Off-grid, grid-tied, or hybrid?

[Trouble]

Hello Everyone,

We have recently purchased a 53' reefer trailer for conversion to a home/office. We want full off-grid capability, however we also want to net meter and have grid access for larger projects. I received a bid from Wholesale Solar for a 1.6 kW array and monthly output of 212 kWh. We are brand new to this, and I would love to hear back from any of you that are living off-grid as to the actual capacity of a system like this. Can two adults and a baby live somewhat normally with that kind of power?

If you are out there, ACTUALLY living off-grid, we want to know what it is that you are doing and how it is working for you. All suggestions welcome.

Thanks!

[Bala]

That works out to 7kwh a day. That is not much by todays lifestyle for most. Look at what your using in your current home. Off grid os a different way to live not just a different way to supply electricity.

[Mike90250]

We can skimp on stuff and get to 6KWh a day, but when we have 2 fridges & deep freeze, water pumping, 2 laptops and a TV, we are over 12KWh daily. If you can make a few adjusts to lifestyle, and a couple big energy efficient appliance purchases, I can see a household getting to 10KWh a day. Not much microwave or blowdryer usage allowed.

[Trouble]

That works out to 7kwh a day. That is not much by todays lifestyle for most. Look at what your using in your current home. Off grid os a different way to live not just a different way to supply electricity.

Thank you for the data. I have been thinking we should go a little bigger than that, but we also have fairly conservative energy use. Any insight as to whether a fully off-grid system is better than a hybrid one?

[Trouble]

We can skimp on stuff and get to 6KWh a day, but when we have 2 fridges & deep freeze, water pumping, 2 laptops and a TV, we are over 12KWh daily. If you can make a few adjusts to lifestyle, and a couple big energy efficient appliance purchases, I can see a household getting to 10KWh a day. Not much microwave or blowdryer usage allowed.

Do you use a washer or dryer? Water heater? When you say skimp, what kinds of things are you powering on 6 kWh a day? Sounds like you have plenty of gear and experience operating a system. Is your system fully off-grid, or hybrid?

[Mike90250]

we are fully off grid. If I feel I don't want to crawl out and start the generator in a nasty storm, we don't use much optional appliance power (washer, dryer, dishwasher). We have propane for water heating, cooking and clothes dryer. Everything is energy star and low power stuff. It's hard to do.

But for every watt you save, it's a watt you don't have to generate or store.

[inetdog]

If you want to both net meter and have power when the grid is down, then you have a couple of key requirements to meet:

1. You need a hybrid inverter system with the option of supplementing grid power and to sell power back to the grid when you want it to, but not otherwise. This is far more expensive than either a pure grid tie or a low cost off-grid-only installation.
2. You should use off-grid power (and put wear on your battery bank) ONLY when the grid is down. Otherwise for most (if not all) purposes you will be paying more for the power you make in off-grid or battery time shifted operation than you would for grid power at their highest possible rate.
3. Net metering (or even any grid tied connection without any sell back of overproduction) will require an interconnect agreement with your POCO and cannot be moved from one location to another without a separate interconnect agreement wherever you go. You may escape POCO's notice if you grid tie but never sell back, but do not count on it.
4. Since you will be living in the unit, the highest level of design and inspection (including permit) are called for. A travel trailer or RV may be able to avoid this level of inspection, but there is a risk involved.

[Trouble]

If you want to both net meter and have power when the grid is down, then you have a couple of key requirements to meet:

1. You need a hybrid inverter system with the option of supplementing grid power and to sell power back to the grid when you want it to, but not otherwise. This is far more expensive than either a pure grid tie or a low cost off-grid-only installation.
2. You should use off-grid power (and put wear on your battery bank) ONLY when the grid is down. Otherwise for most (if not all) purposes you will be paying more for the power you make in off-grid or battery time shifted operation than you would for grid power at their highest possible rate.
3. Net metering (or even any grid tied connection without any sell back of overproduction) will require an interconnect agreement with your POCO and cannot be moved from one location to another without a separate interconnect agreement wherever you go. You may escape POCO's notice if you grid tie but never sell back, but do not count on it.
4. Since you will be living in the unit, the highest level of design and inspection (including permit) are called for. A travel trailer or RV may be able to avoid this level of inspection, but there is a risk involved.

I am extremely glad to have joined this forum. You are all very insightful. We are getting in touch with the utility now, in order to find out if net metering is even available to us in an RV type situation. It is confusing, balancing budget with convenience with resiliency... I guess enough money will trump most problems, but what would you say is the best combination of self-reliance, system resilience, and affordability? Grid-tie? Off-grid? Hybrid seems a little new and maybe more expensive?

[Trouble]

we are fully off grid. If I feel I don't want to crawl out and start the generator in a nasty storm, we don't use much optional appliance power (washer, dryer, dishwasher). We have propane for water heating, cooking and clothes dryer. Everything is energy star and low power stuff. It's hard to do.

But for every watt you save, it's a watt you don't have to generate or store.

Thanks Mike! I am gathering that one would have to have a seriously massive system and bank in order to live a modern technological lifestyle. Are gas and propane necessary, in your experience, for off-grid living? I see the value in having a backup generator. Is there not a reliable way to heat water with solar? Ideally, we would like to build up a system that no longer required fuel inputs, but I'd like input on that from a veteran of off-grid living.

[inetdog]

The one general principle to keep firmly in mind is that using electricity to power resistive heating for water is a losing proposition.
Grid electricity to a resistive heater costs about as much as propane to the same size heater. And your cost per kWh in an off-grid system will be much greater than the POCO cost. Piped natural gas can be a lot less expensive, but is not an option for your RV.

If you have to use electricity to heat water, then you will get the best economy from a heat pump type system, but the initial cost will be high.

Have you looked at using solar thermal panels for water heating? They will compete for space with your solar PV panels.

[Mike90250]

Thanks Mike! I am gathering that one would have to have a seriously massive system and bank in order to live a modern technological lifestyle. Are gas and propane necessary, in your experience, for off-grid living? I see the value in having a backup generator. Is there not a reliable way to heat water with solar? Ideally, we would like to build up a system that no longer required fuel inputs, but I'd like input on that from a veteran of off-grid living.

Solar thermal water heating works great - when the sun shines. In winter, it's not reliable, and that's where the propane tankless heater goes to work.