# Is my calculation correct?

If the installed capacity of a Solar system is rated at 1MWp and the location where this system is installed gets about 3000 hours of Sun in a Year then the system is capable of generating 3000 Mega-Watt-Hours/Year of Electricity.

If this system is connected to a Grid and the Rate the Utility company pays for supplying electricity is \$0.10 per KwH then you get paid

3000*1000*\$0.20=\$300,000/Year.

Did I get this right?

When I read in the media that a 250MWp solar plant is installed and the location gets 3000 Hours of Sun, is it then saying that the system produces

250MW*3000Hours = 750,000 Mega-Watt-Hours

or

If the system is only 25% efficient then the actual output from the plant per year is only

250MW**25%*3000Hours = 187,500 Mega-Watt-Hours

Thanks for the clarification.

Re: Is my calculation correct?

Not quite sure where you are heading with your questions... Some numbers:

A "standard" power plant costs around \$1/watt to build (solar probably more).

The Solar PV Plant in Arizona (one of the biggest in the world) breaks even around \$0.09 per kWhr (excluding transmission line costs).

From my PG&E bill--roughly 50% of my home bill is to pay for the generation of electricity, the other 50% pays for Distribution and Transmission costs (local distribution, by far, the largest portion vs transmission costs). My power averages roughly \$0.12 per kWhr, but my rate plan runs from \$0.09 to \$0.50 per kWhr (rate tiers, peak/off peak, summer/winter). If you use a lot of power (say AC), you can get upwards of \$0.35 per kWhr real easy (on flat rate residential tiered rate plan).

The rated output of a solar (or any power plant) should be the MWatt output--should be no deratings (those are on the input power/heat/fuel/conversion losses--best power plants are around 50% efficient--give or take).

A solar power plant will probably average around 4-5 hours of "full" sun per day through the year (yes the sun is up 12+ hours, but equivalent power is 5 or so hours of noon day strength sun of 1kW per sq. meter). (my favorite link for the solar data is down this weekend--so these are SWAGs).

So, call it 4.5 hours of sun over the year * 365 days = 1,642 "hours of full sun per year"

I would guess a 250 MW plant would generate (caution, these are real rough numbers):

250 MW * 1,642 hours of full sun = 410,500 MW*Hours per year

A 1MW peak solar plant may generate around 1,642 MWatt*hours or 1,642,000 kWhrs per year. At \$0.10 per kWhr, that would be \$164,200 per year (again, real rough numbers).

The above is probably close enough for a first approximation of power output and costs...

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Re: Is my calculation correct?

I’m planning to setup a PV module assembling plant. I’m looking for help in preparing the business plan. Anybody could help me in this.
Best Regards
• Solar Expert Posts: 639 ✭✭✭✭
Re: Is my calculation correct?

Along those same lines, over the last 5 or so years of numbers in Green Bay, WI. I have found the wattage of the array is just below what its output in KW/hrs per year.

For example my old 480w array typically produced about 500 kw/hrs a year (ranged from 500 to 530). So to keep it simple I assume about the same as the panels per year. It will be interesting to see if my new location and setup match this or not.

Sorry I have no idea about setting up a business plan. I thought I remember from collage if it didn't pay for itself in 5 years it wasn't worth investing in.
3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: Is my calculation correct?

if you are planning to make the solar cells then be prepared for some very large expenses for the equipment to make these. it also has to be very clean like an operating room with the employees wearing masks, gowns, etc. the glass is specialized in being very low in metalic content and good sealers are also used after the cells had been properly placed and soldered. the finally is the aluminum frame. oh and the biggy is getting approvals for its electrical performance like ul, but there are many out there if other countries are giving their approvals too.
this is a very rough overview and i'm understating it, especially the expenses of it.
• Solar Expert Posts: 9,583 ✭✭✭✭✭
Re: Is my calculation correct?
niel wrote: »
if you are planning to make the solar cells then be prepared for some very large expenses for the equipment to make these. it also has to be very clean like an operating room with the employees wearing masks, gowns, etc. the glass is specialized in being very low in metalic content and good sealers are also used after the cells had been properly placed and soldered. the finally is the aluminum frame. oh and the biggy is getting approvals for its electrical performance like ul, but there are many out there if other countries are giving their approvals too.
this is a very rough overview and i'm understating it, especially the expenses of it.

PLUS, consider the warranty aspect - Can YOU guarantee (and post the bonds) to cover your construction, and the failure of the actual solar cells you are putting together ? That's why the cell manufacturer usually builds and warrantees the panels.
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