Alco Dekker 5,0 11 Apr 2026 Google

First of all, we have a challenging roof: steep, flat roof tiles, east/west facing, with shady areas (not flat/south-facing). We extensively compared quotes from about 10 installers regarding panels (Chinese or German?), inverters, terms and conditions, including installation warranties and reviews, and had several inspections. Koller wasn't the cheapest, but competitively priced in terms of specifications (DMEGC 405WP panels, Enphase), and it's convenient to use a reputable local company in case of problems. - What immediately stood out compared to all the other companies: Koller's inspection before submitting a quote was very comprehensive. The entire roof was measured. Tim indicated that he will always have a team come out for challenging roofs. - A good installation plan is especially important for us. Many installation plans were similar, but some companies predicted rather high yields or forgot trees. Koller's plans were realistic and clear (where does a panel yield more/less?). Luuk and Tim patiently brainstormed with us and discussed a total of 8 (!) options. Their recommendation was to leave a specific section of roof unpainted, but to continue with our garden shed (using a dummy conduit because the garden was open anyway)! It turns out that the forecast for each panel was quite accurate, and the installation yielded more than anticipated. - The installation itself went smoothly and faster than expected, neatly concealed in the meter box. Installers consulted with us as needed. The only downside was damage to a PVC pipe near our pond caused by a slipped roof tile. This was repaired properly the next day – thankfully, Koller handles all kinds of installation work. Ultimately, we received the latest Enphase IQ8plus inverters, which are prepared for a potential battery, even better than the quote suggested. Many thanks for the thorough, no-nonsense approach to Tim, Luuk, and Walter + team! And for that, a genuine 5-star rating!

Henk Klock 5,0 11 Apr 2026 Google

On the last workday of the year, I finally found a time to fix a running toilet. Kudos to the operator, who was friendly and worked hard to find a solution. The technician, despite the busy day, was also friendly and resolved the problem efficiently.

thijmen lieverst 5,0 11 Apr 2026 Google

I would like to express my sincere appreciation for the excellent work you did installing my Intergas boiler. The craftsmanship and professional approach are truly impressive. What was particularly striking was the clear communication prior to installation, which made the entire process even more enjoyable. Your dedication to quality and personal attention made this experience extra special. Thank you not only for the flawless installation, but also for your friendly approach.

herman ten klooster 5,0 11 Apr 2026 Google

Last week, Koller installed 15 solar panels for us in Hattem. We've had plenty of sunshine this week, so we've already generated a nice amount of power, which we can use to charge our car, among other things. And to top it all off, we received a delicious congratulatory cake this morning with a picture of our house on it. Wonderful! A thoughtful gesture and excellent, personalized service throughout the process. Thanks, Koller!