A number of EV chargers have options for incomer current transformers, this way they can back-down the charge current to limit the peak load. I haven't seen this done often in domestic UK installs.
Yeah, same as my heat-pump.
But do you want to bet that if both the EV charger and the heat-pump monitor the infeed current, they're going to confuse each other mightily ?
I think it is important for the discussion that we all understand how much this is "per-country" due to political and technological history.
Even between the nordic countries there are huge differences, for instance in EV uptake or how much resitive heating is used, it has been almost outlawed in DK since 1973, whereas I belive it is still pretty much the norm in NO and FI (not sure about SE).
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But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
In any case, our eco-government is now paying a 2500€ subsidy if we dismantle working oil heating system and replace with direct electric heating; or 4000€ if replaced by air-to-water heat pump, which is what I did (haven't got my 4000€ yet, though). In any case, every air-to-water heat pump* revert to being simple direct electric heaters when the temperature drops to below around -20 to -25degC which is commonplace enough. This obviously coincides with when heating power is required the most; so now your 2.5kW input, 9kW output investment is temporarily just an expensive decoration which inputs 9kW to output 9kW.
The grid here mostly can take it no problem, but production is a big question mark, because for a some years now, Finland has been buying electrical energy from all neighbors. Gone are the days of buying from Russia and selling to Sweden. This winter, Sweden had close calls with their own supply and demand but thankfully were still able to sell us.
*) except a very few very expensive models, but even those won't have COP much over say 1.5 at such extreme temperature differential
The change is big, most homes built before 1990's use oil heating. Keeping existing, working oil-based burners as support devices for the few coldest days, still only contributing a few % to the total CO2 emission, would totally make sense. Most of the population live in areas where there are typically less than 5-10 days per winter of such low temperatures that air-source heat pumps have to rest (or work at ridiculously low COP say <1.5), but you need to design the whole infrastructure to be able to get through those days, and now suddenly we will have tens of thousands more households running with direct electric heating (so some 10kW). Which is 3x16A so you have 9A left per phase for everything else.
I don't agree that 35A circuits are required to charge an EV. I charge my model X from 120V, 1.4 kW. My situation is unusual, but nearly no one needs the full power of a 35A, 3 phase circuit (15 kW) for home EV charging.
I wasn't expecting to disconnect PE (though note it is now common for EV chargers to disconnect PE in the event of lost TNC-S neutral, yey for ugly workarounds).
I wasn't expecting to disconnect PE (though note it is now common for EV chargers to disconnect PE in the event of lost TNC-S neutral, yey for ugly workarounds).What the.. I design EV chargers and not aware of anything like that. PE bonding is one of the tests safety agencies do when certifying the product. Can you elaborate?
Here systems are mostly air to air and convert to resistance heating much below freezing, say -8 °C. That is in no small part because the systems are hit on both ends. A heat pump pushes heat uphill. Air to air requires more heat to be moved AND makes the hill larger. Air to water has a constant water temperature but requires more heat to be moved, so is less impacted by the outside temperature. By "air to water" I'm assuming you mean ground water, no? Buried coils in the ground or even a well pumping water for cooling?
The coldest days are typically clear (heat radiating into space). Residential solar can assist in those times.
Here systems are mostly air to air and convert to resistance heating much below freezing, say -8 °C. That is in no small part because the systems are hit on both ends. A heat pump pushes heat uphill. Air to air requires more heat to be moved AND makes the hill larger. Air to water has a constant water temperature but requires more heat to be moved, so is less impacted by the outside temperature. By "air to water" I'm assuming you mean ground water, no? Buried coils in the ground or even a well pumping water for cooling?
No, I mean air to water as in air is the source. Basically, take a bog standard air-to-air heat pump outdoor unit, but replace the indoor unit with plate heat exchanger releasing the heat to water. Why? Because now you can connect it to the existing central heating system. You can also store the heat in water easily, which is something not very trendy right now but nevertheless I'm doing that.
