Hi Rob and all, thanks for letting me join your forum. I've been spending many enjoyable hours reading and learning from the many interesting threads here.
I'm starting to plan / engineer a major solar upgrade (in stages), to an off grid cottage for a close friend. The cottage is co-owned by three people, I'm just a close friend who spends many wonderful hours on Lake Ontario and helping out with the technical stuff as no one else has any technical ability.
History / background:
The cottage is a two storey 3 bedroom (more like a home) on lake Ontario owner built in the 70's. It is mostly passive solar design, large south facing windows with large amount of interior stone mass, rarely goes below freezing in the winter. It has always been off grid as running in power would currently be in the $80K range and its mostly only used in the summer, although with the current mild winters it's used on some weekends. Driveway access in about 1.6km, difficult to walk in if you can't drive.
Heating is wood stove with propane for the stove/oven, hot water, fridge and BBQ. Electrical is 24vdc, two PV panels & battery bank. Lights are 24vdc LED's with a 24vdc servo motor running a double acting piston pump for water, both running directly off the batteries. The only 120vac supply is a 300 watt 12vdc inverter running off 1/2 the battery bank and is moved every so often to different cells to avoid unbalance, I know this is not ideal. The 120vac supplies the on demand hot water heater, cell phone charging and a radio. Everything currently works fine for the current cottage use.
Details of current equipment are shown at the end.
Why is an upgrade planned:
The batteries are getting to the end of their life and will have to be replaced in the next few years. Propane is a problem as delivery is not an option due to access. So we have 4 - 100lbs tanks, a manifold regulator system runs 3 tanks for the house and one for backup when we take the 3 tanks into town to be refilled. Problem is we are all over 65yrs and lugging the tanks into town for filling is not something we want to do in the future. Also the fridge is acting up and may need to be replaced soon, so would like to go electric 120vac off a new inverter. This would reduce the amount of propane used and also let us run a vacuum once in a while.
Options looking for input:
A) Staged to spread out the cost as 2 or 3 owners don't want to spend money
- Add 4 more PV panels, 24vdc 3500 watt inverter, & fridge 120vac
- Use the existing batteries till next upgrade, probably LiOn when the price is a little cheaper, 24vdc bank. Continue to run pump and lights directly off batteries.
- Use any excess power in the winter to run a dump load directly off the charge controller to a water tank with dc elements, keeping the battery room warm and maybe the cottage above freezing.
- I'm tending towards this option right now, but I have flip flopped several times.
B) Expensive all at once batteries and etc. etc.
- In this scenario my initial thought is a 48vdc bank would be the desired choice but many current LiOn banks BMS don't like 48 volts. Also this would require the pump and LED lights to all change, probably to 120vac.
- This determines the inverter choice 24 or 48 volts, don't want to change it again later.
Current System:
- PV array: 2 - Canadian Solar CS6P-260P currently wired parallel, want to change to series
Pmax 260 W, Vmp 30.4V, Imp 8.56A
Voc 37.5V, Isc 9.12A
- Charge Controller: Outback Power Flex 60
- Batteries: 12 - Gould 2V telephone backup approx 25 yrs old
I think they are FCT-25, 180AH and about 250lbs ea.
- Water heater: On demand propane direct vent Eccotemp i12 120vac
- Water pump: 24Vdc servo motor
- Lights: 24Vdc LED's
- Backup generator: Honda 2500W basic contractor
Staged Upgrade, my current thoughts, subject to change:
- Add 4 PV panels, two parallel strings of 3 in series, (2 new with 1 exist)
voltage wouldn't be a problem, but need to match the current so the existing panel does not drag down the string too much, not sure which one of your Hanwha or LG panels would be a good match. Otherwise adding another charge controller increases the cost.
- Add inverter, Outback Power VFXR3524
- Add OutBack Mate3 for programming, hopefully wouldn't need a hub, just swap between Flex60 controller and VFXR inverter, probably leave hooked to inverter most time.
- Add Fridge: 28 inch 14 cubic ft, Energyguide 336Kwh per year
The above should easily handle the current load but would like to run the inverter on search mode to reduce the 30 watts it normally draws on idle. On search I believe the fridge would have to be a mechanical thermostat as electronic circuits, relays & defrost cycles would get all messed up on intermittent power.
