Probably a simple question ... I have a system with solar pv, Hybrid Inverter & batteries
A friend is having a similar system installed but is quoted with an AC inverter. Could someone advise the basic differences please? Sorry if it should be obvious but I tried to understand from datasheet...
the ac inverter just controls the batteries (charge and discharge) there is a separate inverter for the solar panels if fitted.
the hybrid inverters connect to solar panels and battery.
Or so i think.....
This is my understanding.
The hybrid inverter is an all in one solution; inverter for the panels, charge and discharge for the batteries and controlling the switching between the grid, solar output, and batteries to feed the house needs.
So it is a good solution providing the inverter power handling capacity is enough for the maximum output of the solar panels.
In my case the maximum panels output can exceed the capacity of the hybrid so a separate inverter was used to purely handle the conversion of the panels to AC. The AC inverter then still provides all the functions of the hybrid inverter but because it is working primarily with AC to switch between grid, external inverter and house it is less limited in its overall capacity. The inverter part of the AC inverter is used just to handle the battery and convert its output to AC. The capacity here will just limit the maximum flow to and from the battery not the overall capacity of the system.
Tim Adams Hybrids will handle PV to battery or home, and battery to/from the home whereas AC-coupled can only handle battery to/from home. AC-coupled are often installed where there is existing (especially FIT) PV, or where PV isn't really an option, or where PV is maxed out and there is further demand for timeshifting load by using battery.
Since we had FIT panels we had no choice and had to get AC coupled. When I get my new install done it'll be 1 or 2 hybrids instead, be it Giv or Libbi.
Every time you convert from DC to AC or back again you lose some energy so since all the batteries are DC, being able to just directly feed them DC is more efficient. The power is only converted to AC for your home when it is actually needed.
it is possible to replace your current FIT inverter with a hybrid inverter and upscale the number of panels too you just need to inform your FIT company that this is being done and they'll pay prorata i.e. original 1kw FIT system + 2.6kw more you'd get paid 51p for the the first kw then the SEG for the extra 2.6
A major advantage of the AC inverter is being able to monitor the battery drain or supply. this enables you to integrate with a zappi or eddi device easily.
thanks for all responses - very helpful!
Also, if you have separate PV and AC invertors you get a measure of redundancy. If PV or battery stop working for any reason it doesn't knock out the other supply.
Crucially for me though, If you hve two inverters you can draw their combined power in times of heavy load. So when, for example, our electric shower is running, BOTH the battery and the Solar PV can contribute to that load. We thus can get up to 3 + 2.5 =5.5 kw from the solar and battery systems. Which helps with the 9kw shower load.
PatrickMills inform your FIT company that this is being done and they'll pay prorata
Doesn't affect us but that sounds amazing. Everything I'd heard to date was that people couldn't change their original install because it would stymie their FIT payments.
PatrickMills This is news to me. I know that the RHI scheme has systems in place to allow you to change the pump should it fail but that with the FIT system even replacing a faulty panel could be a pain as you needed to replace it like for like. On that basis you'd understand people not wanting to try and fiddle with inverters especially given the income generated if you just leave it alone.
You can of course just add more panels that are not connected to the FIT array/inverters/meters and while you'll have to tell the DNO so that they can not let you export it at all or pay you a pittance, you don't have to do anything with the FIT.
positor1 I think this is where an umbrella solution makes sense so that your charger and diverter are all getting smart data from within the same ecosystem, up until now nobody I think makes all 3 though that is about to change with Myenergi joining the battery side and Givenergy one day actually releasing their diverter and chargers.