Posted 16 January 8 minutes ago, Krieg said: His intention can be providing a buffer for potential blackouts. If the blackouts is in a sunny summer day, the PV already provides (almost) all the electricity needed. And if it is in a dark winter day, the Akku is (almost) completely empty. Of course there are "in-between" days, that are both sunny AND you you buy a lot from the grid, but all in all they contribute very little, see my fig (yes of course, my case is mine, everybody is different...). By the way, how much do households suffer because of grid blackout these days...? Not sure enough to justify the cost of a 24kWh Akku (our 10kWh quote was 10keur). 8 minutes ago, Krieg said: Or maybe his wife likes to iron clothes at night. You never know. Could be. But my guess is that the most likely thing that happened is he didn't have access to better information and he came across cunny vendors. 0 Share this post Link to post Share on other sites
Posted 16 January 2 minutes ago, Gambatte said: By the way, how much do households suffer because of grid blackout these days...? This might potentially change. France, who is in a much better position in terms of energy that Germany announced many weeks ago about the risk of upcoming blackouts and told people to be prepared if such things happen. I prefer this approach compared to the Germans pretending everything is OK and thinking that looking strong and saving face is more important. Maybe it won't happen, actually most probably it won't. Fortunately the weather has been helping in the past weeks. Anyway, I prefer to do a decision by myself based on information available. 2 minutes ago, Gambatte said: Not sure enough to justify the cost of a 24kWh Akku (our 10kWh quote was 10keur). Could be. But my guess is that the most likely thing that happened is he didn't have access to better information and he came across cunny vendors. He is an electrician and he does the installations himself. I am sure he knows what he is doing. 0 Share this post Link to post Share on other sites
Posted 16 January 13 minutes ago, Krieg said: The motivation of having batteries is not always maximizing profit when things are running smoothly. His intention can be providing a buffer for potential blackouts. Or maybe his wife likes to iron clothes at night. You never know. I'd love a 24kWh battery. I work from home and when there is no electricity, obviously can't work at all. At the moment I only have a 2kWh battery/power station sat between the mains and the UPS connected to my workstations. The UPS kicks in after 1ms and the battery after 30ms. The battery can keep me going for at least 4 hours in case of a blackout. I'd love more capacity but it's an expensive game (€1k per kWh) for something which could potentially never be needed. I've also got a couple of mini batteries for running fridges/freezers in case of a blackout. They would also theoretically power the heating if needed. 0 Share this post Link to post Share on other sites
Posted 16 January 22 minutes ago, Krieg said: He is an electrician and he does the installations himself. I am sure he knows what he is doing. I am not sure. Electricians I came across in my life are great folks and excellent at all they do, for example installing Akku etc. (actually not every elctrician can, needs specific additional qualification, which he could well have) But their skillset I'm afraid doesn't always include collecting data and running math. In fact, I bet it almost never does. 17 minutes ago, Eric7 said: The battery can keep me going for at least 4 hours in case of a blackout I could be wrong, but a full 24kWh would last you MUCH longer than 4hr. And most likely, depending of course when the blackout takes place, the 24kWh would be (almost) completely empty at the start of the blackout. On average, we consume 2400 / 365 = less than 7 kWh/day The MOST we ever consumed in the last 3yr in a single day was 10kWh, it was the day I made 100 jam jars (cooking, sterilizing all glass jars in the oven, then running them again in boiling water once filled and closed). 100 jam jars takes a very very huge amount of energy. Of course this is my case, everybody's different. 0 Share this post Link to post Share on other sites
Posted 16 January 3 minutes ago, Gambatte said: I am not sure. Electricians I came across in my life are great folks and excellent at all they do. But this I'm afraid doesn't include collecting data and running math. You don't even know his motivations and you are already saying he is wrong, he didn't do that math an so on. And the best, he does not need such big battery. You are starting to sound very German to me. 3 minutes ago, Gambatte said: And most likely, depending of course when the blackout takes place, the 24kWh would be (almost) completely empty at the start of the blackout. If your battery is your emergency backup you would setup your system in a way that it is always almost full. Letting the battery deplete for financial reasons would make no sense. 24kwh cost peanuts (financially) but they might become invaluable in a rough situation. 1 Share this post Link to post Share on other sites
Posted 16 January 5 minutes ago, Gambatte said: I could be wrong, but a full 24kWh would last you MUCH longer than 4hr. And most likely, depending of course when the blackout takes place, the 24kWh would be (almost) completely empty at the start of the blackout. No, the 2kWh battery will last me at least 4 hours. It's always full at the time of a blackout because it's connected to the mains. The power just runs through it once it's full. 7 minutes ago, Gambatte said: On average, we consume 2400 / 365 = less than 7 kWh/day The MOST we ever consumed in the last 3yr in a single day was 10kWh, it was the day I made 100 jam jars (cooking, sterilizing all glass jars in the oven, then running them again in boiling water once filled and closed). 100 jam jars takes a very very huge amount of energy. Of course this is my case, everybody's different. I averaged 50kWh per day last year. I've since replaced 10 workstations with just a couple of much more efficient ones. 0 Share this post Link to post Share on other sites
