Victron or Lux

[Fintray]

You should have a look at this thread as it may answer some of your questions https://camelot-forum.co.uk/phpBB3/view ... 314#p12314

[sharpener]

Thanks for the responses boys and girls.

Another related question, I have a 3.68 KW grid tied PV system and plan to use excess capacity to charge batteries via a Vectron.
If I want an addtional PV array, could I avoid the installation of another Inverter and use an MPPT charger to the batteries direct and hence use the Vectron inverter to convert back to mains voltage. This would mean that both the existing and the new system could charge the batteries and this would mean importing less electricity particularly during the winter.

If this is possible, then when I make my G99 application then I only need to quote the existing 3.68 KW inverter and the Vectron inverter 5KW (3.68 + 5 = 8.68KW ) if I can't do it this way then an extra PV system will need its own inverter and hence I will have to apply for (3.68 + 5 + new system 4 kw= 12.68KW)

I suspect that Northern Power Grid are more likely to approve 8.68 KW than 12.68 KW

Anybody know what is possible ?

I first tried this with Western Power but they didn't understand/didn't like the extra solar panels charging via an MPPT (I was proposing a Victron EasySolar which has it all in the one box). So I split the project and just applied for the existing 3.68kW PV plus a new Victron 5kVA MultiPlus on the standard G99 route which was successful. Even though it has a G100 ELS they want the MultiPlus turned down to 3.7kW inverter power as well, which I am happy to do because the battery limits it to that anyway.

Hope you have better luck/more flexibility on the part of Northern Power.

BTW the 5kVA Multi has a continuous rating of only 4 kW in grid-connected mode (but it is 4.4kW in off-grid for some reason). However WPD said they were mostly concerned about its surge capability before the ELS kicks in, which is theory is 100% i.e. 8kVA.

[billi]

Just a general question or findings

The Victron Quattro 5 kVA (or Multi) with its toroidal transformer and the power-assist feature

So if the PV produces via GTI 2500 watt or so , those are added onto the total available power , and if needed the grid can power- assist in parallel too .

So the question i have , is this an feature the other inverters we talk about here do share ?

[Krill]

The Victron of that size will be G99 and not G99 fast track as its over 3.68kW of inverter power. But if you want the power, don't let doing a G99 application stop you, some people have found the process just as easy.

Also "Greenlinx" is just a trademark registered with Infinity Innovations Ltd who trade under various guises, who knows what the actual battery manufacturer is. i.e., its likely to be a re-badged jobby so I would take specifications with a pinch of salt, with Pylontech, you know what your getting.

EDIT - I suspect the "Greenlinx" battery might be a "Aobo Uhome 2400 battery".

New poster, newbie in every sense of the word with regards to Solar PV. Been lurking the forum for the past few days to learn but sometimes you just have to ask questions.

I'm looking at a 6.4kW, 16 panel rooftop installation on a south facing roof and having everything commissioned in a single go: hybrid inverter and batteries. The conclusion I keep on coming to is that I need 2 inverters to manage the issue with peak use as I have 4 refrigeration devices (batch cooking and storing food for multiple other older family members when I do their shopping every week). For context 2 adults working from home with lots of monitors and laptops and future plans involving an EV.

Are there any known issues with the "Greenlinx" batteries? As great as the Pylontechs are reported I haven't found anywhere that has them available. And the Squirrel pod quote I got blows everyone else out of the water even considering it has 20% VAT and it resolves the issue of clipping (tldr every panel will need an optimiser because I live on a tree lined avenue).

Is there a problem if an installer states they will deal with the DNO? I figured either the Squirrel pod is export limited which isn't an issue for me, or it is not limited and I have freedom in the summer months until I get an EV. Which would probably be in 2024 or so. Western Power are the DNO in my part of the Midlands.

If there were a battery system installed would there be any issue with a different installer setting up the solar PV?

