Using Hybrid inverter without batteries.

[CGelectrical]

Hi guy's. I need some inputs here please. I have a client that wants the following. Inverter and panels only. During day time it should use pv array if insufficient then it should turn automatically to eskom. At night and morning times it should switch automatically between eskom and pv array. Then the tricky part. When loadshedding occurs during daytime it should use pv power if sufficient not switch off the system. Is that possible. I heard you can do it with a sunsynk inverter not sure how true this is.

Thanks
Conrad

[Justloadit]

You never mentioned what size inverter, and how many panels, and what loads.

Probably will work when there is ESKOM and sun, but will be erratic with solar panels only, and switch the loads on and off during Load Shedding and running on PV, because it will not have sufficient energy to drive the load.
Every time the load reconnects it waits a few seconds, then switch on again, and if the inrush current is too high, it then again shuts down.
Just remember PV panels are current sources, not voltage sources, so any quick demand will cause the PV Voltage to collapse while the PV current remains constant, and there will be insufficient energy to maintain the load connected.

I would NOT recommend using the inverter in this way, and may probably cause premature failure.
Any quick change in the load, and the inverter has nothing to fall back on to supplement the demand.
Even a cloud coming over the PV panels will cause a similar issue.
Thats where the battery comes in, for that short period of time it is a power source.

If a 5.5kW inverter, minimum of a 5.5kW lithium battery, best 11kW, even better 15kW. minimum PV 2.6kW best 5.2kW
Take my advice don't offer Lead Acid, even if cheaper, you will regret supplying it.
If an 8kW then minimum 11kW better at 16.5kW, minimum PV 5.2kW best 10.4kW.

Trying to supply a cheap solution will disappoint everyone and create an illusion that solar is crap.
Doing it right will ensure a good quality energy system with pleasant experiences from the client.

[Dylboy]

Agreed with the above 100%

A punt for sunsynk, i have recently done a Sunsynk 8kw and it has blown me away.

When there is excess PV and batteies charged it then feeds to the non essential items. That is what sets it apart to the "cheapie" ones as well as it is AC coupled for those larger loads moments.


If your client is trying the phased approach, then perhaps recommend a Gel battery and in lieu of changing to lithium. Just to try combat the loads on and off due to PV as stated above and the Gel battries cheaper.

However the extra labour and all that when it comes to changing may not make it worth while for them.

Sent from my SM-N960F using Tapatalk

[Justloadit]

Rather start with the 2.4kW lithium, probably same price as 4 off 100Amp Lead acid, but you will get 4 times the life out of it.
Lead acid do not like to be cycled that often as will be the case in the hybrid arena.
Also they take to long to charge. Typical charge time for a Lead acid is between 4 and 12 hours depending on the discharge, where as Lithium will charge between 20 minutes and 2 hours if completely flat.
Another advantage with lithium, is that small frequent burst of charge, do charge the battery where as Lead acid does not bode well, as it wants long times of constant voltage.
Think of your cell phone, when you plug it in for 20 minutes to get an extra bar or two, where lead acid you can not do that.

My experience, lead acid after 200 cycles loose capacity quickly there after, lithium 2 to 4000 cycles. You cannot even compare.

[Alfred M]

I agree fully on your statement but most clients don't want to pay the money for lithium Ion most of my clients go for gel
Hubble AM-4 25.5V 2.6kWh Li ionBattery 16.5k lots of $$$

[Alfred M]

Hybrid inverter uses solar array and grid power input in the event of grid failure inverter will switch off sensing both inputs solar and grid power so in the event of load shedding you will have no power output you need battery and ups setup when losing grid power

[GCE]

Hi guy's. I need some inputs here please. I have a client that wants the following. Inverter and panels only. During day time it should use pv array if insufficient then it should turn automatically to eskom. At night and morning times it should switch automatically between eskom and pv array. Then the tricky part. When loadshedding occurs during daytime it should use pv power if sufficient not switch off the system. Is that possible. I heard you can do it with a sunsynk inverter not sure how true this is.

Thanks
Conrad

I agree with the previous statements above

All you can do is use it as a standard grid tie inverter - without it seeing grid it will turn off .
You cannot use the essential output part of the inverter without potential damage.

I am assuming that the owner wants to spend money in stages and essentially wants to benefit by saving some daytime usage through PV and effectively start to enjoy the return on investment.
At a later stage add the batteries and take the headache out of load shedding.

Alternatively if the load shedding is his biggest grip then leave panels out for now and spend the money on batteries - You could then have the back up feature complete all wiring to suit and at a later stage add PV to save electricity.

If the intention is to not go with batteries at a later stage buy a str gridtie inverter which will work out cheaper than a hybrid inverter.

At the office we have a hybrid and had lead acid batteries along with PV connected. With continued outages in the area I bought a Tesla powerwall which has it's own built in bi directional inverter and now use the hybrid as a grid tie only.
When my hybrid, which is already on borrowed time, packs up I will then buy a str grid tie to replace it.

Everyone has different objectives and priorities and until they let you know what they are it is difficult to give sound advice.

[Dave A]

Rather start with the 2.4kW lithium, probably same price as 4 off 100Amp Lead acid, but you will get 4 times the life out of it.

That point should probably come with some warnings.
Just watch out for current limitations when going that small on the lithium batteries. Most 48V 2.4kWh packs I have seen are spec'd to 50 amp maximum steady draw per pack. A 5kW inverter will need at least two in parallel and even then one assumes you are not living on the limit.
Probably as well to point out you also can't just "save up and add another battery later". They really need to be treated as sets to get the maximum performance and lifespan out of them. And for the money invested, that is what you want.

Alternatively if the load shedding is his biggest grip then leave panels out for now and spend the money on batteries - You could then have the back up feature complete all wiring to suit and at a later stage add PV to save electricity.

Absolutely spot-on.

[Alfred M]

Hi Dave just a question off the topic.How do i reply on a questions inserted like you have done above sorry i am still new to the forum and still finding my way around the page setup

[Dave A]

Hi Dave just a question off the topic.How do i reply on a questions inserted like you have done above sorry i am still new to the forum and still finding my way around the page setup

Click on "Reply With Quote"