Are Solar Diverters No Longer Worth It?

so you're thinking about using a solar diverter to heat your water instead of using fossil fuels I mean why export your excess solar when you can save money on water heating and save the planet at the same time well actually I think for a lot of people now a solar diverter doesn't make Financial sense anymore and depending on where you live it doesn't make sense environmentally either stay with me and I'll explain why [Music] foreign [Music] hi I'm Gary and welcome back to my channel Gary does solar so you have a solar installation and it's a sunny summer's day you're generating far more than your home appliances need right now we're all taught the golden rule of self-consuming every kilowatt hour of solar you generate this saves you from buying those kilowatt hours at your standard rate which will cost you much more than what you would be paid if you export it so what kind of things can you do with excess solar then well having a battery allows you to store your excess until later in the day when the sun has gone down at this point the battery can power household appliances until it runs out you'll find though that on a sunny summer's day it won't take very long to fill your battery so you'll still have access if you have an electric vehicle you can charge it and EVS have large batteries so could easily take all of your excess solar if you have a water cylinder you can heat your water with excess solar instead of using gas or other fossil fuels and if you have washing to be done whether that's your clothes or your dishes you can get all of that done using your Excel solar air conditioning systems are perfect for solar excess they are generally running when the sun is shining and many people with solar are considering adding AC to their properties because of this and finally if you own a hot tub or pool using excess solar is a great way to keep those at temperature now all of these options all make perfect sense well apart from this one actually I'm going to make the case that heating your water using a solar diverter is not as financially lucrative as it was even just a year ago and it might not be as environmentally friendly as you might think either let's first have a quick recap on what a solar diverter is and how it works here is a typical water cylinder that is present in many homes if we look inside we can see a cold water feed coming in at the bottom which keeps the cylinder full of water then to heat that water there's a hot water feed coming in from your gas or other fossil fuel boiler which transfers its own heat into the water inside the cylinder until the desired temperature is reached hot water can then be drawn out the top of the cylinder at any time which is replenished by more cold water coming in at the bottom crucially the water cylinder also contains an electrical immersion heater this can be used as a backup in the event of a gas boiler failure a solar diverter is a small unit that sits in between the electrical supply switch and this immersion heater with the switch on it will power the solar diverter but the immersion heater itself receives no power the solar diverter is able to monitor a solar installation in order to detect excess solar and when that happens this excess is diverted into the immersion heater for a more in-depth introduction into solar diverters please take a look at this video I made a few months ago I've put a link to it in the description you might buy a solar diverter for two main reasons Financial benefits essentially saving money on your gas or other fossil fuel Bill and environmental benefits essentially reducing your carbon footprint let's analyze the financial benefits first and get ready to be surprised when I released my solo diverter video I also provided a utility to go with it you can quickly try out that utility on any mobile device by simply scanning this QR code you can also access it via the link in the description the utility allows you to calculate how long it will take to get payback on the solar diverter based on a number of criteria it defaults to a family of four with an average usage of hot water if we use today's cost for electricity and gas in the UK you can see that for a solar diverter costing around 535 pounds including installation you could expect a payback in just under 2 a half years and this figure assumes a solar export rate of 4 Pence per kilowatt hour in other words covering the income lost from exporting the same energy instead if you don't get any income from exporting solar then the payback period drops to just over a year and a half now that four Pence per kilowatt hour for exported solar was considered a pretty reasonable figure a year ago but since then export rates have gone up substantially and you'll see in a moment that this just kills the financial case completely look what happens to that payback period as I slowly increase the export rate by the time I get to 12p the payback period is over 22 years and at 13p the utility decides that you will never get payback and look that's even if the solar diverter was provided to you and installed for free let's see then what's actually happening in the market today with solar export rates here are the latest export rates in the UK which have increased quite a lot in the last few months you can see that the top four tariffs highlighted in green completely destroy the financial case for a solo diverter you'll make far more money exporting that excess instead even if you live outside the UK it's worth checking to see how export rates might have increased in your own country in recent months you could well be surprised the top two rates in this table are provided by octopus energy and if you're not already a customer I strongly recommend them as a provider even better if you use my referral code here when you join we'll both get 50 pound credited to our accounts a huge thank you to all of you who have helped me in this way it allows me to keep making more and more videos for you so in light of increased export rates there's no longer a case financially to get a solo diverter but you may still want to get one for environmental benefits so let's consider those now heating your water with free solar electricity has to be far