Thanks everyone for your wisdom

Krill

Edit: used an insolar map to check average and peak yield. 16 panels would be the most I can fit on unless I literally cram 2 extra panels in the opposite orientation, and that is fitting the in landscape opposed to portrait. Newcastle under Lyme and I have a gas boiler and hob but use a multifuel burner in the lounge which heats the entire house and two kettles for hot water use during Autumn and Winter. Free wood self seasoned due to agreements and personal effort, coal as back up. Recently bought extra stockpot so could boil 25 litres on a stove for a bath...lots of plans to reduce gas use bit blindly forgot about electric use.

16 panels would meet total power needs for about 8 mo ths of the year, maybe 10: average between 240kW and 300kW per month looking at old bills but that includes previous winter when using gas boiler and a tumble dryer opposed to stove and clothes Airer. I have plans to reduce other power use but can't stop the peak use due to 3400kW electric oven.

[Oldgreybeard]

Regarding sizing the inverter I would look closely at the energy used not the peak power. The latter is a red herring in my view, as it doesn't really matter if the inverter can't deliver enough power for short duration, high peak power, loads. Our house is a good example, two ovens and and induction hob, that can easily peak at well over 6kW. Our inverter (a Sofar) can only deliver 3kW, but that doesn't matter in practice, just means we draw the extra from the grid for a very short time. The highest monthly peak rate usage we've seen so far is 3kWh, usually it's between 1kWh and 2kWh.

All that peak rate usage each month comes from the inverter not being able to meet the peak demand for very short periods, but it's actually cheaper to do this than have a bigger inverter that will almost always use more power under light load conditions. The annual cost of this peak rate grid energy usage is under £10, so even ignoring the additional standing loss from a bigger inverter it is unlikely that the higher capital cost would be recovered in the lifetime of the unit.

Well worth doing some reasonably fine scale energy use measurements if you can to try and get a feel for the way consumption peaks and for how long. I have Home Assistant running with a house power consumption display (it gets data from the inverter) and that gives a very useful plot of power used over a settable period, like this, which shows the short high power spikes and the underlying average power (ours is quite high as we have an air pump and a UV disinfection on 24/7). The square wave on the baseline is the fridge/freezer turning on and off via its thermostat, most of the spikes are the boiling water tap boiler turning on and off to keep its tank hot or our well water pump cycling when we use water:

House power consumption.jpg (29.63 KiB) Viewed 1365 times

Our induction hob can draw a lot of power when first turned on, but within about a minute or two the power starts to drop back to a level that the inverter can fully deliver. Same goes for the ovens, although the big oven takes a lot longer to get up to temperature. To get around that we've just bought a smaller multifunctional oven/grill/air fryer, and that both heats up a great deal faster and uses less energy, with a significantly lower peak power as well.

[Krill]

Thank you for the very swift response oldgreybeard. So quick that I was editting my first pst and you already beat me to posting!

I see the point about peak power use. Part of the equation is the up front cost, which is where I find myself in interesting times, like everyone else.

Simply put, I lack the knowledge and time to actually implement this system, so I am in the position that I need to use an installer, which limits the options to what they are willing and able to sell. So I'm going through quotes and stuck trying to be pragmatic.

My understanding, given the past week of trawling the internet for information is obviously extremely poor in the context of a forum and community such as this. I thought the Squirrel pod (Lux) inverters were actually small inverters but because there were 2 inverters in the quote I'm looking at, it could manage the greater charge/discharge rates? And the other side of the coin was that they would ensure that in winter there would be no clipping (looking at the average available power production in December and January, at times it would come very close to maximum charging rate for a single inverter, therefore it seems reasonable to assume that on good days there would be more available power but a single inverter would waste it. I think I may have missed this in the original post, my apologies for the mistake.

If the second inverter was essentially very low cost (given the different quotes I'm not comparing like for like), like a couple of hundred quid would this make it a better "deal"? I mean, if it was free it would appear to be a no brainer to me, and if that holds the line has to be drawn somewhere right?

Part of my thinking was that 1kWh was going to cost in excess of £1 come January and it will not go down significantly in the long run. When I mention that in person I see people goggle but on this forum I think I might be optimistic...

