I’m keen to have a Victron setup. I’m a keen user of home assistant, and I’ve been drawn towards the Victron products due to their wide support for integrations and open communication standards, and finally because I don’t have to use their cloud if I don’t want or need to.
But there is possibility that there isn’t a Victron solution for me.
I have a UK home, main consumer unit at the front side of the house where there is uncontested space (2M wide).
at the back of the garden is a new well insulated outbuilding, which has the most appropriate roof space for solar (16 panels).
My priority is battery storage and then solar. I need 24KWh of storage, i’m looking at Fogstar 2x 16KWh modular batteries, which are a reasonable size at w850, d450, h250mm.
there is a 50M of 10mm SWA running from the main consumer unit directly to the outbuilding, this was spec’d to be in excess of my requirements for hobbyist workshop equipment in that outbuilding. There is also a 3 inch conduit from the outbuilding to the back of the house, this can enable direct comms as there already exists Ethernet cabling to the front of the house as well (to the consumer unit).
The options I’ve been thinking of:
DC Coupled: both battery and solar and big inverter (8000) go in the outbuilding. energy monitor at the main consumer unit with a direct connection (Ethernet cable).
upsides: efficiency of solar charging. less equipment cost. less conversions
downsides, I can’t use the EPS out on the Victron inverter other than for the outbuilding. I can’t use the same 10mm SWA to power the house if there is a power cut, I would be islanded. no transfer switch at the main consumer. possible voltage drop on the 10mm SWA.
AC Coupled: the batteries and big inverter (8000) go down the side of the house in a electrical kiosk for protection. The solar and a smaller inverter go in the out-building. Solar generated has to be converted 3x before it is useful DC (solar) → AC (trans) → DC (stored) → AC (used).
upsides: more space for the batteries at the side of the house. doing the batteries first will be easier. Less reliance on the 10mm SWA. Powercuts+ (not that we have many at all). Installing the battery, I don’t have to move 125kg to back of garden, twice.
downsides: increased equipment cost, extra inverter, extra cerbo, and do I really need another battery in the outbuilding? - what kind of battery?
other thoughts, I would want to add more solar sites in the future, I can get a few panels on my main house for example. so understanding how my solution scales is important because i’m going to be faced with it sooner or later.
I’m absolutely interested in what others would do. I think i’m right to focus on battery first.
Does Victron have a AC coupled solar generation solution? or does every Victron solution require a battery, if so what is a minimal solution?
Hi mate as far as I’m aware Victron is an off grid system so batteries needed to run the system. Either way is going to cost you, I would be inclined to take the mains to the out building via 5 core cable.
Why? one sounds like the work shop is big 16 panels so more room for expansion and a big CU, it will satisfy part of PAS batteries not in habitable space.
You say about efficiency this only comes into play if you don’t use it, if the AC is being used then it’s only converted once. If you take a step in the future are you going to get heat pump or EV charger in which case the AC solar will aid the Victron as it wouldn’t have to supply the full load.
Is the Grid paying for surplus back to it depends how much then just let the AC flow back. Once they stop paying enough then the two technologies mentioned are very good at eating up that power.
I’ve gone for AC as it gives me more power ie 10kVA Victron with my solar in summer I can run a potential output of 14kW, which is very handy if they start getting silly with exporting then could get AC heating and cooling and just self consume so I can adapt to possible future changes re-export or self consumption.
The other reason is if the Victron system goes down I’ll still have AC solar so the bill wouldn’t be as much as losing everything and the same applies to losing the solar, as no system is reliant on the other to operate. But that’s my thought process, hope it helps take a look at some of the systems and go from there.
I would use AC PV and size it for the main base load, very efficient. But using that for battery charging is not.
DC MPPT for battery charging.
For a building a system up to where it needs to be if backup is a priority, saturate the DC side first then add AC coupling to specific loads.
If you have a decent IT nework you can even distribute installation and production direct to loads at their location if the DVs are distributed as well.
Other approach is set up AC PV and as you save money on power bills pour it into the batteries and rest of the system.
Good point about the solar being used is only converted once and yes Future EV is possible, heat pump requires more thought (victorian house). I’m not hopeful for export.
If i’m not mistaken, routing the mains to outbuilding at end of the garden into the inverter and back out to the main CU will effectively be 100+M of 100A capable copper which is going to require a gauge that will be impractical to work with?
So I read your message as more inline with the 2nd of my two options? is that right?
Hi mate yes route two, theoretically yes 100M but I would get a spark to do the calculation for sizing mine was only 25m so 25mm 5core armoured. But having batteries exposed to the cold or heat is always going to be an issue to heat or cool, mine are in my garage and I have automated heating and cooling as it can swing still in shelter. If you look at the warranty on some of these batteries most will stipulate cycle life at 25c so you kind of want to be as close to that as possible.
Yeah for me it would be air to air not a wet system as the conversion of heat to water and then rely on convection with something with limited fins doesn’t strike me as the best but I’ve just had a new boiler which can modulate down to 3.2kW so they should have systems that are a lot better priced in 15 or so years and don’t say it boilers are wet systems but instant heat to in effect water but higher temp so convection is much better lol
@lxonline good point but depending on what side of the inverter it’s going but yes a point that I missed, 16panels ruffly 7.8kW for 490w panels.
I would make sure if you go for a multi get the biggest one so you can throw the whole house on back up, people said you don’t get many power cuts that is true but if and when it happens just sit back and bask.
I had all the street lights and 320 house go dark, PS turn your outside lights off as people are drawn to it like moths lol.
Yep correct and that only applies to if you put it on AC 1 out so 10 kVA say 10kW PV max but you can also in addition to that put 20kW on the AC Input with a meter so it knows it has AC solar also coming through the AC input. As far as I’m aware @lxonline will put me straight if not.
The rule is more for island mode basically PV can’t be bigger than the inverter on AC 1 out as in a grid down situation the inverter has to be able to dissipate the energy.
The 1:1 rule applies to AC pv on the inverter output. Even if you don’t ever expect a grid outage. (Sometimes there is grid rejection)
You can go less.
You can put what ever you want before the inverter.