Could you give me some advice on how you’d split up the modules? I’d like to use Jollywood JW-HD108N-R2 500W modules. I can fit 16 on the south side of the house roof. There’s room for 6 modules on the north side. I can put 12 modules on a (slightly larger) garden shed, but they’d be flat. The roof runs east to west, with a maximum slope of 15 to 20 cm over 4 metres. There’s no shading to the south. Now I’m trying to work out how to split up the modules. The shed is about 26 metres from the house. For that reason, I thought it might be better to put a Fronius in the garage (right next to the garden shed) rather than run 26 metres of DC cable. I’d like to use 3 MP2 6K5s and a 15 kWh battery. I was thinking of putting the 16 south-facing modules on a Fronius and the 6 on the north side on an MPPT RS 450/100.
What do you think of this setup, and especially, how would you do it? Is this optimal, or would another arrangement be better? Or would it be better to run a long 26-metre DC cable down to the basement after all?
With the 450/100, I’d try connecting the 6 north-facing modules in one string and another 6 from the south-facing roof to the other. You’ll need to check what the voltage limits allow. Connecting the 6 north-facing modules as 3 and 3 to the 450/100 would be a waste of the RS. Better to go with 3s2p on a 250/60 or similar.
And use a Symo for the rest again.
Your battery is more than a little undersized for 3 × 6.5k. Have a read here about the 1:0 rule for battery storage, too.
Your panels are listed in the Victron MPPT calculator.
You can connect 6–10 panels in series per MPPT on an RS450. In terms of current, 6–8 panels would be ideal.
6 per tracker if all trackers are used at the same time.
7/8 per tracker for an east-west installation.
Consider getting 3x Multi RS 6000 units. Similar output, no humming, and the trackers are already integrated.
Otherwise, I’d power the 22 panels on the house with an RS450/200.
For the detached garage, I’d use a Fronius if there’s no shade, and microinverters such as Hoymiles HMS/HMT if there’s a lot of shade. With the latest OpenDTU, they can apparently also be throttled while connected to the grid, if necessary. If the grid goes down, all the PV inverters operate using frequency control.
No, I don’t need that many modules at the moment. But at some point I’d like to get an electric car as well. A heating element for the water in summer would be nice too. I already have a storage tank here, but there’s no way to fit a heating element in it — we’ll see. Maybe I’ll get a split air conditioner too, after this extremely hot summer.
Looking at the costs, I’ll have the whole roof covered, because the cost of the modules and everything else is just ridiculous. Scaffolding: €1,100, lift: €600, call-out charge: €300. At those prices, I’ll fill the whole roof — you never know. And having some extra modules installed later wouldn’t pay off at all. Better to have more than you need than to need more later and not have it.
Thanks for the detailed reply. I thought I needed an additional Fronius for this. If it works with the RS450/200, that’s great. I thought the grid operator only counted the panels’ capacity in kWp, and not the inverter output, towards the 25 kW limit. Does anyone here know how Westnetz calculates this? I definitely don’t want to exceed 25 kW.
By the way, is the humming really that bad? The units will be installed in the basement, so surely you won’t be able to hear them on the ground floor?
The PV system’s kWp rating is used to calculate the feed-in tariff under the EEG.
The requirement for a ripple control receiver, on the other hand, depends on the 25 kW limit for the inverters (PV and storage) and is interpreted differently by each grid operator.
AC-coupled PV, e.g. Fronius, may be counted together with the storage inverter in the total.
I also have an electric car… and my solar array is about 5.5 kWp, and I have an MP Ii-3000
With that, I cover over 90% of my consumption in summer and around 60% over the whole year…
So you really should run the numbers when it comes to the costs… especially since the payment for exporting electricity is quite low… and soon probably “nothing at all”…
I’m also in favour of this solution. Put a dual microinverter, such as an APS DS3-H rated for up to 960 W, on each pair of panels. That’s how I have mine set up, with panels facing SE, S and SW, and it lets me make better use of the electricity generated at home, with a flatter generation curve. The wiring is also much simpler: you convert directly at the panel to 230 VAC, and if one panel breaks, it doesn’t affect the others.