Posted 16 January 4 minutes ago, Krieg said: you are already saying he is wrong did I? 0 Share this post Link to post Share on other sites
Posted 16 January To be prepared for a blackout I'll simply buy a diesel generator. Much cheaper than backup batteries. 0 Share this post Link to post Share on other sites
Posted 16 January 13 minutes ago, jeba said: To be prepared for a blackout I'll simply buy a diesel generator. Much cheaper than backup batteries. But the generator has to constantly run, even for something that requires very little power. I've got a generator as well & it can fully charge the biggest of my batteries in around 30 minutes. Then it can be switched off and I can run things off the (silent) battery instead. 0 Share this post Link to post Share on other sites
Posted 16 January 19 minutes ago, jeba said: To be prepared for a blackout I'll simply buy a diesel generator. Much cheaper than backup batteries. Sure, very effective. If you do not have to run electronics from it. And it will have to be running all the time, or you have to keep switching it on and off, while batteries work on demand. And you will have to run it outside your house or die of CO2 poisoning and wire it somehow inside the house. And after two minutes your neighbor will come and complain about the noise, because Es ist Deutschland hier. Do not get me wrong, it is as well a good tool, and while they both kind of do the same, you are comparing apple and oranges. P.S. Actually most cheapish generators run on benzine, not on diesel. Diesel ones are expensive, as far as I know. P.P.S. Benzine generators with pure sine wave (so you can use them with electronics) do exist, but they are not cheap. P.P.P.S., But to be fair, there is a new wave of such generators at reasonable prices, but they are mostly "Ali Baba" products, made in China, with no one knows which quality and safety. Some in paper look quite good and the price is actually reasonable, some even include modern features like Bluetooth control. But I wouldn't trust those things until someone else test them properly. 0 Share this post Link to post Share on other sites
Posted 16 January Getting back to saving energy... On Saturday I purchased a pack of three motion sensor lights from a well-known discount store. My motivation for this comes from looking at what I had been doing when coming home to an empty house - first I would put on the main living-room light, so that it would also light the entrance hall. Then I would switch that one off and put on a single light in the living-room so that I could pop into the bathroom, get the bath running, and come back to get my towel from the radiator. in the meantime, I would have also popped into the kitchen, switched on the light, and rummaged around in my basket to get the things that I need for the evening/overnight, that I would take into the office, where I would use the light of my mobile phone to find the plug socket to plug the light into and then switch it on. Obviously, the bathroom light was also on for most of this time. Anyway, since I read that most of the energy is used in actually switching on lights, I thought it might be a nifty idea to just not do so, and thus the motion sensors.... after two days of use, all I can say is that it is very convenient not having to find the light switch in every room as for the long-term possible savings, I am not sure how much I am saving, if at all, but I thought it would worth a try! 2 Share this post Link to post Share on other sites
Posted 16 January 16 minutes ago, robinson100 said: On Saturday I purchased a pack of three motion sensor lights ... How much power do the sensors use? They're now going to consuming a little bit of power 24 hours a day. It's standby mode for lights. 1 Share this post Link to post Share on other sites
Posted 17 January 17 hours ago, Krieg said: P.S. Actually most cheapish generators run on benzine, not on diesel. Diesel ones are expensive, as far as I know. You can get diesel generators at reasonable prices ( at least compared to batteries). E.g. this Japanese 15 kW for € 2300 (in Cyprus, where prices are usually higher): https://m.bazaraki.com/adv/4244296_generetor-15kv/ 0 Share this post Link to post Share on other sites
Posted 17 January 51 minutes ago, jeba said: You can get diesel generators at reasonable prices ( at least compared to batteries). E.g. this Japanese 15 kW for € 2300 (in Cyprus, where prices are usually higher): https://m.bazaraki.com/adv/4244296_generetor-15kv/ I think my definition of "reasonable" is different to yours. Anyway, feel free to buy one if it fits your requirements. AFAIK this discussion is moot point because you are just arguing for the sake or arguing and you are not going to buy anything. 1 Share this post Link to post Share on other sites
Posted 17 January 4 minutes ago, Krieg said: AFAIK this discussion is moot point because you are just arguing for the sake or arguing and you are not going to buy anything. I've already bought a cheap Chinese one which broke down after 2 weeks. Now I'm probably going to buy the one I linked to as soon as my broken leg will allow me to drive again, so I can see and hear it running. 0 Share this post Link to post Share on other sites