better for the environment than burning gas or other fossil fuels yes well I have to say what you're about to see surprised me a little depending on where you live using excess solar to heat your water instead of exporting it may actually cause more fossil fuel to be burned this seems strange I know but let me take you through the reasoning let's assume your solar installation is generating excess solar energy you have a choice you can divert that energy to a solar diverter and heat the water in your cylinder or you can export it if you choose to export someone most likely a neighbor can immediately make use of that energy in their home for example with a vacuum cleaner but you'll still need to heat your water and if you're not using your excess solar to do that you'll likely have to use fossil fuel let's assume a gas boiler in our example If instead of exporting you choose to divert your excess solar to heat your water then your neighbor will need to power their vacuum cleaner from another source now here is where I couldn't make up my mind where that grid energy would come from here is a typical Supply mix for electricity generation in a country this one is based on the UK you start with nuclear as you can't easily switch these plants off they're always generating power then you add in hydro and other renewable generation as these are the cheapest and finally you make up any shortfall in demand with fossil fuels and these are the dirtiest and most expensive fuels so with this Supply mix in mind with the power for your neighbor's vacuum cleaner come from Scenario a marginal generation like coal or gas to make up for what would have been exported energy that is no longer there or scenario B would it randomly come from one of these sources in which case we'd be looking at the total percentage of fossil fuels in the mix to determine the chance that the energy came from there now I don't know for sure which of these two scenarios is more accurate maybe you could let me know your own thoughts in the comments how about we look at the impacts of both scenarios then starting with a let's start by adding some numbers into the diagram so we can do some calculations perhaps you have one kilowatt hour of excess solar generation and here you've chosen to divert it so a hundred percent of that generation goes into heating your water If instead you heated that same water with gas you would require more than one kilowatt hour of gas because gas boilers are not a hundred percent efficient if we assume let's say an 80 efficiency then you would actually require 1.2 kilowatt hours of gas we can now consider the energy requirement of your neighbor then let's say their vacuum cleaner has a power rating of one kilowatt and runs for an hour their requirement is one kilowatt hour of energy but because you're diverting that solar instead of exporting it your neighbor will instead need to get that one kilowatt hour from another generation source and in scenario a this would be from marginal generation in other words a fossil fuel source if a gas or coal plant is used to create that one kilowatt hour then we need to also consider the efficiency of that plant and today they are typically only around 50 percent efficient so that plant would need to burn two kilowatt hours of gas to replace the export that you would have otherwise provided to your neighbor so in scenario a using these figures if you divert instead of exporting although your personal carbon footprint has reduced overall you're actually causing sixty percent more fossil fuel to be burned the very opposite of what you intended so exporting is better and you're getting paid for it at the same time okay let's look at scenario B now in order to work out the gas requirement we need to find out for the country you live in the percentage of electricity generation that comes from fossil fuels this varies across the world but I found this handy website which has all the information in one place in 2022 the USA had just over 60 electricity generation from fossil fuels and as you can see this level hasn't changed all that much over the last 40 years Canada is doing really well at only 18 and this has been dropping at a constant rate over the last 20 years they have a lot of hydro the United Kingdom is higher at 45 but this has been dropping sharply over the last 20 years Germany 51 percent France very low at 12 percent but remember they have a lot of nuclear generation Spain 37 and steadily declining due to solar Italy quite high at 64 percent with no real change over the last 10 years China 66 is slowly dropping over time India quite high at 78 percent with no change at all in the last 40 years Saudi Arabia perhaps no surprise at nearly a hundred percent with all of their oil and Australia 71 with high coal usage but slowly coming down you can also see the changes over the years by adjusting this slider feel free to use this website to see what's happening in your own country by my calculations as a Rough Guide if the electricity production from fossil fuels is 50 or less then you won't be causing any more fossil fuel to be burned by diverting but depending on the actual percentage you won't be preventing as much fossil fuel from being burned as you might first think either I've summarized all my findings in this diagram here if you're primarily financially motivated and your export rate is less than 12 Pence per kilowatt hour and you have high water usage meaning four or more people in the household then diverting is worth it but as you've seen export rates are climbing all the time and there are several tariffs in excess of 12 Pence per kilowatt hour meaning that exporting is worth a lot more and if you're motivated more by the environment with scenario a you're always better exporting and with scenario B If the percentage of fossil fuel used for electricity generation in your country is 50 or less then diverting is better thanks for taking the time to watch this video and hopefully it's got you thinking please don't forget to like And subscribe and I'll see you very soon in the next one [Music] foreign [Music]

Channel: Gary Does Solar

Views: 10,816

Keywords: solar, diverter, water

Id: 6zc1g1bz0eA

Length: 12min 21sec (741 seconds)

Published: Tue Mar 07 2023