DIYrich
Solar Wizard
No, but it may have a bearing on the solution. Micros may push it over 3.6kw, so charge controller may be better.
Mismatched strings - south/west facing roof.
- Thread starter mattg4321
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wattmatters
Solar Wizard
This is the issue they are trying to solve:
Setting an inverter's export limiter (if required) is trivial. It will account for any extra generation from any additional small inverter.
Since the OP does not have a battery and that is some way off, it doesn't help them get the extra 885 W of south facing PV capacity.
MisterB1959
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The Sunsynk works exactly the same. I have a 3.6 Aurora Power One inverter installed under FIT and a Sunsynk ECCO 5kw. I use the microgenerator setting on the Sunsynk to harvest any excess from the FIT PV system.
However, when I fit my second battery, I may just sell any PV production back to my supplier as I can buy and store electricity at half the price I can sell back at. The additional battery will give me enough capacity to supply my needs 24/7. At the moment I get a deemed export of 50% of what I produce at a third of the price I could get if I sold my actual export or even better ALL the power I produce. From the calculations I have done, I could 'earn' an additional £450 per year!
The UK-approved Solis Hybrid inverters (like S5-EH1P) will charge batteries from a secondary microgenerator (in my case, a second Solis). So, if the PV only inverter (whatever make) is producing more power than the house load, then the surplus will be used by the hybrid Solis to charge its batteries, simultaneously with it's own PV production. Not sure if this is common to most hybrids or whether the Sunsynk supports that mode of operation, but it works with the Solis.
We had a separate thread on that a month or two ago. I'd be wary of just connecting two inverters, particularly two different makes, to the same battery connection unless you know that the battery connection is truly floating. My Solis hybrids have a voltage of nearly -200V with respect to ground on their battery negative lead!
Even it it were possible, there would be issues, IMHO, with battery to inverter comms. Without a MITM controller the battery would instruct both inverters to charge or discharge at a given current, which would then effectively be doubled if you have two inverters trying to achieve that charge or discharge rate. Far simpler to use AC coupling.
In your situation, I'd prefer to use a small string inverter, like the small Solis you mentioned, for your 3 panel array, rather than micro-inverters.
Thanks, my feeling is that this is the way to go, best bang for buck and quickest payback, which is what I’m looking for really. As per the later post it seems this is also possible with the Sunsynk that I’ve already specified in G99 DNO application (although I’m sure I could change to equivalent solis if necessary).
Thanks everyone for all the suggestions, really appreciated.
This is great to know. I’ll have a read up on how to use this setting on the Sunsynk so I can take the power production from the 0.7kW solis and charge the battery with it when fitted.
I must admit that I really don’t like the idea of connecting multiple chargers to a battery.
MisterB1959
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It's quite difficult to find the information on how to set it up, I will try to find the relevant you tube video where the found it. Or you could ask Sunsynk prior to selecting it OR I could copy you my settings ?
As long as one charger takes control over the others then not an issue.
It is quite difficult to find.
It seems like I would connect ‘Grid’ terminal from Solis 0.7kW inverter to ‘Aux’ terminal on the Sunsynk. Then set it up in auxiliary load settings on Sunsynk menu to ‘for micro inverter input’. There are some other options relating to this on page 68 of the manual linked below that I’ve not fully worked out yet.
MisterB1959
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It works really well to be honest and doesn't require additional wiring etc, it just uses the cable that supplies the inverter as bi directional and settings on the inverter. It effectively allows you to have three separate strings. The main issue I don't like is that there is no accurate reading provided in real time to tell you what us going into the battery, though it's not difficult work out, but I don't think you should have to !
Can I ask what your trying to achieve long term? It seems to me that spending money on a battery and inverter might make more financial sense than solar and an inverter? If you have an EV then even better to concentrate on the inverter and battery ..
Can I ask what your trying to achieve long term? It seems to me that spending money on a battery and inverter might make more financial sense than solar and an inverter? If you have an EV then even better to concentrate on the inverter and battery ..
I don’t have an EV currently. Main reason for doing it this way around is doing an extension, with roof replacement, so it’ll be easy enough to get some panels on the roof whilst all the scaffolding is erected.
Depending on how things go with the extension (unforeseen extras cost related to groundworks being an obvious risk), I may be able to fit a battery at the same time. Ultimately the aim is a reduction in bills. Plan is to be here long term so hopefully it’ll be worth it.
Depending on how things go with the extension (unforeseen extras cost related to groundworks being an obvious risk), I may be able to fit a battery at the same time. Ultimately the aim is a reduction in bills. Plan is to be here long term so hopefully it’ll be worth it.
KevinC_63559
New Member
WOuld not (2) MPPT charge controllers be your best solution? I've always heard you wanted separate controllers when having panels groups that are aligned differently. Its my understanding that having multiple MPPT controllers going to a common battery group is not an issue - each will sense the battery voltage and charge as needed.
wattmatters
Solar Wizard
OP is not getting a battery, at least not yet.
So the string voltages still need to be within spec for the MPPTs. OP has one string in the 80-90 V range, the other is 300+ V.
Not many grid tied PV inverters with 2 (or more) MPPT inputs can cover both regular higher voltage strings and very low voltage strings.