Posted 19 January On 1/16/2023, 2:30:40, Gambatte said: If the blackouts is in a sunny summer day, the PV already provides (almost) all the electricity needed. Without a battery a solar installation don't really operate off-grid as people might think, even in a sunny day. The production of electricity is not steady in the long term. Your appliances that need decent steady amount of electricity will keep switching off and on. Example: You take a single 100w solar panel in a sunny summer day, you set it up at the best angle and you use a MPPT solar controller. So you have now the most optimized setup. When the sky is clear you will produce around 80w, maybe 90w if it is a high quality panel. Now you connect a fridge what needs 50w. You would think your setup is enough, but in reality it is not. Clouds will move around and your system will produce anything from just a couple of watts to again back to the max. Once your production is below 50w the fridge will go off. The more the clouds move the more you will have this effect. And clouds move a lot. People make the mistake of taking the total solar production of a day or a month and compare it to their total consume in the same period and it is not as simple as that. P.S., And it is a general misconception that home PV setups work during blackouts. In most cases they won't because the inverter won't work without a reference current. Some might work if they have batteries and they are configured to do so. 2 Share this post Link to post Share on other sites
Posted 20 January 22 hours ago, Krieg said: People make the mistake of taking the total solar production of a day or a month and compare it to their total consume in the same period and it is not as simple as that. This is true, but your example refrigerator also cycles on and off. So the X watts for the refrigerator is not constant. Smart would be to have appliances know what the battery/sun has available (or cost of grid delivered) and decide whether or not they can delay a cooling/washing energy using cycle. 0 Share this post Link to post Share on other sites
Posted 20 January 37 minutes ago, mako1 said: This is true, but your example refrigerator also cycles on and off. So the X watts for the refrigerator is not constant. Smart would be to have appliances know what the battery/sun has available (or cost of grid delivered) and decide whether or not they can delay a cooling/washing energy using cycle. The fridge cycling is irrelevant to my point, but yes, fridges cycle. Change it for a 50w light then. Your idea sounds good in paper, but I don't think it will work. It is extremely complicated to predict when the sun will be covered by clouds. If you really care about costs, the real optimization is minimizing going through the battery and using your solar energy as much as possible instead of selling if for peanuts. Easy to say, difficult to implement. Maybe it will be possible in the long future when AIs can process complicated scenarios with so much entropy like this. 0 Share this post Link to post Share on other sites
Posted 20 January There are some manufacturers that provide an emergency backup in the event of a power cut. The system cannot provide much current in this case, but Fronius mentions 3kW available to a specific socket in the house. I reckon most people would choose the fridge rather than a phone but ok: https://www.fronius.com/de/solarenergie/installateure-partner/produkte-loesungen/features/notstromfunktion The thing about clouds is, they do pass, so if I look at the weather forecast for a July day and it says sunny, I can run my 4 hour eco dishwasher programme and most of the power will come from the PV array. The few minutes of passing cloud will not change that. It's about percentages rather than absolutes. It's ok if my dishwasher pulls 10% of the electricity it needs during that cycle from the mains because of passing clouds. It will seamlessly do that. If the production goes low in those moments, it wasn't available so nothing is "lost to the grid" I do take the point that total PV production is impossible to use without storage (which at present doesn't add up, but I believe it will when more and more used car batteries end up as poor man's Tesla walls still with 70% capacity in them) but you can play the odds by looking at the weather forecast or even looking out the window. Clear sunny day? Run that washing machine! Overcast but the forecast for tomorrow is for sun? Wait 24 hours! 0 Share this post Link to post Share on other sites
Posted 20 January My example with the fridge is not a theoretical example. It is a real life example in our van. At the end I run the fridge from batteries, even during the day (because on top of that our old fridge would go into error mode if there is very low amperes and low tension, it will think the "battery" is way too depleted). I bought a very good solar controller to study how all this works, it is a Victron, they make amazing products. It produces very good data. OF course, if you are connected to the grid, you will always have the needed power to run your devices and nothing will be "lost" at that specific moment. My whole point is to describe how really solar panels work. The example from your link it just adding a battery to the system. Totally agree with the poor man's Tesla wall. But Es ist Deutschland hier, I bet it will be forbidden, or you will have to get an approval from TÜV that costs more than the battery. Just check the legislation for "Balcony Solar Installations". In the mean time I will be pissed seeing in Youtube how everyone in UK is installing an old Nissan Leaf battery at home. 0 Share this post Link to post Share on other sites