I take it you are happy with the Lux inverter? It's always good to read reassurance prior to a purchase

[Oldgreybeard]

Suppliers are always going to quote based on what they've been told, so if you've told a supplier you need 6kW to be available from the inverter(s) then that's what they will quote for. If you know how much electricity you use you can have a stab at making a rough estimate of the power you need. Say you use 6,000kWh per year, and that you think that 75% of that will be during the day (cooking, heating, cups of tea, etc). That gives you a daytime usage of about 4,500kWh, and if you take an average daytime period as being 12 hours then that works out to a power usage of about 1kW during that 12 hour period.

Charge time is a valid concern, as the maximum that the inverter I have will charge at is 3kW. If you intend to charge mostly from solar then at the time of year when you need the charge (winter mostly) then that 3kW is never going to be an issue with any PV system under around 6kW or so. Our 6kW PV system, which faces SSW, only gets close to actually delivering 6kW when the panels are cool and the sun is high in the sky on a clear day. Right now, for example, with cloudy skies, the system is generating 300W. For most of today it has barely gone above 1kW, and only then for short periods of time.

[Krill]

Charge time is a valid concern, as the maximum that the inverter I have will charge at is 3kW. If you intend to charge mostly from solar then at the time of year when you need the charge (winter mostly) then that 3kW is never going to be an issue with any PV system under around 6kW or so. Our 6kW PV system, which faces SSW, only gets close to actually delivering 6kW when the panels are cool and the sun is high in the sky on a clear day. Right now, for example, with cloudy skies, the system is generating 300W. For most of today it has barely gone above 1kW, and only then for short periods of time.

Thank you for the example, that's just what I need!

When you say "panels are cool and the sun is high", are you refering to spring/autumn time periods, or do you actually exceed the 3kW from October through February? I figure that there has to be a cross over point (or several, weather dependent etc) and if the second inverter costs, say £400 and generates 100kWh worth of power (used within the house, which otherwise would need to be bought off the grid) every winter that one otherwise would not be able to access, and that power is worth £100, then the inverter pays for itself in 4 years.

All the suppliers, FWIW are quoting for single inverter, multiple battery systems, but then there is a separate quote that has a double inverter system (The Lux Squirrel pod x2, 4 greenlink batteries for 12,8kWh claimed). When I break down the quotes the Lux Squirrel pod always comes out as the cheapest battery system even with VAT in a two stage install (battery first, then solar), unless installers decide they don't want to fit just a Solar PV system. Still getting quotes though. And in quote for the Squirrel pod the second inverter is £850. So I'm trying to figure out if the savings from the higher load and the potential better charging in winter makes it worth it; then there is the potential export benefit in summer.

I wish I understood the engineering better, I'm stuck using AS physics from 17 years ago...should have paid more attention.

[Oldgreybeard]

Our 6kW PV system usually generates around 6,000kWh in a year. Some years it maybe as low as 5,900, other years it may be as high as around 6,200kWh. Most we've ever generated in one day has been around 45kWh, and that would usually be around June to August, depending on the weather. Output around midsummer tends to drop because of the heat, heat really hits panel efficiency hard, and during the heatwave our 6kW system never got above 5kW, as the panels were just too hot to deliver more.

Today was a typical late summer cloudy day, no sunshine to speak of and our 6kW PV system generated the grand total of 9.5kWh, so an average power of under 800W. That's been split between consumption and charging the battery up a bit.

The numbers from PVGIS tend to be pretty close to reality, so are a good guide as to what you might expect to generate. The real energy is the key thing, as there is no real value in being able to either charge or discharge at high power if that is only something that occurs for short periods each day. In mathematical parlance, it's the area under the power versus time curve that matters, not the peak power, as it's the area under that curve that you pay for from grid imported energy.

[Krill]

I did not know about PVGIS, very interesting data. Thank you for pointing this out to me.

I'll have to peruse this data tonight for January and December, and figure out the integral as you say.