Posting to answer a few questions, and share the data I've found on other postings here so far...

A gas system would be delightful, but not possible in my location.
I do not have solar heating.

Actual usage data I've discovered so far from other posts:

Elektra Semiautomatica
1 hour consumed 0.30 kWh
2 hours consumed 0.45 kWh
3 hours consumed 0.60 kWh

Silvia, uninsulated
60 minutes - 0.12 KWH
120 minutes - 0.17 KWH
180 minutes - 0.23 KWH

Anita
1.89 kWh over 17.6 hours

GS/3
3.53 kWh / 12 hours
4.48kWh / 24 hrs

Would anyone else like to help me with some usage data? What I'm trying to get at is whether I can afford (kWh not purchase price) a quality espresso machine at my location. Solar is 'free'; beyond that generator power is about $1/ kWh.

If the PV system is properly designed, then you can "afford" the kWh for 6+ months out of the year. In the winter, you'll probably be on an energy budget regardless of whether you have an espresso machine or not. In between the flush season and the lean season, your energy budget will depend on weather patterns.

As I once heard an off-grid veteran (and owner of a PV installation company) say, "Some days are waffle days; some days are pancake days." In other words, if you can't afford the kWhs to make espresso (waffles), then you adjust by making brewed coffee (pancakes) and heat the water on the stove. You shift the load off of the batteries and over to propane or wood. This is pretty typical adjustment in an off-grid scenario in the winter.

As a reality check, you can expect to generate about ±2 kWh per 1 kW of PV capacity per day in Idaho in the winter in an off-grid situation. In the summer you'll have the potential to generate closer to ±4 kWh per kW per day. However, once the batteries are full, the array just sits there and essentially does little or nothing. Float charging the batteries uses very little current, which is the bitter irony of off-grid PV: You'll be float charging the batteries and doing very little real work exactly when you have the greatest solar potential. So in the summer, you want to have daytime loads. Use it or lose it.

The seasonal daily averages above are back of the napkin estimate, but I'm using a tool from NREL that has a 30-year average weather database and I'm strategically adapting the inputs to simulate an off-grid scenario:

http://rredc.nrel.gov/solar/calculators ... Boise.html

To give you another point of comparison, you can have a look at Chas Rimpo's power analysis with the La Spaziale S1 Vivaldi: http://s1cafe.com/s1v1/S1Power.php

This is a commercial double boiler machine, but you can have a look at the coffee / steam boilers indepently.

I think you need to look at two aspects:
- peak power, when all heating elements, pump, solenoid are on. This is easy to calculate, with most specs sheets. This identify the max inverter power you need for the espresso machine.
- average power usage (kW-h/day) to see how this will tax your battery bank.

Do you have access to a gas stove?

In addition to the portapresso, how about the mypressi twist or the hand-presso ? If no gas stove, an electric kettle could get you there with two of those three; I have a kill-o-watt, and know someone with a bonavita electric kettle, so I'll grab some data for you on it this weekend if you like.

Electric kettle is easy to measure since it heats at 100% until done. It is probably the most energy efficient (electric) method to heat water, versus a big boiler. Building up pressure takes lots of energy dumped into the water, and you heat far more than you are going to use.

Do you steam milk, or just pull shots? You can optimize if you aren't interested in steaming by using a DB with the steaming switched off, or an SBDU. Or use a caravel or twist with water boiled on the stove or in an electric kettle.

jedovaty wrote:I have a kill-o-watt, and know someone with a bonavita electric kettle, so I'll grab some data for you on it this weekend if you like.

Yes, please. This would be helpful.

Electric kettle is easy. They max out at ±1,400 watts. That's basically the biggest load you can put on a 15 A receptacle because the National Electrical Code requires a 125% safety factor (1,400 W ÷ 120 V = 11.7 A x 125% = 14.6 A). If it takes 5 minutes (0.083 hours) to boil 1.5 liters of water, then you have used 0.117 kWh (1,400 W x 0.083 hours).

If you just need to boil water, the precise power rating of the kettle doesn't matter much. Here's why. You'll need to do the same amount of work to bring the volume of water to boil regardless of whether your kettle is 1,000 W-rated or 1,400 W-rated. With more power you'll just be able to boil the water more quickly.

