Going off grid

[openspaceman]

8 hours ago, Stere said:

Some  CHP info

 

https://www.pace-energy.eu/wp-content/uploads/2020/06/PACE-T1.4-Training-Documents-Module-1-Basics-FV.pdf

I skimmed through that but it mostly seemed to be a sales pitch for fuel cells, agg221 gave reasons why these are both delicate and a bit far from mainstream still.

 

If I were to be forced off grid I'd plump for a mains changeover switch and running an LPG converted Honda EU200i for a few hours a day IF I could figure how to prevent the demand from the house overloading it when the  6kWh battery pack couldn't take up the slack. Shame there doesn't seem to be a water cooled option. The idea being that as my system depends on the grid for the PV to charge the battery I have to have a good sine wave present mimicking a grid presence at the consumer unit to keep it all working.

 

 

[openspaceman]

On 08/01/2022 at 10:58, Dean Lofthouse said:

On average we are using 7kw hours per day. You can reduce usage from your battery by boxing clever. Only do heavy usage stuff while you genny is running. Ie washing machine, have a shower, boil the electric kettle, cook tea .....

Just a bit of an update and when I said I averaged 6kWh a day this was a simple calculation from my  electricity bills over a year. This method essentially masked how much of the electricity my PV panels produced and I used.

 

Now having had the battery a few months and taking daily readings of the PV meter and the grid meter I see I actually use on average 8.6kWh which is a surprise but for the fact we cook on electric. It does mean that we were probably only utilising about 2.6kWh on average throughout the year from the solar production, most being exported for 3p/kWh.

This is a little graphic I produced from my (almost daily) logging of grid use and solar PV production. The gaps show where I missed days and the following column is the total for the missed days and the current day. You will see some days the usage seems to drop down a lot, this is where the battery has stored from the previous day but the solar production has been low. These last several days also don't give a good picture because once the battery is full on a sunny day we have been exporting 2-6kWh/day. I would need another meter between the solar system and grid meter and before my consumer unit and this is not practical without a complete rewire as the consumer unit is shared by the solar/battery system. I intend to heat my water in the summer by solar electric and eliminate use of gas where possible.

 

So the battery has increased my utilisation of solar electricity greatly since mid February. Because of the weird logic of growatt ( the battery has an intermittent fault which requires a reset after it is full and the excess is exported, the fitting firm are being awkward) and that the battery was a retrofit imports from the grid will never be zero. I suspect I should have researched more and gone for another firm's inverter but heh...

 

The economics of the battery; it looks likely from March to October it will save us about 5kWh/day in electricity and some undetermined amount of gas many days in this period, so at current rates about  £1.20 plus savings in gas at 8p/kWh. Which will pay off in 10 years at worst, we'll see. I'll continue to monitor for a while but intend to just let the system get on with it.

 

What it flags up is the need to generate 2-6kWh/day in that deep winter period Nov-Mar and that is when the stove is running 16 hours a day. Pointing to the need for a simple themo-electric device.

 

Discuss.

 

 

[Dean0]

Long time lurker and my first post.

We've been fully  off grid for the last 6 months

Water pumped from well. Heating/ hot water from logs and power from 6kv of solar and 12kv of lithium batteries. All backed up with a 6kv diesel gennie.... Averaging out over the last 6 months, if solar produces 5 kv a day then gennie is not needed for normal use.... the solar side has

Been great but generator has been hassle reliability wise..... should have brought a new one.

 

Edited March 20, 2022 by Dean0
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