Thanks for the tip. I'm actually working on a video series right now that looks at these sorts of numbers in-depth. Here's what I found for solar panels and accumulators.

The day/night cycle is 416.67 seconds long. It is broken up into 4 periods: 50% daylight, 20% dusk, 10% night, and 20% dawn. During dawn the light drops linearly from 100% to 0% at night, and it comes back linearly during dusk. We can easily calculate the area under the curve (integrate) to come up with the average light production during the day. The area under a linear rise or fall (a triangle) is 1/2 of its maximum height, so that gives us:

(day)   0.5 * 1.0 = 0.5
(dusk)  0.2 * 0.5 = 0.1
(night) 0.1 * 0.0 = 0.0
(dawn)  0.2 * 0.5 = 0.1
-----------------------
Average:            0.7

We also know that a solar panel produces 60kW of power and that an accumulator can store up to 5MJ of energy. Notice that we are mixing energy and power (energy over time). To account for that, we'll have to consider the amount of time. If we want our accumulators to provide the same amount of power during the night as our solar panels were providing during the day, we'll need to determine how much energy they need to hold, so we'll need to determine how much energy the solar panels would have produced.

Remember from above how the power falls off linearly in the dusk, is out entirely in the night, and rises linearly throughout the dawn. The total amount of energy missing is just the opposite of the power production, so 30% of our energy production is missing and needs to be made up for. Since the day/night cycle is 416.67 seconds long, that means we need to 0.3 * 416.67 = 291.67 seconds of our energy production. Keep in mind that power means energy over time, so 1MW is the same as 1MJ of energy per second. This means, to provide an average of 100MW of power throughout the night, we will require 291.67 seconds * 1MJ/second = 291.67MJ of energy storage. Now we can work out the ratios of solar panels and accumulators.

1 panel * 0.060MJ/s * 291.67 seconds * 1 accumulator/5MJ = 3.5 accumulators per panel.