If you want to do off-grid espresso, a My Pressi or similar solution would be great. You don't have to bring a massive machine to temp, just the water-and you won't need much water. That's super efficient. You can use propane or wood if need be.

The next best thing is to use a small single boiler or HX machine or similar that you can turn on and off quickly if need be. These machines use the rated power, like 1,000 or 1,200 watts, whenever the boiler coil cycles on as determined by the P-stat. Over 15 or 30 minutes, the coil is probably only on 50% to 75% of the time. This is where an insulated boiler is good, because the insulation reduces the frequency of the on/off cycling.

What you'll want to avoid are commercial machines that require 240 Vac and weigh a whole lot, as all of that mass needs to come up to temp in order to pull a shot. Look for a small components that only need 120 Vac.

I made two pour over coffees every morning for 6 weeks last fall using an electric kettle in an off-grid cabin in Southern Oregon. If the PV system is properly designed, it will support these types of loads. No problem. (If the system can't run your electric kettle, then it won't run power tools or pump water, and you'll have bigger problems than coffee.) In the winter, the worst case scenario is you need to burn stuff-but chances are you'll need to do that for heat anyway.



(The biggest portion of the ±2kW PV array is actually top-of-pole mounted to the east of this power shed, which houses the batteries, inverter, etc, and doubles as a workshop-with a view of Mount Ashland.)

Just for fun, I dusted off my KILL A WATT meter and used it to measure the kWh required to make an 8 oz cappuccino for my wife and 12 oz pourover for me. These tests were done back to back so the ambient conditions were the same.

Espresso machine: I'm using a 1,100 watt Pasquini Livietta (a rebranded Olympia Maximatic) at home. While the Olympia machines manufactured post-1983 have uninsulated boilers, I have added boiler insulation to my machine. I filled the boiler on the espresso machine to the top of the sight glass indicator prior to the test. I let the machine warm up for 15 minutes prior to pulling the shot. Including the milk steaming and clean up routine, the total run time was ±18 minutes. The energy consumption was 0.16 kWh.

Electric kettle: I am using a 1.5 liter, 1,400 watt Oster kettle for brewed coffees. I filled the Oster kettle to the 1.2 liter mark, which is my normal routine for a single brewed coffee. While this is more water than is absolutely necessary, I'm a compulsive filter rinser and want extra water in the Hario kettle for thermal mass to provide temperature stability while brewing. I poured off 14 oz of rinse water at about 4 minutes, then stopped the kettle just shy of boiling at roughly the 5 minute mark. The energy consumption was 0.10 kWh.

(FWIW: the power demand of an espresso machine will tell you very little about the energy it will use to make an espresso drink. Instead, look at the boiler volume and the weight of the machine. Machines with more boiler volume will take more time to come to temp. Similarly, a more massive machine will wick more heat away from the boiler as it tries to come to temperature. Boiler insulation is good because it keeps the heat where you want it and reduces on/off cycling frequency.)

My CC1 (~1100W, .5l insulated boiler, pid) uses < .5kwh per 16 hours on, making about 6 doubles without steaming).

This is over the last month. It's plugged into a Seasonic kill-a-watt type device and never unplugged.

I do power the machine off for 8 hrs. a night.

The PID has adjustable settings that vary the time to temp, and max Watt usage / pulse interval.

In other words, the heater is almost never fully on but pulsing. When the pump is on, it uses about 80W. 99% between brewing it's at 1W probably sampling the temp.

But coming up to heat the first time on, it will peg ~1140W up to the last few degrees of target. After a flush or down to ~190 deg @ grouphead, it will start using about 450W decreasing as it approaches target temp to avoid overshoot.

(for those who dig into the CC1 pid settings, this is P6=3, my factory default when I got it was P6=0, even less power usage, and overshoot - basically none, but slower initial warm up, and back to back readiness).

Wow. Probably not a counter-top espresso machine out there with a smaller energy footprint. Low boiler volume w/ intelligent controls. That's the ticket.