order to capture and use this energy in any kind of useful way. And that's where the solar industry comes in. Along with other renewable energies like wind, wave and geothermal, solar power is experiencing explosive growth all over the world. Especially now that battery storage has reached a point where it can be usefully combined with solar capture so that energy can be released to the end user whether it's sunny or cloudy and at night time as well as during the day. The amount of activity in this marketplace and the number of new and different types of technologies coming to market every week is mind-boggling and a bit overwhelming and way too big a topic for a single 10-minute program. I'll aim to bring you the most important updates and news as the weeks go by but just for the moment I want to focus on the domestic rooftop solar industry and how you can get involved. If you've watched one of the earlier programs called the Third Industrial Revolution then you'll know that I installed my own small DIY solar power system on an outbuilding in my garden last year. That went in pretty well so I decided to go ahead with the main grid-tied solar installation for the house. Here's the steps I took to find out what I needed and who to get to install it for me. Firstly you need a roof surface that points in a reasonably southerly direction. Like many typical Victorian terrace houses I've got two roofs at the back at right angles to each other. The back of my house is pointing more or less southwest so the sun comes across both roofs and gives each of them different amounts of sunlight at different times in the day. As usual when science gets involved you generally get fancy scientific terminology so this sunlight is technically referred to as solar irradiance and the amount your rooftop receives in a day is called solar insulation. This varies throughout the year of course as the seasons change but there are online calculators that can tell the average amount of sun you'll typically receive in your location and here's an example of one. Any properly accredited installer of solar photovoltaic panels should be able to do all those calculations for you so there's no need to worry about the numbers at the outset. As long as you've got a roof that's vaguely pointing in a southwards direction you should be fine. Obviously there are different sizes and types of installation. Here's a system that Robert Llewellyn, presenter of a superb YouTube channel called Fully Charged, had installed on his home last year and here's another system with panels sunk down flush with the roof line to be even more discreet. This one's featured in another excellent channel called EV Opinion and you'll find links to both those programs in the description box below. The next big decision to make is whether you just want solar panels on their own or whether you want to combine them with battery storage. If you choose to just have solar panels then the panels will be energy for as long as there's sunlight and that energy will be pumped into your home system for you to use as long as it's being produced. In a grid type system any power the panels are producing that you're not using gets fed back into the grid and you get a small fee for that which we'll come to later. This configuration without the battery storage obviously means you won't be getting any power on very cloudy days or at night time but if you've got a very active daytime household with washing machines and appliances going throughout the day then it might be the best configuration for you. In our household there's three adults all working through the day so other than a fridge freezer there's pretty much nothing electrical going on during the daytime in the week and then there's a big spike when we all get home and we're cooking tea watching tv and using tablets and pcs and what have you. So I chose a configuration that uses solar panels combined with a lithium-ion battery system and that way any solar energy generated during the day is prioritized towards charging up the batteries and anything after that gets fed back into the grid. You may have heard of the Tesla Powerwall which is designed to be a stylish addition to any interior or exterior wall as well as providing power for the home. Essentially it's a box full of batteries, these batteries to be precise, which are exactly the same batteries that power the Tesla electric cars. Tesla and their founder Elon Musk deserve great credit for massively raising the profile of renewable energy and electric vehicles and domestic solar power supply generally, but as I mentioned earlier the renewable energy market is experiencing explosive growth and there are quite a few alternative, possibly less sexy, power packs available. My decision to move to solar panels was really based on my mission to minimize my carbon footprint rather than any financial gain, but it'd be foolish to pay no attention whatsoever to the economics of these things, so let's have a look at the cold hard numbers. Bear in mind that the numbers I'm using here were relevant back in December 2017, but as you can see from this graph the price of the hardware is coming down all the time. The company that I eventually chose to supply and install my system are called ISO Energy. They're one of the most respected renewable and sustainable energy practitioners in the UK with very specific industry experience across all property types. Obviously other solar supplies exist so it's worth you doing your own homework, but I can say that the folks at ISO Energy were all extremely friendly, helpful, knowledgeable, and genuinely interested in moving the renewable energy market ahead, and I'll leave a link to their website in the description box below as well. ISO recommended a system of 10 300 watt panels which gives me a total peak output of three kilowatts, which they write down as 3kwp with meaning peak operating