Power consumption by electric pumpjack

Re: Power consumption by electric pumpjack

Sorry--fixed the above equation--Had too many distractions when I typed up the post and I mixed 1,000 watts and 1 KW in the same equation.

The actual number is 320,000 watts of Grid Tied solar panels to drive a 50 HP motor 24x7 in Austin Texas--assuming 1 year net metering plan.

-Bill

Re: Power consumption by electric pumpjack

I picked 1,000 watts per HP as just a round number to estimate for losses---As you say, the exact measurements will give you a more accurate number to start with.

A couple things--You might check with the local electric utility--perhaps a joint project (centralized array, perhaps even on power company property, etc.). A little green marketing by both companies.

Also, at those power levels, you may look at Time of Use billing and how that will affect your array sizing...

For example, my rate plan has $0.30+ per kWhr for summer rates between noon and 6 pm and we have $0.09 for off peak rates the rest of the year (peak winter rates are $0.12 per kWhr--but is it more complex, because we have tiered ratings--the more power I use, the higher rates I pay).

We get almost 3x the money for noon-6pm summer generation and use that extra money to purchase off-peak power... Makes our array look "larger" by 3x for summer peak generation (we turn off most of our power during peak summer rates).

Depending on your spread sheet (cost of power, cost of solar, can you shut down a well pump during high power costs, what the power company could do to work with you guys, etc.)--it can be a very interesting engineering/MBA cost benefit study.

-Bill

Re: Power consumption by electric pumpjack

You can use your MBA skills to do the present value / future worth calculations... But you can make some starting assumptions. Assume a system costs around $7,000 per 1,000 watts of solar array for a Grid Tied system.

In Austin TX, a 1,000 watt array will generate around 1,362 kWHrs per year. Assume no costs over twenty years:

• $7,000 per 1kW of panels / (1,362 kWH per year * 20 years per 1kW of panels) = $0.26 per kWH over 20 years

Subtract 30% federal energy tax credit (if available for large commercial systems). Add property taxes for system over 20 years. Subtract depreciation over XX years. Add maintenance (new inverters every 15 years?). Add cost of funds over 20 years, etc...

But, as you can see--the costs currently may not make a lot of sense for you if it costs $0.26 per kWhr to run your system vs $0.10 per kWhr in charges from the utility.

In California, we have "Reservation Charges" which means, roughly, that 1/2 of a commercial power bill is for the infrastructure (wires, poles, transformers, etc.) and the other have is the cost of power generation (generators, fuel, etc.).

A school district found that reservation charges went higher (peak solar output 15 minute period per 1 year is higher than the peak power consumed by the school) and the money offset for generation costs was much less than they counted on in their economic model.

In any case, to properly figure out the cost/benefit ratio of solar GT vs Utility Power on a large system--there are many factors that need to be taken into account--including the politics of power (both state and corporate)--that make this a pretty sophisticated project to cost out.

-Bill