The Sunny Island + Sunny Boy system is very good.
With 1x 6kW SI you can connect 2x 6kW SB, and with over-paneling and multiple orientations, produce close to 12kW approaching 10 hours/day. 6kW to loads, 6kW to batteries. At night, draw 6kW from batteries.
SI can surge to 11.5kW for 3 seconds, enough to start 2kW or so induction motor.
I have 4x SI wired for 120/240V and some Sunny Boys. 20kWh AGM. meant for backup, not daily cycling. (got the SI for $0.25 on the dollar)
The TriPower Smart Energy is interesting, but uses expensive HV battery (don't know what BMS for DIY), and is an HF design with (I think) very limited surge capability. The specs I see for somewhat similar US models only surge to about 120% of continuous rating.
It includes transfer switch, good for grid-backup. I'm planning to install their US model Sunny Boy Smart Energy for my sister, and that model requires external transfer switch (and auto-transformer for split phase), bringing the cost to $5000 or so.
For the price you may get better performance from Victron.
If you spring the 3x or so cost for a Sunny island system, that should perform very well.
It does sound like you got your Sunny for a good price
For me the hi-spec power is not an issue, I produce like 8 months a year more than I can use with the little I have already. So my main goal is to improve user experience and utilization. Particularly utilization of Heat Pump, which is used year-round for heating water. With the SunStone 5 KW AIO inverter I believe it sometimes kicked out power or switched to grid (different replacement units behaved differently, having different faults
bellow 4 kW of real power. That was issue with my heat pump, even though it's a small 9 kW output (it uses like 4+ times less power from spring to autumn, so definitely under 3 kW at full blast) pump with inverter "soft" start without surges. It may use over 3 kW during start up though, and with other appliances on (i.e. fridge kicks in, etc), it caused some troubles, so I didn't use it.
The surge is of course true with power tools and such, as you describe it.
Someone claimed in Victron forum, that Multi RS solar can take also up to 11 kW surges, but I think it was a mistake and the author confused EasySolar and Multi RS units.
And that brings me to my unresolved point, that I started to think again about (before you even wrote the post
): What's better - 4 kW with large surge capacity (i.e. EasySolar II) or 5 kW with a small surge capacity?
Elaborating on that using ChatGPT:
- For the Victron MultiPlus-II 48/6000, the surge capacity is typically around
15,000 watts (15 kW) for a few seconds. This surge capacity allows the inverter to handle appliances and equipment that require a higher starting current than their normal operating power.
- The Victron Multi RS 48/6000 is a specific model within Victron's range of inverter/chargers. For this particular model, the surge capacity of the output power is typically around
12,000 watts (12 kW) for a few seconds.
Both sounds fantastic, but I don't know if true. ChatGPT is not always getting correct results and Victron forum is full of contradicting opinions. The Multi RS manual states:
High peak power - The inverter is able to supply a maximum AC output power to a peak 9000W or 50A AC, for 3 seconds. Thissupports smooth operation for motor start up and other demanding surge loads.Continuous power output, with solar boost - Continuous output power at 25C t ambient, at 52VDC, is 5300W. When combinedwith solar power from the built-in MPPT this increases approximately 10% to 5800W.
...which is very good as well! Totally fine for power tools and I hope also for the heat pump.
One consideration I found is, that Multi RS is a new product and is only kind of developing within Victron's portfolio and there is much less experience and community support.
I should also say, that the switch between grid and solar system for the heat pump is now manual, but I plan to replace it with a smart switch and employ some kind of rules management when the pump is allowed to use solar system (based on season, time, battery SOC or even cloud overcast forecast) and also set water tank preheating for certain times, etc.
