I am new to all this and looking for feedback on my 'off grid' system
Posted: Sun Oct 09, 2022 3:10 pm
Hello everyone,
I'm new to the idea of running my home from solar power, I've been lurking on these forums for a while and I've already learnt a lot, so thanks to everyone who posts so much great information and thanks for letting me join.
I've been thinking about going solar recently, and I've come up with a design for an "semi off grid" system that I think would work for my situation.
I've got a small house (2 bedrooms) and we use about 5kWh of electricity a day. Heating is from a combi boiler so about 50% of my energy spend goes on gas, and I think the only realistic thing I can do to reduce that is buy a newer more efficient boiler.
My idea is based around the Victron EasySolar II. Basically the plan is:
- 2400W of PV panels on the roof - that's all that will fit.
- EasySolar II as the hub of the system
- 5kWh of batteries charged from PV. Haven't decided yet whether to go for AGM or Lithium batteries.
- Fit a new consumer unit alongside the existing one, and move most of the house circuits to the new unit.
- Power the new CU from the inverter.
- Leave the 2.5kW electric oven and smoke alarm circuits on the mains powered CU.
- Add another output to the existing CU with a timer switch that connects mains to the Victron overnight, to charge batteries on Economy 7.
I get the impression that feeding power back to the grid is not really worth it, especially with only 2.4kW of panels, so I'm not bothered about that. The EasySolar can apparently be programmed to disable grid feed, and it would only be connected to the grid at night anyway.
Basically the entire house, except the oven and the smoke alarms would be supplied from the inverter. I would probably plug my freezer into the 13A socket on the oven switch, at least in the short term, until I know that the batteries won't die during the day.
Obviously the most important question I have to ask is - is this a sensible idea?
More specific questions I need to consider:
24V or 48V batteries? I think that the 3kVA inverter will be enough, but there is a 5kVA version that only accepts 48V.
Is is feasible to expand the system in the future by adding more batteries and a second stand alone inverter? Probably with yet another CU, and distribute the house circuits between CUs as appropriate. Actually on reflection it's probably a better idea to buy the 5kVA inverter in the first place.
Most important detail I don't really understand - how to earth the new system? Can the inverter fed circuits share an earth with the mains? I see the EasySolar includes an earth relay but I don't really understand the use of this.
Many thanks for any advice you can offer!
Edit - It occurs to me that this is more of a "battery storage system with a bit of solar" - a fair amount of my power will be coming from Economy 7 rather than the solar panels. So apologies if I've posted in the wrong section.
I'm new to the idea of running my home from solar power, I've been lurking on these forums for a while and I've already learnt a lot, so thanks to everyone who posts so much great information and thanks for letting me join.
I've been thinking about going solar recently, and I've come up with a design for an "semi off grid" system that I think would work for my situation.
I've got a small house (2 bedrooms) and we use about 5kWh of electricity a day. Heating is from a combi boiler so about 50% of my energy spend goes on gas, and I think the only realistic thing I can do to reduce that is buy a newer more efficient boiler.
My idea is based around the Victron EasySolar II. Basically the plan is:
- 2400W of PV panels on the roof - that's all that will fit.
- EasySolar II as the hub of the system
- 5kWh of batteries charged from PV. Haven't decided yet whether to go for AGM or Lithium batteries.
- Fit a new consumer unit alongside the existing one, and move most of the house circuits to the new unit.
- Power the new CU from the inverter.
- Leave the 2.5kW electric oven and smoke alarm circuits on the mains powered CU.
- Add another output to the existing CU with a timer switch that connects mains to the Victron overnight, to charge batteries on Economy 7.
I get the impression that feeding power back to the grid is not really worth it, especially with only 2.4kW of panels, so I'm not bothered about that. The EasySolar can apparently be programmed to disable grid feed, and it would only be connected to the grid at night anyway.
Basically the entire house, except the oven and the smoke alarms would be supplied from the inverter. I would probably plug my freezer into the 13A socket on the oven switch, at least in the short term, until I know that the batteries won't die during the day.
Obviously the most important question I have to ask is - is this a sensible idea?
More specific questions I need to consider:
24V or 48V batteries? I think that the 3kVA inverter will be enough, but there is a 5kVA version that only accepts 48V.
Is is feasible to expand the system in the future by adding more batteries and a second stand alone inverter? Probably with yet another CU, and distribute the house circuits between CUs as appropriate. Actually on reflection it's probably a better idea to buy the 5kVA inverter in the first place.
Most important detail I don't really understand - how to earth the new system? Can the inverter fed circuits share an earth with the mains? I see the EasySolar includes an earth relay but I don't really understand the use of this.
Many thanks for any advice you can offer!
Edit - It occurs to me that this is more of a "battery storage system with a bit of solar" - a fair amount of my power will be coming from Economy 7 rather than the solar panels. So apologies if I've posted in the wrong section.