Adding to existing system

[DavB275]

Currently have an off grid system with 3.5kW PV, feeding via Sunnyboy into a Victron inverter/charger to a Pylontech battery bank. This qualified for the original FIT payments, so I don't want to mess with this.

I now have an additional 2.1kW of new panels available. To make use of these, is it as relatively simple as connecting via an appropriate charge controller, into the battery bank as well, or do I need to be aware of anything else?

[nowty]

Currently have an off grid system with 3.5kW PV, feeding via Sunnyboy into a Victron inverter/charger to a Pylontech battery bank. This qualified for the original FIT payments, so I don't want to mess with this.

I now have an additional 2.1kW of new panels available. To make use of these, is it as relatively simple as connecting via an appropriate charge controller, into the battery bank as well, or do I need to be aware of anything else?

It works and is FIT friendly, I used to have almost the same offgrid setup but the Sunnyboy fed a Sunny Island inverter/charger.

As its offgrid, the battery bank will fill up faster with the extra power from the charge controller and then as you know your Sunnyboy will throttle back, so your FIT yield is likely to reduce unless you have some sort of use for the extra power or have a dump load. I managed to get a diverter working on my offgrid system so it dumped power to a 3kW heater.

Alternatively, instead of charge controllers, you could add a second Sunnyboy and feed it to the Victron inverter/charger, tapping in downstream of the FIT generation meter.

[sharpener]

If you have a Victron inverter then you can configure it not to export any surplus from a charge controller to avoid throttling the Sunny Boy. I do that to reduce the fan noise as I am still waiting for the retrofit kit which should reduce it.

What I don't understand though is how you are getting FIT payments for what you describe as an off-grid system.

[nowty]

What I don't understand though is how you are getting FIT payments for what you describe as an off-grid system.

Offgrid systems were eligible for FIT.

Some people incorrectly think "Feed In" means into the Grid, but it actually means "Feed In" of new technology via a subsidy.

Latest FIT Guidance Doc,
https://www.ofgem.gov.uk/sites/default/ ... 282%29.pdf

Page 26,

Off Grid Sites

4.17. Off grid sites are required to meet the same eligibility criteria as grid connected sites
(discussed above). In addition, off grid generators will be required to sign the following
declaration:

"I hereby declare that it is my intention to use any and all electricity generated by my FIT
installation and that I fully understand that any electricity generated but not so used will not be
eligible for FIT payments."

[DavB275]

Thanks @nowty - helpful as ever!

Correct about the off grid FIT. We were fortunate enough to get the first (highest) rate, which has been enough to cover the costs of diesel in our backup generator.

[sharpener]

Thanks @nowty - helpful as ever!

Correct about the off grid FIT. We were fortunate enough to get the first (highest) rate, which has been enough to cover the costs of diesel in our backup generator.

My misunderstanding. So you won't be using ESS which is for grid-connected systems. Can you do something with Assistants or failing that NodeRed?

[DavB275]

My misunderstanding. So you won't be using ESS which is for grid-connected systems. Can you do something with Assistants or failing that NodeRed?

Sorry sharpener, but I don't know those terms. Really just looking for the simplest way to make use of additional panels without affecting anything else.

[sharpener]

My misunderstanding. So you won't be using ESS which is for grid-connected systems. Can you do something with Assistants or failing that NodeRed?

Sorry sharpener, but I don't know those terms. Really just looking for the simplest way to make use of additional panels without affecting anything else.

Sorry, as you said you had a Victron inverter/charger and it is not mentioned in yr sig I assumed it was something like mine (see under).

Assistants are add-in software which gives extra features. Energy Storage System in particular is the one for optimising a grid-connected storage system. There are others for other situations.

NodeRed is an optional scripting software package in which you can write your own algorithms, I use it for reducing fan noise at night.

If you post details of your installation and what you want to do here https://community.victronenergy.com/spa ... fault.html you will tap into a wealth of further expertise.