I recently tidied up the system at home to make it a bit more presentable.
- Multiplus-II 5000 - set to G98 grid code
- 3.2kWp panels in 4S2P configuration
- MPPT 250/70
- 6 Pylontech US5000 batteries
The system is outside the property in a small shed and in a grid parallel arrangement.
The batteries are housed in a steel tool cabinet (kind of thing used on a building site for secure tool storage). Insulation and a heater will be installed in time for the winter but we thankfully don’t get many days of extremely cold weather.
There is makeshift roof for the battery cabinet which isn’t pictured. This keeps the rain and direct sun off the cabinet.
This was a self-install system hence there is a few hoops to jump through to get paid for exporting to the grid in the UK. I’ve not bothered with this and opted to focus on self-consumption.
In order to make use of excess solar PV I’ve setup a hot water heater as a dump load. This is controlled by NodeRed using a Shelly relay, contactor and some temperature probes in various places for monitoring.
Rather than a typical immersion element fitted directly to the hot water tank I opted to use a “Willis” heater. Without going into great detail - this takes advantage of a thermosyphon to heat the tank from the top down.
The plumbing of the hot water system is a bit of a mess so I’ve not pictured the whole thing.
Example of some flows which control the dumping of excess energy to hot water
A fairly simple dashboard that tells me what I need to know.