In air-to-water, low temperatures really hurt because unlike air-to-air where the condenser (indoor unit) has large surface area + fan and thus can keep producing fairly constant 25-26 degC air, air-to-water is usually connected to the existing radiator system which, even if generously sized, requires temperatures in excess of 45 degC so that the radiators give enough power output with natural convection. Best case, in-floor heating can work with lower water temperatures.
Pumping from -25 outdoor air to +50 central heating loop is quite a task to do; very best models can pull that off with COP near 2! But it's not worth investing 10000€ to do that if a 3000€ unit does almost the same except for the few coldest days.
Ground source is obviously ultimate in very cold climates and easy to design because the source temperature is constantly around +5 degC even in cold climates, given generous energy well sizing. Too small and it freezes though. Fairly expensive to install. Requires bureaucracy here. Typical install cost near 20k€.
QuoteThe coldest days are typically clear (heat radiating into space). Residential solar can assist in those times.
I have a 3kW PV system but the generation in coldest months - Jan and Feb - was exactly zero this year. You could clear the snow off the panels, yes, but the output would be still utterly minuscule, maybe in a good cold sunny day in January you'd get 3-4kWh and need 100kWh for heating that day. Now in Apr or May I get, depending of cloudiness, 20% to 60% of my heat consumption from PV, and this is with direct electric heating. With heat pump COP=3.0, this translates to 60% to 180%!
But the problem here is that Finland is an extremely dark country in winter, we have this thing called Gulf stream enabling us to somehow live here, but climatically equivalent areas in North America for example are much more down south, hence you have a lot more light there.
So it makes perfect sense to burn fossils during the two months of cold darkness and you can compensate during the remaining year.
3 kW is not a very large PV system at all. Not sure how your monthly generation could be zero however. Can you explain that a bit? Are you saying you live somewhere that the snow on the panels never melts for 60 straight days?
3 kW is not a very large PV system at all. Not sure how your monthly generation could be zero however. Can you explain that a bit? Are you saying you live somewhere that the snow on the panels never melts for 60 straight days?
Thick layer of snow for nearly three months straight. Normal here. Not every year for that long, but maybe every 3-4 years. Yes, you could remove the snow but it's not worth the hassle for maybe some 30 kWh/month generation. Later in spring, you get the same in two days.
Yes it's small, I dont't know why the previous owner cheaped out, there's room on the roof for many more panels and I'm sure the additional cost once the installers were on the premises would have been negligible. Anyway, I'm going to expand it. A 5-6kWh system, maybe up to near 10kWh now that panels are cheap, would be the sweet spot between investment cost and production. Too large and you produce excess power and need to sell it for cheap.
Here we have just to accept basically no solar generation for three months, but especially in springtime production is great and already a rather small 3kW system combined with air source heat pumping gives you almost full self sustainable energy!
Would you do better with vertical panels on a South facing wall,
I can highly recommend EU's PV estimator webapp: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html
Seems like both solar and heat pumps are rather marginal where you are. How many hours of sunlight do you get on Dec 20?
Would you do better with vertical panels on a South facing wall, would that be enough to be self-clearing?
Would you do better with vertical panels on a South facing wall, would that be enough to be self-clearing?
Not only self-clearing, but also in a pretty good angle for those winter days. Such installations can be seen here, it's generally a good idea if self-sustainability (i.e., energy production for oneself when it is needed) is the target. Yearly total production suffers significantly, but OTOH, does it make sense to produce excess energy in summer when everyone else is also producing in excess, and sell it for peanuts?
Sounds like a problem of locality of supply/demand. Doesn't your country share with others to the south?
my expectation is that maybe in 10 years, hourly rates are forced down our throats
But if the economics of production are unpredictable, if you have droughts or shortfall of electricity production, you cannot do that, and before you go back to issuing "milking-schedules", trying to make people think about when they consume is a good first step.
Yep. And it is a positive thing!
Is this still the thread about too high voltage in a home? Seems the kilt is tilted.