power. The cost to supply and install these panels plus inverter and all the necessary electrical cabling and safety cutoff boxes etc was about £6,500 excluding VAT. Now I made the decision to add the 4.8 kilowatt hour batteries because I felt that configuration suited our specific circumstances as I outlined earlier on. The cost of the battery storage system including the charge controller which does all the clever optimization of power to and from the batteries and to and from the grid plus the installation was about another £3,000 excluding the VAT. A really important point to note here is that you only pay 5% VAT on properly accredited solar installations, and if you buy your battery storage system at the same time as the installation then you only pay 5% VAT on that as well. But if you choose to buy your battery system at a later date then you will pay the full 20% VAT. Also another note of caution here, beware of websites telling you about great government incentives or grants for fitting solar panels. You don't get any grants or direct payments from the government for fitting a solar power system. The two incentive schemes that do exist are the generation tariff and the export tariff, and these are generally known as the feed-in tariffs or FITs. At the time of my installation which was December 2017 these schemes were paying 4.07 pence for every unit generated and 5.03 pence per unit as a general export tariff, which until the smart meters come online later this year is assumed to be 50% of all the electricity your system produces. So based on those numbers my projections look like this. The system is projected to generate about 2,800 kilowatt hours of energy each year. With the battery system I've got installed we'll be getting the benefit of all of that power. So based on 14 pence per kilowatt hour or unit that's a saving of £392 per year. As well as that we get a feed-in tariff payment of 4.07 pence for each unit generated, so that's another £113.96 per year. Then we get an export tariff payment based on the 50% assumption I mentioned just a moment ago. So that equates to a further £70.42 per year. So in year one we save a total of £576.38. Both of the tariff payments are index linked and your supplier should make the assumption in their calculations that that money will go up by 2% each year, which is basically inflation. They also should make the assumption that your electricity supply cost from the grid will go up by 4% a year, which I would say is a pretty conservative estimate. On the flip side they do have to build in a bit of inefficiency as the solar panels age and lose a little bit of performance each year, although that only goes down from 100% to 94% after 10 years. I will include a link to a full cost spreadsheet in the description box below, but essentially the payback on a system with just the panels and the inverter is about 10 years, and with my system with the batteries as well it's about 14. All rooftop solar installations these days will generally provide you with an app for your phone or tablet which is linked to the system's online monitoring portal. Here's mine. Bear in mind that my system got installed in the middle of winter and we're only just moving into the late spring and summer months now. Even so you can see that it gives you a very good idea of what you're saving. Having said all that, if your only motivation is money and you're after a quick buck from solar power then you really are missing the point. These systems last at least 20 years and probably a lot longer, so although you're looking at years and not months to recoup your initial outlay, after that your home's being powered for free for years to come. The cost of solar panels and batteries is tumbling all the time and it won't be long before we're all using electric vehicles, which will also add to the overall efficiency of your energy footprint. The future for renewable energy looks really bright if everyone who can adopt such systems does adopt them. There's even local cooperative groups springing up around the country to help neighborhoods share the cost of installing systems. Here's a recent example from Brixton. We're really concerned about the way money worked and about peak oil and about social welfare and they came together to try to figure out how they could work on a solar project but also to facilitate community involvement. Microgeneration that feeds into a distributed smart grid spanning the whole of Europe and eventually the entire globe is already well underway. One of the biggest fossil fuel producers, Royal Dutch Shell, were hit very hard by divestment and public boycotts back in the 80s during the battle to end apartheid in South Africa. Perhaps still mindful of how painful this experience was for them and even though they're by no means a paragon of virtue as a result, they have at least recognized that renewable energy is the future and they're making big strides to embrace the technology so that they don't get left behind. Other less open-minded fossil fuel providers around the world are still desperately trying to defame the renewable energy suppliers and deny that sustainable technologies are on an unstoppable march into their territory. The transition will most certainly not be smooth. The money that controls our world economy is unlikely to cede its territory without an almighty fight so we've got a tumultuous but probably quite exciting two or three decades ahead of us. Anyway that's it for this week. I do hope the program's given you some more concrete facts and figures so you can have a think about solar power for your own home. Please do click the red subscribe button if you haven't already done so and share the link with your friends so that we can get the word out to as many people as possible. As always thank you very much for watching, have a great week and remember to just have a think. See you next week.