PV Gap

Lawrence Said:

How much energy do 5KW solar panels roughly create in KWH/Day?

We Answered:

It depends on where you are, how many sun hours are available. Sun hours are the number of hours that equals the standard test condition that panels are rated at. This number changes throughout the year with the seasons, but you can find an annual average and use that number. A nice average is 5 hours. 5kW x 5 sun hours = 25kwh (kilowatt hours). Generally, there's about a 30% loss in a grid-tied system, between wire losses, inefficiencies, less than ideal sun, dirt on the panels, etc. so you can realistically expect 17.5kwh a day, 525kwh a month, or 6300kwh a year. Depending on where you are.

Adrian Said:

Solar energy?

We Answered:

Wow. I can't possibly figure that out but if it's a lot let me know

Tonya Said:

If the amount of solar energy striking the ground in San Antonio averages 4.9 kWh/m2/day....?

We Answered:

4.9 kWh/m²/day x 1 m² = 4.9 kW-hr/day

multipy by 0.15 to get 0.735 kW-hr per day or 735 watt-hrs per day.

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Leah Said:

I am interested in Solar Energy.. I need HELP kw? kwh?

We Answered:

The first point is about the 10KW figure mentioned. If your system is rated below 10KW capacity you fit into the category of microFIT system which can pay that 80c/kWh.

On ratings..
The size of your system is rated in kW, meaning the power it can produce under standard sun conditions. Think of this as the capacity, like the hp of your car engine. It may be 1.5Kw for example. That is under 10kW, so works for microFIT. It relates to the size and number of your panels.

The figure you are paid on is in energy units, kWh (see document below). This is the product of kW fed into the grid and hours, so is the same energy as electrical units you buy from the electricity supplier at a much lower cost. Excess energy during the day is feeding in to the grid rather than being drawn out. How much is that? Well I don't know the equivalent of full sun daylight for Ontario, but lets say it is 3h per day. This means that during the daylight hours say 8h there is the equivalent of 3h of full sun shining on the panels. It varies for summer and winter.

Then your 1.5kW of panels would produce approaching 1.5kW x 3h = 4.5kWh per day (when the sun is there). This is the total production. How much of this is fed in? It depends on the amount you use in the house when the sun is shining (the 8h period in the example). It may be you use more than 4.5kWh and end up a net buyer of power, or say only 2.kWh as no-one is home and there is only one fridge using say 500W for 4 hours of the sunlit part of the day. This would mean your excess production is something like 2.5kWh per day - say 2.0kWh after allowing for losses in the inverter, wiring, dirty panels.

I think that low amount of usage will not be very likely. There is always other stuff on all over the house. It depends on your pattern of use, weather, weekends, etc. Of course while there is no sun the power is only what you buy from the grid. Get an understanding of your usage using the electric supply meter. Just read the total kWh used during the hours of daylight, by taking two readings at say 8am and 4pm, subtracting the start reading..

Expolaining again...
The feed in power is the net surplus at each instant of the time. This is similar to the energy produced in the daylight hours minus the energy used in those same hours. This example produces 4.5kWh in a particular 8h. The usage might be as low as 2kWh in that same period, if you are very careful. The excess is 2.5kWh, but allowing only 80% of that after losses it is 2kWh.

Generally speaking the 1.5kW capacity system is too small to sell much power back. Most people need more like a 5kW system - the closer to just under 10kW the better. You will need to take care with power usage patterns. Consult with others who have a similar setup and experience in your region. Don't be over optimistic. For comparison a 10kW system may be producing an excess from 0 (buying) to ~26kWh per day, but I expect the higher figure is optimistic.

Continuing with the car analogy, the feed in production in kWh is more like getting paid for the number of miles your car travels in a day or a year, but only for the work related part, or with some other conditions imposed..

Be careful to understand all the conditions like "domestic content". Talk to others who have done this to make sure you understand. It seems the conditions have changed in the last month or two.. I have to say that it would not be written in stone for this generous subsidy to continue for long. New government might change it. There is a 20 year contract, so it needs to be fully understood what your commitment is.