Sorry for the long first post, but as we are in lockdown again I have too much time to think and plan these things. Looking for brainstorming ideas from those of you who have been there done that. In the long term it can get expensive if you start down the wrong path and have to change course and equipment later.
thanks for any input you can provide
Gord
I'm starting to plan / engineer a major solar upgrade (in stages), to an off grid cottage for a close friend. The cottage is co-owned by three people, I'm just a close friend who spends many wonderful hours on Lake Ontario and helping out with the technical stuff as no one else has any technical ability.
History / background:
The cottage is a two storey 3 bedroom (more like a home) on lake Ontario owner built in the 70's. It is mostly passive solar design, large south facing windows with large amount of interior stone mass, rarely goes below freezing in the winter. It has always been off grid as running in power would currently be in the $80K range and its mostly only used in the summer, although with the current mild winters it's used on some weekends. Driveway access in about 1.6km, difficult to walk in if you can't drive.
Heating is wood stove with propane for the stove/oven, hot water, fridge and BBQ. Electrical is 24vdc, two PV panels & battery bank. Lights are 24vdc LED's with a 24vdc servo motor running a double acting piston pump for water, both running directly off the batteries. The only 120vac supply is a 300 watt 12vdc inverter running off 1/2 the battery bank and is moved every so often to different cells to avoid unbalance, I know this is not ideal. The 120vac supplies the on demand hot water heater, cell phone charging and a radio. Everything currently works fine for the current cottage use.
Details of current equipment are shown at the end.
Why is an upgrade planned:
The batteries are getting to the end of their life and will have to be replaced in the next few years. Propane is a problem as delivery is not an option due to access. So we have 4 - 100lbs tanks, a manifold regulator system runs 3 tanks for the house and one for backup when we take the 3 tanks into town to be refilled. Problem is we are all over 65yrs and lugging the tanks into town for filling is not something we want to do in the future. Also the fridge is acting up and may need to be replaced soon, so would like to go electric 120vac off a new inverter. This would reduce the amount of propane used and also let us run a vacuum once in a while.
Options looking for input:
A) Staged to spread out the cost as 2 or 3 owners don't want to spend money
- Add 4 more PV panels, 24vdc 3500 watt inverter, & fridge 120vac
- Use the existing batteries till next upgrade, probably LiOn when the price is a little cheaper, 24vdc bank. Continue to run pump and lights directly off batteries.
- Use any excess power in the winter to run a dump load directly off the charge controller to a water tank with dc elements, keeping the battery room warm and maybe the cottage above freezing.
- I'm tending towards this option right now, but I have flip flopped several times.
B) Expensive all at once batteries and etc. etc.
- In this scenario my initial thought is a 48vdc bank would be the desired choice but many current LiOn banks BMS don't like 48 volts. Also this would require the pump and LED lights to all change, probably to 120vac.
- This determines the inverter choice 24 or 48 volts, don't want to change it again later.
Current System:
- PV array: 2 - Canadian Solar CS6P-260P currently wired parallel, want to change to series
Pmax 260 W, Vmp 30.4V, Imp 8.56A
Voc 37.5V, Isc 9.12A
- Charge Controller: Outback Power Flex 60
- Batteries: 12 - Gould 2V telephone backup approx 25 yrs old
I think they are FCT-25, 180AH and about 250lbs ea.
- Water heater: On demand propane direct vent Eccotemp i12 120vac
- Water pump: 24Vdc servo motor
- Lights: 24Vdc LED's
- Backup generator: Honda 2500W basic contractor
Staged Upgrade, my current thoughts, subject to change:
- Add 4 PV panels, two parallel strings of 3 in series, (2 new with 1 exist)
voltage wouldn't be a problem, but need to match the current so the existing panel does not drag down the string too much, not sure which one of your Hanwha or LG panels would be a good match. Otherwise adding another charge controller increases the cost.
- Add inverter, Outback Power VFXR3524
- Add OutBack Mate3 for programming, hopefully wouldn't need a hub, just swap between Flex60 controller and VFXR inverter, probably leave hooked to inverter most time.
- Add Fridge: 28 inch 14 cubic ft, Energyguide 336Kwh per year
The above should easily handle the current load but would like to run the inverter on search mode to reduce the 30 watts it normally draws on idle. On search I believe the fridge would have to be a mechanical thermostat as electronic circuits, relays & defrost cycles would get all messed up on intermittent power.
Sorry for the long first post, but as we are in lockdown again I have too much time to think and plan these things. Looking for brainstorming ideas from those of you who have been there done that. In the long term it can get expensive if you start down the wrong path and have to change course and equipment later.
thanks for any input you can provide
Gord
