Hi All,
New to the forum, looking for some advice.
I have the following set up:
1 x AIO 13.5kWh AC coupled, 1 x Gateway, 7.8kWhp solar array (18 x 435w) connected to a Solis hybrid inverter S5-EH1P5K.
With the recent fine weather and the summer coming I would like to take advantage of the solar clipping I am experiencing and also add some additional storage capacity to my system as I have an ASHP.
Has anybody with a similar setup connected a DC coupled battery to a Solis hybrid inverter or similar and have it in operation with an AIO?
Thanks.
The problem you will have is that the two inverters (AIO and Solis) will have no knowledge of each other so when they detect house load they will both try to discharge to meet the house load, then they will sense the excess export and try to charge, and you basically end up in a race condition where the inverters will cross charge each other - quite probably repeatedly and at high power levels.
There are ways round this, using home assistant to detect the inverters cross charging and to stop the activity, or to control when the inverters charge and discharge, but they take time to setup and have some compromises.
You might be better to expand your AIO with further storage which would mean no cross charging, but wouldn’t address the clipping issue.
I’d also suggest you look at the economics of it all, whether capturing the clipped solar or expanding your battery storage to reduce winter grid import for your ASHP is actually going to have anything like a sensible payback. I have two Gen 1 hybrid inverters each with their own batteries, they too cross charge in the evenings but nothing like as aggressively as a more modern inverter would. I have an ASHP as well and have looked at getting more storage but calculate the payback is between 10 and 22 years !
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Hi Geoffrey,
Thanks for your reply, I had a feeling that was the response I was going to get in regards to cross talk, I have read a lot about this problem with such a set up. Just hoping someone on here might have had a working solution.
I have a few ideas I am currently exploring to try offset the ASHP power consumption in winter, additional battery storage and cheap night rate tarrif being one of them.
I also have a river which runs through my property , so I am investigating the potentail power output which could be gained from this with a hydro generator and trying to figure out how to combine / configure this to work with my current set up.
Thanks again for you input.
To be honest being on the right tariff is probably going to be more important than adding extra generation or battery storage.
I’ve had my heat pump for 3 years and batteries and solar for 2. First year of the heat pump I was on a fixed rate and then SVR, and yes it was expensive.
After getting the batteries I looked at how to optimise their use, ending up with Home Assistant with firstly my own scripts and then Predbat to manage the battery activity. After lots of spreadsheet calcs I moved to Octopus Agile for the next winter on the basis that whilst it may not be as cheap as an EV tariff for overnight charging, since the ASHP consumption dwarfed the battery storage, the average overall rate I was paying was more important.
I was on Agile for 14 months and it proved to be a good choice. I only moved off Agile in January this year after a prolonged period of high Agile prices; when I moved to Octopus Cosy.
If Agile comes down in price again I may well move back, but it does need decent battery automation. Otherwise Cosy is quite a good choice, the 3 charge periods a day and use of a battery means most of the heat pump and house load is on the cheaper electricity.
Unfortunately I don’t have the option for dynamic electricity tariffs such as Octopus Agile or cosy.
I live in Ireland and such tarrifs are not available, currently I have to make do with EV tariff cheap night rate (2am -5am) for battery charging and ASHP.
In winter (poor solar days) AIO doesn’t have enough capacity to meet demand of house load and ASHP for full day, hence the reason for exploring the additional DC battery.
Compatibale DC batteries with Solis inverter are much cheaper option than an additional AIO.
If this was achievable via automation in Home Assisatant I would consider this, but as you mention in previous post the economics and payback would have to make sense.
Ah thanks for the extra info @Keith83
Agree, GivEnergy batteries are still comparatively expensive.
If you go down the Home Assistant route there’s lots of control options with automations you could adopt.
One automation could be to charge both sets of batteries overnight, then put say the Solis battery into pause discharge mode so it doesn’t discharge, let the AIO handle the load and when the AIO SoC drops below a certain SoC % you put the AIO into pause charge mode and unpause the Solis battery.
This means you only ever have one inverter trying to supply house load at a time.
Another approach is again charge overnight, then put the AIO into Eco mode and set the Solis into discharge mode, discharging at the rate of your average background load during the day.
Since the Solis is discharging then it can’t try to charge from the AIO. If your house load drops below the Solis discharge rate then the AIO will cross charge from it, but since the Solis discharge rate is limited, it won’t be a runaway cross charge.