Last year I published a post called Why Not the Sun? where I argue that everyone should switch to solar power to cover the world’s massive - and growing - energy needs. In the post, I write that we’re considering putting solar panels on our house. This summer, we actually went ahead and did it. We now have a 7kW solar power plant on our roof.

The plant has been operational for about a month now. It was offline for a few days because of an inverter malfunction, but for the rest of the month the solar panels have worked like a charm. Here’s a graph showing how much power we pull off the public grid in a typical week since the plant came online:

It’s beautiful, isn’t it?

Excess Electricity

On a sunny day, all the electricity we use between 7 and 15 is generated by the solar panels. During those hours, we actually produce a lot more juice than we’re using, which means there’s plenty of excess electricity.

Ideally, it would have been stored in batteries. Unfortunately, batteries are still quite expensive. I’m not sure I want to have what is, for all intents and purposes, a bomb, stored in our basement, either. So instead, the excess electricity is pushed to the public grid, where it’s sold. We make a little money, and the clean solar power can - at least in theory - replace coal power somewhere else.

This autumn, our electricity company will start a service they call a “solar account”. It works in the same way as a bank account, except you don’t put money on the account, but electricity. All the excess power that is generated during the day is deposited into the solar account. When the sun goes down, the solar panels are no longer able to produce enough energy to cover our electricity need. Instead, electricity can now be withdrawn from the account and used. In practice, this works as a virtual battery.

The electricity withdrawn from the account is not the actual solar power we deposited, of course. The real benefit you get from a solar account is that you don’t have to purchase electricity when it’s in high demand, and thus at its most expensive. The demand is usually higher in the morning and in the evening - when the solar panels don’t work all that well.

Solar Power Caveats

Unsurprisingly, the main challenge with solar panels is that they are relying on the sun. No sun, no power. A solar power plant is also a surprisingly complicated thing to install. In addition to the solar panels, you’ll need a solar inverter to actually use the electricity generated. And, to make sure you don’t fry yourself or fall off the roof, everything has to be assembled by qualified professionals¹.

Solar panels are installed in such a way that the panels in the plant will only be as efficient as the least potent solar panel. If there is something that throws a shadow on one of the panels, the efficiency of the entire solar plant goes down. This is usually not a problem for most commercial and rural power plants. They are typically located in large, open areas. But for urban and suburban plants it might be an issue. In our case, we have a surprisingly wide array of chimneys and air ducts on the roof. They cast ominous shadows on the solar panels, which means we’ve had to install power optimizers to negate the shadow issue. The optimizers solve the problem, but at an additional cost.

Ka-ching, ka-ching!

While we’re on the subject of cost, putting solar panels on your roof is pricey as fuck. The power plant cost us roughly $17,000 in total to install. With today’s electricity price, the power plant won’t be paid off and generate actual revenue until 2039! But a lot of things can happen to the electricity price - and the world - before 2039. The electricity price is likely to increase, meaning the plant will be paid off quicker. And the world is likely to go down the drain, meaning that having our own solar power plant is an absolutely brilliant thing.

While the initial investment is considerable, there’s very little additional cost later. The power plant requires virtually no maintenance. There are no moving parts, and the panels are cleaned whenever it rains. The solar panels have a guaranteed lifetime of 25 years, and might last much longer than that. The solar inverter probably has to be replaced in about 15 years, but that’s all there is in terms of maintenance costs.

It’s also worth mentioning that we’ll get about $2000 from Enova. The government agency reimburses a percentage of the cost when companies and private individuals make investments that reduce greenhouse gas emissions. Even though it’s me paying myself with my own tax money, it’s a good effort by the government.

Final Thoughts

The solar panels will not cover all our electricity needs. In theory, the power plant is large enough to do that, but the sun isn’t there 24/7. The solar panels will generate between 6,000 and 7,500 kWh of actual useful power. That’s more than half of our annual consumption. So far in August, we’ve pulled about 250 kWh less from the public power grid than we did in August 2018. It will be interesting to see how the grid consumption gets when we heat the house during the winter months.

As a financial investment, installing solar panels is surely insane, at least with today’s installation cost and electricity prices. But as an investment in sustainability, it’s a no-brainer. The more people install solar panels, the quicker the prices will drop. The industry’s intensive to pour more money into solar technology research will also increase.

If you live in Norway, and the idea of installing solar panels on your roof tickles your fancy, check out Solkart.no. The site will give a rough estimate on how much power you can generate, and how much the solar power plant will cost. If you decide to go ahead, I’ve got a reference link that will give you NOK 2000 off the cost if you chose to use the same contractor I did.